In vitro and in vivo association of an oviduct estrus-associated protein with bovine zona pellucida

Sperm and oocyte as carriers for bovine viral diarrhoea virus biotypes during in vitro fertilization

Bovine viral diarrhoea virus (BVDV) is an important viral agent causing the reproductive failure in cattle. The objectives of the study were to assess the role of male and female gametes, as carriers of cytopathic (CP) and non-cytopathic (NCP) BVDV to embryonic cells during in vitro fertilization. In this respect, sperm and oocytes were separately exposed to concentrations of 104.5 or 105.5 TCID50 /mL CP and NCP BVDV, for 2 h before fertilization. After washing, the intact gametes with the infected gametes were inseminated. Seven days post-fertilization, the virus-exposed embryos were examined for presence of the viral genome by RT-PCR. One-way anova with post-hoc Tukey's HSD test and an independent samples t-test were used to compare within and between groups, respectively. The results presented a significant decrease in the blastocyst rates for CP-infected groups than NCP-infected groups (p ≤ .01). Compared to the controls and the infected oocyte groups, the cleavage rates of the infected sperm groups (NCP and CP BVDV) were significantly reduced both in low (104.5 TCID50 /mL) and high (105.5 TCID50 /mL) titres of the virus (p ≤ .01). The proportion of embryos which was developed to blastocyst stages was significantly lower for CP and NCP-infected groups than the control groups (p ≤ .001). According to the molecular results, all samples of the retarded/degenerated embryos (at least one blastocyst within each one) in CP and NCP groups, one sample (at least one blastocyst in that) within a CP-infected group, and six samples (at least one blastocyst in each one of those) of NCP-infected groups contained the viral nucleic acid. Likewise, the results of viral enrichment showed all reactions in which RT-PCR were positive induced CPEs in MDBK monolayers. In conclusion, it is clear that CP and NCP BVDV were able to traverse zona pellucida during fertilization, and they had also negative effects on embryo development.

Importance of preovulatory estradiol on uterine receptivity and luteal function

Animals that exhibited estrus had greater pregnancy success compared to animals that did not exhibit estrus before fixed-time AI (FTAI). Estradiol is synthesized in bovine ovarian follicles under gonadotropin regulation and can directly and indirectly regulate the uterine receptivity and luteal function. Estradiol concentrations at FTAI impacted oviductal gene expression and has been reported to play an important role in establishing the timing of uterine receptivity. These changes have been reported to impact uterine pH and sperm transport to the site of fertilization. After fertilization, preovulatory estradiol has been reported to improve embryo survival likely by mediating changes in uterine blood flow, endometrial thickness and changes in histotroph. Cows with greater estradiol concentrations at the time of GnRH-induced ovulation also had a larger dominant follicle size and greater circulating progesterone concentrations on day 7. Therefore, it is impossible to accurately determine the individual benefit of greater estradiol concentrations prior to ovulation and greater progesterone concentrations following ovulation to pregnancy establishment, as these two measurements are confounded. Research has indicated an importance in the occurrence and timing of increasing preovulatory concentrations of estradiol, but increasing estradiol concentrations by supplementation may not be sufficient to increase fertility. Increased production of estradiol by the preovulatory follicle may be required to enhance fertility through the regulation of sperm transport, fertilization, oviductal secretions, the uterine environment, and embryo survival.

Use of MALDI-TOF mass spectrometry to explore the peptidome and proteome of in-vitro produced bovine embryos pre-exposed to oviduct fluid

In order to identify oviduct fluid (OF) peptides and proteins possibly uptaken by developing embryos, in-vitro produced bovine embryos exposed or not to OF were individually analyzed by MALDI-TOF mass spectrometry. Overall, 11 masses were overabundant in OF-treated embryos compared to controls, among which one at 8.9 kDa annotated as immediate early response 3-interacting protein 1 or a peptide of transitional endoplasmic reticulum ATPase met the criteria of an OF embryo-interacting protein or peptide.

A Comparative View on the Oviductal Environment during the Periconception Period

The oviduct plays important roles in reproductive events: sperm reservoir formation, final gamete maturation, fertilization and early embryo development. It is well known that the oviductal environment affects gametes and embryos and, ultimately, the health of offspring, so that in vivo embryos are better in terms of morphology, cryotolerance, pregnancy rates or epigenetic profile than those obtained in vitro. The deciphering of embryo-maternal interaction in the oviduct may provide a better understanding of the embryo needs during the periconception period to improve reproductive efficiency. Here, we perform a comparative analysis among species of oviductal gene expression related to embryonic development during its journey through the oviduct, as described to date. Cross-talk communication between the oviduct environment and embryo will be studied by analyses of the secreted or exosomal proteins of the oviduct and the presence of receptors in the membrane of the embryo blastomeres. Finally, we review the data that are available to date on the expression and characterization of the most abundant protein in the oviduct, oviductin (OVGP1), highlighting its fundamental role in fertilization and embryonic development.

Identification of 56 Proteins Involved in Embryo-Maternal Interactions in the Bovine Oviduct

The bovine embryo develops in contact with the oviductal fluid (OF) during the first 4–5 days of pregnancy. The aim of this study was to decipher the protein interactions occurring between the developing embryo and surrounding OF. In-vitro produced 4–6 cell and morula embryos were incubated or not (controls) in post-ovulatory OF (OF-treated embryos) and proteins were then analyzed and quantified by high resolution mass spectrometry (MS) in both embryo groups and in OF. A comparative analysis of MS data allowed the identification and quantification of 56 embryo-interacting proteins originated from the OF, including oviductin (OVGP1) and several annexins (ANXA1, ANXA2, ANXA4) as the most abundant ones. Some embryo-interacting proteins were developmental stage-specific, showing a modulating role of the embryo in protein interactions. Three interacting proteins (OVGP1, ANXA1 and PYGL) were immunolocalized in the perivitelline space and in blastomeres, showing that OF proteins were able to cross the zona pellucida and be taken up by the embryo. Interacting proteins were involved in a wide range of functions, among which metabolism and cellular processes were predominant. This study identified for the first time a high number of oviductal embryo-interacting proteins, paving the way for further targeted studies of proteins potentially involved in the establishment of pregnancy in cattle.

Sex Steroid-Mediated Control of Oviductal Function in Cattle

In cattle, the oviduct is a tubular organ that connects the ovary and the uterus. The oviduct lumen stages a dynamic set of cellular and molecular interactions to fulfill the noble role of generating a new individual. Specific anatomical niches along the oviduct lumen provide the appropriate microenvironment for final sperm capacitation, oocyte capture and fertilization, and early embryo development and transport. To accomplish such complex tasks, the oviduct undergoes spatially and temporally-regulated morphological, biochemical, and physiological changes that are associated with endocrine events of the estrous cycle. Specifically, elevated periovulatory concentrations of estradiol (E2) and progesterone (P4) influence gene expression and morphological changes that have been associated positively to fertility in beef cattle. In this review, we explore how E2 and P4 influence oviductal function in the beginning of the estrous cycle, and prepare the oviductal lumen for interactions with gametes and embryos.

Recombinant human oviductin regulates protein tyrosine phosphorylation and acrosome reaction

The mammalian oviduct synthesizes and secretes a major glycoprotein known as oviductin (OVGP1), which has been shown to interact with gametes and early embryos. Here we report the use of recombinant DNA technology to produce, for the first time, the secretory form of human OVGP1 in HEK293 cells. HEK293 colonies stably expressing recombinant human OVGP1 (rHuOVGP1) were established by transfecting cells with an expression vector pCMV6-Entry constructed with OVGP1 cDNA. Large quantities of rHuOVGP1 were obtained from the stably transfected cells using the CELLSPIN cell cultivation system. A two-step purification system was carried out to yield rHuOVGP1 with a purity of >95%. Upon gel electrophoresis, purified rHuOVGP1 showed a single band corresponding to the 120–150 kDa size range of human OVGP1. Mass spectrometric analysis of the purified rHuOVGP1 revealed its identity as human oviductin. Immunofluorescence showed the binding of rHuOVGP1 to different regions of human sperm cell surfaces in various degrees of intensity. Prior treatment of sperm with 1% Triton X-100 altered the immunostaining pattern of rHuOVGP1 with an intense immunostaining over the equatorial segment and post-acrosomal region as well as along the length of the tail. Addition of rHuOVGP1 in the capacitating medium further enhanced tyrosine phosphorylation of sperm proteins in a time-dependent manner. After 4-h incubation in the presence of rHuOVGP1, the number of acrosome-reacted sperm induced by calcium ionophore significantly increased. The successful production of rHuOVGP1 can now facilitate the study of the role of human OVGP1 in fertilization and early embryo development.

The influence of recombinant feline oviductin on different aspects of domestic cat (Felis catus) IVF and embryo quality

Oviductin is known to be a key player providing a convenient environment for the process of fertilization affecting this by direct interaction with oocytes and sperm. As in vitro embryo production in the context of assisted reproduction for endangered felids is still in the process of optimization, oviductin might be used to improve IVF results. Recombinant His-tagged feline oviductin was expressed by transformed Escherichia coli BL21DE3 cells. The protein was purified by immobilized metal ion affinity chromatography. The effect of the recombinant protein was characterized in three experiments: a hemizona assay for sperm binding analysis, the IVF outcome, and the relative mRNA expression levels in blastocysts after IVF. A significant higher number of bound sperm cells were found after incubation in oviductin. No significant effect on cleavage, morula, and blastocyst rates with or without oviductin incubation during IVF could be observed. However, the relative mRNA abundance of GJA1, a gene, whose expression level is known to be a marker of embryo quality, was significantly increased (P value less than 0.05) in blastocysts after oviductin treatment. In contrast to this, expression of OCT4, HSP70, DNMT1, DNMT3A, BAX, IGF1R, and GAPDH was not significantly affected. We assume that our recombinant oviductin in its current nonglycosylated form is able to enhance sperm binding. Despite of a missing significant effect on IVF outcome, embryo quality in terms of relative GJA1 expression is influenced positively. These promising results demonstrate the value of recombinant oviductin for the IVF in cats.

The role of nutrients, peptide growth factors and co-culture cells in development of preimplantation embryos in vitro

Our knowledge of the control of preimplantation embryo development and growth is deficient in many aspects as is evidenced by the great difficulty there is in growing embryos of many species in vitro while maintaining viability. This review discusses recent findings on the roles of nutrients, peptide growth factors and co-culture cells in embryo growth and development in vitro.

Structures and biosynthesis of the N- and O-glycans of recombinant human oviduct-specific glycoprotein expressed in human embryonic kidney cells

Oviduct-specific glycoprotein (OVGP1) is a major mucin-like glycoprotein synthesized and secreted exclusively by non-ciliated secretory cells of mammalian oviduct. In vitro functional studies showed that OVGP1 plays important roles during fertilization and early embryo development. We have recently produced recombinant human oviduct-specific glycoprotein (rhOVGP1) in human embryonic kidney 293 (HEK293) cells. The present study was undertaken to characterize the structures and determine the biosynthetic pathways of the N- and O-glycans of rhOVGP1. Treatment of the stable rhOVGP1-expressing HEK293 cells with either GalNAcα-Bn to block O-glycan extension, tunicamycin to block N-glycosylation, or neuraminidase increased the electrophoretic mobility of rhOVGP1. A detailed analysis of O- and N-linked glycans of rhOVGP1 by mass spectrometry showed a broad range of many simple and complex glycan structures. In order to identify the enzymes involved in the glycosylation of rhOVGP1, we assayed glycosyltransferase activities involved in the assembly of O- and N-glycans in HEK293 cells, and compared these to those from the immortalized human oviductal cells (OE-E6/E7). Our results demonstrate that HEK293 and OE-E6/E7 cells exhibit a similar spectrum of glycosyltransferase activities that can synthesize elongated and sialylated O-glycans with core 1 and 2 structures, as well as complex multiantennary N-glycans. It is anticipated that the knowledge gained from the present study will facilitate future studies of the role of the glycans of human OVGP1 in fertilization and early embryo development.

Sequence analysis of feline oviductin and its expression during the estrous cycle in the domestic cat (Felis catus)

Oviductins belong to a family of oviduct-specific glycoproteins believed to play an important role in fertilization and/or early embryonic development. Oviductin cDNA between species is highly conserved and shares 58% to 98% similarity in the deduced amino acid sequences. Our objective in this study was to sequence the full open reading frame of the feline oviductin and to examine its expression during the estrous cycle on both mRNA and protein level. The obtained cDNA containing the full open reading frame was determined to be 1677 nucleotides coding for a deduced protein of 558 amino acids. Identities between species range from 74% (mouse) to 80% (human, baboon, and rhesus) within the N-terminal protein region. Major differences were localized in the carboxy terminal region, which corresponds to exon 11 of the gene. Feline oviductin contained one putative N-linked glycosylation site, six O-linked glycosylation sites, a potential heparin binding site, and two cholesterol recognition and/or interaction amino acid consensus (CRAC) domains. Oviductin expression was analyzed by real time quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry. Both approaches revealed an estrous cycle-dependent expression in the ampulla and isthmus. Quantitative PCR showed highest oviductin mRNA copy numbers in the early and late follicular stage and reduced mRNA expression during all other stages. With the exception of the early follicular stage, feline oviductin mRNA abundance was not significantly different in the oviductal segments ampulla and isthmus. A prominent immunolabeling was seen in the early and late follicular stage which disappeared after ovulation, indicating a function of the protein during sperm storage and fertilization.

The secretions of oviduct epithelial cells increase the equine in vitro fertilization rate: are osteopontin, atrial natriuretic peptide A and oviductin involved?

BACKGROUND

Oviduct epithelial cells (OEC) co-culture promotes in vitro fertilization (IVF) in human, bovine and porcine species, but no data are available from equine species. Yet, despite numerous attempts, equine IVF rates remain low. Our first aim was to verify a beneficial effect of the OEC on equine IVF. In mammals, oviductal proteins have been shown to interact with gametes and play a role in fertilization. Thus, our second aim was to identify the proteins involved in fertilization in the horse.

METHODS & RESULTS

In the first experiment, we co-incubated fresh equine spermatozoa treated with calcium ionophore and in vitro matured equine oocytes with or without porcine OEC. We showed that the presence of OEC increases the IVF rates. In the subsequent experiments, we co-incubated equine gametes with OEC and we showed that the IVF rates were not significantly different between 1) gametes co-incubated with equine vs porcine OEC, 2) intact cumulus-oocyte complexes vs denuded oocytes, 3) OEC previously stimulated with human Chorionic Gonadotropin, Luteinizing Hormone and/or oestradiol vs non stimulated OEC, 4) in vivo vs in vitro matured oocytes. In order to identify the proteins responsible for the positive effect of OEC, we first searched for the presence of the genes encoding oviductin, osteopontin and atrial natriuretic peptide A (ANP A) in the equine genome. We showed that the genes coding for osteopontin and ANP A are present. But the one for oviductin either has become a pseudogene during evolution of horse genome or has been not well annotated in horse genome sequence. We then showed that osteopontin and ANP A proteins are present in the equine oviduct using a surface plasmon resonance biosensor, and we analyzed their expression during oestrus cycle by Western blot. Finally, we co-incubated equine gametes with or without purified osteopontin or synthesized ANP A. No significant effect of osteopontin or ANP A was observed, though osteopontin slightly increased the IVF rates.

CONCLUSION

Our study shows a beneficial effect of homologous and heterologous oviduct cells on equine IVF rates, though the rates remain low. Furthers studies are necessary to identify the proteins involved. We showed that the surface plasmon resonance technique is efficient and powerful to analyze molecular interactions during fertilization.

Effect of oviductal proteins on structural and functional characteristics of cryopreserved sperm in Murrah buffaloes

The present study was undertaken to elucidate the effect of non-luteal oviductal proteins on sperm characteristics in Murrah buffaloes. Oviducts from healthy buffaloes were collected immediately after slaughter and the oestrous cycle phase was determined as either luteal or non-luteal based on ovarian morphology. Non-luteal oviducts (n = 80) were flushed from the isthmic end of the oviduct with PBS, fluid was centrifuged at 10,000 g at 4 degrees C for 20 min and then dialysed and clarified. The supernatant obtained was lyophilized to concentrate the protein and stored at -20 degrees C till use. Sixteen good quality ejaculates from four Murrah buffalo bulls were collected using an artificial vagina. After fresh semen analysis, each ejaculate was split into two parts and extended in Tris-citrate-egg yolk glycerol dilutor. Part I of the split ejaculate was treated with non-luteal oviductal proteins at the dose rate of 1 mg/ml of diluted semen, while part II remained as control. The extended semen was equilibrated for 4 h at 5 degrees C, filled in 0.5 ml French straws, exposed to LN(2) vapour, plunged into LN(2) and then stored at -196 degrees C. The equilibrated and frozen-thawed semen was evaluated for sperm motility, viability, acrosomal integrity, cervical mucus penetration test and hypo-osmotic sperm swelling test (HOST). In frozen-thawed semen, the percentage of sperm motility, viability and acrosomal integrity was significantly (p < 0.05) higher in the treatment group compared to the control group. The incorporation of non-luteal oviductal proteins in the extender increased the ability of sperm to penetrate cervical mucus both after equilibration and the freeze-thaw process. Similarly, the proportion of sperm with intact plasma membrane, as revealed by HOST values, was also significantly (p < 0.05) higher in the treatment group (32.6%) than the control group (27%) in frozen-thawed semen. It was inferred that incorporation of non-luteal whole oviductal fluid proteins improved the sperm quality in frozen-thawed semen in Murrah buffaloes.

Surface mapping of binding of oviductin to the plasma membrane of golden hamster spermatozoa during in vitro capacitation and acrosome reaction

Oviductins are high-molecular-weight glycoproteins synthesized and secreted by nonciliated oviductal epithelial cells and have been shown to play a role in fertilization and early embryo development. The present study was carried out to examine the in vitro binding capacity of hamster oviductin to homologous sperm and to determine the sites of its localization in untreated, capacitated, and acrosome-reacted spermatozoa. Freshly prepared epididymal and capacitated sperm as well as acrosome-reacted sperm were incubated with oviductal fluid prepared from isolated hamster oviducts, fixed and then probed with a monoclonal antibody against hamster oviductin. Results obtained with pre-embedding immunolabeling experiments revealed binding of oviductin to the acrosomal cap and the apical aspect of the postacrosomal region. Immunolabeling of both regions appeared to be more intense in capacitated spermatozoa. Acrosome-reacted sperm showed an immunoreaction of moderate intensity over the postacrosomal region. The plasma membrane overlying the equatorial segment also exhibited a weak labeling. Quantitative analysis obtained with the surface replica technique indicated that oviductin had a higher binding affinity for the acrosomal cap than the postacrosomal region and that the binding of oviductin to the latter plasma membrane domain was enhanced during capacitation. Binding of oviductin to the postacrosomal region, however, was attenuated after acrosome reaction. Immunolabeling for oviductin was found to be the weakest over the equatorial segment regardless of the experimental conditions. The binding of hamster oviductin to specific membrane domains of the homologous sperm and the changes in its distribution during capacitation and acrosome reaction may be important for the function of hamster oviductin preceding and during fertilization.

Susceptibility of in vivo- and in vitro-produced porcine embryos to classical swine fever virus

The objective of this study was to investigate the susceptibility of in vivo- and in vitro-produced (IVP) porcine embryos to classical swine fever virus (CSFV). IVP zona pellucida (ZP)-intact porcine embryos (n = 721) were co-cultured with CSFV for 120 h. After washing according to the International Embryo Transfer Society guidelines (without trypsin) and transferring embryos to CSFV-susceptible porcine kidney cells (PK15 cell line), no virus was isolated. However, when 88 IVP ZP-intact porcine embryos were co-cultured with CSFV for only 48 h before being transferred to PK15 cells, virus was isolated in three of six replicates. Similarly, 603 in vivo-produced porcine embryos were co-cultured with CSFV for 120 h. Subsequently, CSFV was isolated in eight of 50 groups (16%) and the ability of these to form a blastocyst was significantly reduced when compared with the control group (68.2 +/- 19.9% vs 81.9 +/- 9.7%; p < or = 0.001). In contrast, the development of CSFV-exposed IVP porcine embryos was not affected when compared with control embryos (19.1 +/- 10.8% vs 18.9 +/- 10.6%; p > or = 0.05). After removal of the ZP of IVP embryos and subsequent co-culture with CSFV, the virus was isolated from all groups of embryos. These data suggest that virus replication had occurred in the embryonic cells. In conclusion, data indicate that in vivo- and in vitro-produced ZP-intact porcine embryos differ in their susceptibility to CSFV. Hatched or micro-manipulated embryos may increase the risk of transmission of CSFV by embryo transfer, which has to be confirmed by in vivo tests under isolation conditions.

Effects of human oviductal in vitro secretion on spermatozoa and search of sperm-oviductal proteins interactions

It has been suggested that oviductal proteins could be involved in modulating sperm function and fertilizing ability through as yet not well-known mechanisms. The objective of the study was to investigate the pattern of proteins secreted by human oviductal tissue cultures and the effects of their conditioned media (CM) on sperm function under capacitating conditions and in phosphate buffered saline (PBS). In addition, interactions between spermatozoa and oviductal proteins were examined. The oviductal tissue was obtained from pre-menopausal patients scheduled for hysterectomies because of uterine fibromyoma. Normozoospermic semen samples were obtained from healthy donors. Cultures of human fallopian tissue were carried out and CM were collected for analysis of the de novo production of [35S]-methionine-labelled proteins by SDS-PAGE. Motile spermatozoa were incubated under capacitating conditions and in PBS, with or without CM, and sperm fertilizing ability was assessed by ionophore-induced acrosome reaction (AR) and the acrosome reaction to ionophore challenge (ARIC) score. The ionophore-induced AR was evaluated by the Pisum sativum technique. Sixteen de novo produced proteins were detected in CM. One of these proteins (molecular weight 79 kDa) was detected in extracts from spermatozoa pre-incubated with CM. Sperm survival and motility were maintained in the presence of CM, although results showed a significant decrease in ARIC score (p < 0.05), with respect to controls. The presence of CM significantly decreased sperm fertilizing ability, without affecting sperm survival. These results suggest that the oviductal secretion could contribute to preserve sperm viability and motility, and to prevent a premature response of spermatozoa to AR inducers.

Cyclic Related and Pathological Changes in the Lectin-binding Sites on the Swine Oviduct

This study was carried out to compare the lectin-binding pattern in the normal and pathological oviduct of sows during the ovarian cycle. Lectin-binding patterns showed differences between segments, phases of ovarian cycle and presence of morphologic lesions. In the infundibulum, it was observed that the cysts, in the follicular phase, reduced Ricinus communis-I (RCA-I) and Ulex europaeus-I (UEA-I) binding. Furthermore, in the pathological oviducts of the luteal-phase group, there is a reduction of Concanavalia ensiformis (Con-A) reactivity in this segment of the tube having wall cysts, adenomyosis and diverticulus. The Arachis hypogaea (PNA) binding in the infundibulum, during the luteal phase, decreased in the tube having adenomyosis. In animals with wall cysts, the Con-A, Triticum vulgaris (WGA) and RCA-I reactivity was minor in the glycocalyx of the isthmus epithelium during follicular phase. Con-A and Dolichos biflorus (DBA) binding pattern was minor in the luteal-phase isthmus of the tube having wall cysts, adenomyosis and diverticulus. In the ampulla, the wall cysts impaired the Con-A reaction only in the basal region of the epithelium, in the follicular phase. Binding with Con-A was decreased in the ampulla of animals in the luteal phase in the tube lesions with cysts and diverticulus. In addition, the diverticulus observed in the ampulla, during the luteal phase, reduced the PNA tubaric binding. The results of this study showed that the morphologic alterations modify the sugar pattern in the oviduct of sows. These modifications in glycoconjugates may be one of the reasons for the failure of fertility in sows.

Evidence for the role of oviduct secretions in sperm function, fertilization and embryo development

The oviduct is a dynamic organ which facilitates gamete function, fertilization and embryo development. Secretions of the oviduct, recovered by tissue culture or cannulation techniques have been used to define the composition of the oviduct milieu, as well as functions associated with stage of the reproductive cycle or region of the oviduct. Several oviduct proteins have been shown to associate with the gametes and embryos. Ongoing studies are directed at identifying oviduct proteins and determining their function. Oviduct-specific glycoproteins (OSG) have been purified from the oviduct and shown in vitro to have positive affects on sperm capacitation, sperm-ovum binding, ovum penetration and embryo development. Osteopontin, another oviduct secretion, also has been shown to stimulate fertilization and embryo development. The picture emerging is that some components of the oviduct milieu have overlapping functions to collectively provide a failsafe system to ensure fertility in vivo so that success is not dependent on a single component.

Detection of nascent and/or mature forms of oviductin in the female reproductive tract and post-ovulatory oocytes by use of a polyclonal antibody against recombinant hamster oviductin

Oviductins belong to a family of glycoproteins that have been suggested to play several roles during the early processes of reproduction. Recently, a polyclonal antibody was raised against recombinant hamster oviductin (rhaOv(m)). Here the anti-rhaOv(m) antibody was used to investigate the sites of localization of oviductin in the female golden hamster. In the hamster oviduct, immunolabeling was restricted to the content of the Golgi saccules and secretory granules of the non-ciliated oviduct cells. After its release into the lumen, oviductin becomes associated with the zona pellucida of post-ovulatory oocytes. In unfertilized oocytes, oviductin was also detected in membrane invaginations along the oolemma and in some vesicles within the ooplasm. Furthermore, oviductin was detected over the microvilli and within multivesicular bodies of uterine epithelial cells. Western blotting analysis revealed the presence of oviductin in the hamster oviduct but not in the uterus or ovary. In the oviduct, the anti-rhaOv(m) antibody detected a polydispersed band corresponding to native oviductin (160-350 kD) and several lower molecular weight bands (<100 kD) corresponding to nascent and partially glycosylated forms of oviductin. The anti-rhaOv(m) antibody provides an additional tool for investigation into the cytochemical and biochemical properties of different forms of hamster oviductin in the female reproductive tract.

The current status and future of commercial embryo transfer in cattle

A commercially viable cattle embryo transfer (ET) industry was established in North America during the early 1970s, approximately 80 years after the first successful embryo transfer was reported in a mammal. Initially, techniques for recovering and transferring cattle embryos were exclusively surgical. However, by the late 1970s, most embryos were recovered and transferred nonsurgically. Successful cryopreservation of embryos was widespread by the early 1980s, followed by the introduction of embryo splitting, in vitro procedures, direct transfer of frozen embryos and sexing of embryos. The wide spread adoption of ethylene glycol as a cryoprotectant has simplified the thaw-transfer procedures for frozen embryos. The number of embryos recovered annually has not grown appreciably over the last 10 years in North America and Europe; however, there has been significant growth of commercial ET in South America. Within North America, ET activity has been relatively constant in Holstein cattle, whereas there has been a large ET increase in the Angus breed and a concomitant ET decrease in some other beef breeds. Although a number of new technologies have been adopted within the ET industry in the last decade, the basic procedure of superovulation of donor cattle has undergone little improvement over the last 20 years. The export-import of frozen cattle embryos has become a well-established industry, governed by specific health regulations. The international movement of embryos is subject to sudden and dramatic disturbances, as exemplified by the 2001 outbreak of foot and mouth disease in Great Britain. It is probable that there will be an increased influence of animal rights issues on the ET industry in the future. Several companies in North America are currently commercially producing cloned cattle. The sexing of bovine semen with the use of flow cytometry is extremely accurate and moderate pregnancy rates in heifers have been achieved in field trials, but sexed semen currently is available in only a few countries and on an extremely limited basis. As of yet, all programs involving the production of transgenic cattle are experimental in nature.

In vivo versus in vitro oviductal glycoprotein (OGP) association with the zona pellucida (ZP) in the hamster and baboon

The goal of this study was to determine if differences exist between in vivo vs. in vitro OGP association with the ZP and to quantitate those differences. Ovarian oocytes were harvested 12.5 or 27 hr post-hCG from hyperstimulated hamsters or baboons, respectively. Hamster and baboon ovarian oocytes were incubated in vitro in media +/- homologous OGP (100 or 200 microg/100 microl) or in some studies with 100 microl oviductal fluid for 3, 6, or 24 hr at 37 degrees C. Some of the baboon ovarian oocytes were transferred immediately after harvesting to the ampulla of both oviducts using a tom cat catheter and retrieved after a 3 hr in situ incubation. Hamster oviductal oocytes were collected 3, 6, and 24 hr following ovulation. After incubation or oocyte retrieval from the oviduct, cumulus cells were removed, oocytes were washed extensively and binding of OGP to the ZP was examined by immunofluorescence. Fluorescence intensity was quantified using densitometric scanning of photographic negatives with the background of each negative as an internal control. In all studies, OGP association with the ZP was significantly greater in vivo than in vitro (P < 0.05). In vitro OGP association with the ZP did not significantly increase with incubation time or OGP concentration; however, a small nonsignificant increase in OGP association with the ZP in the oviduct was detected over time. Differences did not appear to be due to depletion of OGP from the in vitro incubation media, since Western blot analysis of the media showed that OGP was still present. Although OGP concentration in vivo is unknown, Western blots showed similar intensity comparing 100 microg of OGP media and oviductal fluid. Immunolocalization of OGP using laser confocal microscopy showed regional differences in OGP binding. The outer half of the zona pellucida had significantly more OGP bound than the inner half on oviductal oocytes. No regional differences were detected for in vitro incubated oocytes. In conclusion, OGP association with the ZP is greater in vivo vs. in vitro, suggesting that one must be cautious in designing and evaluating in vitro studies of OGP function.

Structural aspects of the zona pellucida of in vitro-produced bovine embryos: a scanning electron and confocal laser scanning microscopic study

Structural aspects of the bovine zona pellucida (ZP) of in vitro-matured (IVM) oocytes and in vitro-produced (IVP) embryos were studied in two experiments to find a tentative explanation for the zona's barrier function against viral infection. In Experiment 1, the ultrastructure of the outer ZP surface was studied. The diameter (nm) and the number of the outer pores within an area of 5000 microm(2) of 10 IVM oocytes, 10 zygotes, 10 8-cell-stage embryos, and 10 morulae were evaluated by scanning electron microscopy. In oocytes and morulae, the ZP surface showed a rough and spongy appearance with numerous pores. In zygotes, the ZP surface was found to have a smooth, melted appearance with only a few pores. In 8-cell-stage embryos, both surface patterns were found. The mean number (per 5000 microm(2)) and the mean diameter of the outer pores were different between the four stages of development (P < 0.001): 1511 pores in oocytes, 1187 in zygotes, 1658 in 8-cell-stage embryos, and 3259 in morulae, with mean diameters of 182, 223, 203, and 155 nm, respectively. In Experiment 2, the continuity of the meshes (network of pores) towards the embryonic cells was examined by confocal laser scanning microscopy. Therefore, the passage through and the location in the ZP of fluorescent microspheres, with similar dimensions as bovine viral diarrhea virus (BVDV, 40-50 nm) and bovine herpesvirus-1 (BHV-1; 180-200 nm), were evaluated. For all stages, the smallest beads were detected halfway through the thickness of the ZP, whereas the beads with a size of 200 nm were found only within the outer-fourth part of the ZP. It can be concluded that the intact ZP of bovine IVM oocytes and IVP embryos are constructed in such a way that BVDV and BHV-1 should not be able to traverse the ZP and reach the embryonic cells. However, the risk exists that viral particles can be trapped in the outer layers of the ZP.

Effects of porcine follicular fluid and oviduct-conditioned media on maturation and fertilization of porcine oocytes in vitro

Advances in porcine in vitro fertilization have been impaired by low normal fertilization rates resulting from a high rate of polyspermy. The present study was undertaken to determine the effects of porcine follicular fluid (pFF) and oviductal explant-conditioned medium on maturation and fertilization of porcine oocytes in vitro. Oocytes and pFF were collected from small, medium, and large follicles and pooled within size category. Maturation and fertilization media were supplemented (10%) with either fetal calf serum (FCS) or pFF (either fresh or snap-frozen). Snap-frozen pFF from small (3.1-5.0 mm) and medium (5.1-7 mm) follicles, respectively, increased maturation rates of oocytes from small and medium follicles by nearly 36% (p < 0.05) compared with those treated with FCS or fresh pFF. Supplementing media with either fresh or snap-frozen pFF from medium follicles reduced (p < 0.05) polyspermy of oocytes from small follicles by 30% compared with supplemental FCS. Snap-frozen pFF increased (p < 0.05) normal fertilization compared to that in fresh pFF (29% vs. 18%). Supplementing oocytes from medium follicles with snap-frozen pFF yielded the lowest (18%, p < 0.05) polyspermy rate. Oocytes from both small and medium follicles supplemented with pFF and/or conditioned medium (CM) from oviducts of periovulatory gilts exhibited a 95% improvement in normal fertilization rate and a 34% decrease in polyspermy rate compared to those treated with FCS (p < 0.05). CM from oviducts of luteal gilts did not improve rates of polyspermy and normal fertilization (p > 0.05). We conclude that snap-frozen follicular fluid from medium follicles and CM from cultured oviducts of periovulatory gilts improve in vitro maturation, reduce polyspermy, and increase normal fertilization rates in vitro.

Identification of ampullary and isthmic oviductal fluid proteins that associate with the bovine sperm membrane

The objective of this study was to define the complement of ampullary and isthmic oviductal fluid proteins that associate with the sperm membrane during the non-luteal and luteal stages of the oestrous cycle. Oviductal fluid was obtained from three dairy cows via indwelling cannulae in the ampulla and isthmus of the same oviduct. Daily samples of oviductal fluid were combined by region and stage of the cycle to create pools consisting of non-luteal isthmic, luteal isthmic, non-luteal ampullary, and luteal ampullary oviductal fluid. An aliquot from each oviductal fluid pool was biotinylated by incubation in biotin reagent. Spermatozoa from three fertile bulls were pooled, washed and incubated for 4 h in each of the four pools of biotinylated oviductal fluid. After incubation, sperm membrane proteins were solubilized, and proteins subjected to one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis and western blotting. The biotinylated oviductal fluid proteins that associated with the sperm membranes were detected by avidin-horseradish peroxidase and diaminobenzidine substrate. Eight oviductal fluid proteins with apparent molecular weights of 97, 75, 66, 55, 48, 34, 28 and 24 kDa were consistently detected to associate with the sperm membrane. Differences in ampullar and isthmic fluid proteins that associated with sperm during the luteal and non-luteal stage of the oestrous cycle were not detected.

A novel regulation of the oviductal glycoprotein gene expression by luteinizing hormone in bovine tubal epithelial cells

The hypothesis that bovine oviductal epithelial cells contain luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptors and LH may regulate the oviductal glycoprotein (OGP) gene expression was tested. The results showed that bovine oviductal epithelial cells contain an 80 kDa LH/hCG receptor protein which can bind [(125)I]hCG. Culturing these cells with highly purified hCG, used as a surrogate hormone for LH, resulted in a dose and time dependent increase in a 95 kDa protein and a 2.3 kb transcript of OGP. The maximal increase of 100% was obtained with 10 ng/ml hCG and after three days of culture. LH, but not other hormones in the glycoprotein hormone family, isolated subunits of hCG, estradiol-17beta or progesterone, mimicked hCG, suggesting that the effect is hormone specific and requires the conformation of native hormone. The increase in steady state OGP mRNA levels by hCG is not due to an increase in the transcription rate of the gene. It is rather due to a significant increase in the half-life of OGP transcripts from 23 h in the control to 28 h after treatment with hCG. In summary, we conclude that LH and hCG can increase the synthesis of OGP by decreasing the degradation of its transcripts in bovine oviductal epithelial cells. Since OGP may play important roles in fertilization and growth and development of early embryo, higher LH levels present during the periovulatory period may directly participate in the early pregnancy events through increasing the synthesis of OGP.

Fate of hamster oviductin in the oviduct and uterus during early gestation

Oviductins are a family of glycoproteins which are synthesized and secreted by oviductal secretory cells and which, upon their secretion in the lumen of the oviduct, become associated with postovulatory oocytes and developing embryos. Recently, we showed that hamster oviductin is maximally secreted in the oviduct at the time of ovulation and is later associated with a certain population of uterine epithelial cells, where it is subsequently endocytosed and degraded. In light of these results, this study was conducted to follow the fate of hamster oviductin in the oviduct and uterus during early gestation. Using a monoclonal antibody against hamster oviductin, immunofluorescence and immunogold labeling revealed that during early gestation, immunoreactivity to oviductin in the uterus gradually diminished to an almost total disappearance at time of implantation. However, the strong labeling intensity remained unchanged in the oviduct. Biochemical analyses demonstrated that a degradation of oviductin occurs in the uterus, and a loss of immunoreactivity was also observed as gestation progressed, so that by the time of implantation, immunoreactivity to oviductin was barely detectable. The decrease of oviductin along the uterine epithelium at the time of blastocyst attachment and its final disappearance at implantation suggest that this glycoprotein could be a potential modulator of uterine receptivity.

Lectin binding patterns of porcine oviduct mucosa and endometrium during the oestrous cycle

Important functions of the oviduct during reproduction include the provision of an optimal environment for gametes and zygotes and nutrition of the early embryo. These functions are ensured by the secretion of an oviductal fluid which is known to contain organ-specific glycoproteins. Glycoconjugates of the apical glycocalyx are considered to play a major role in cell recognition and interaction processes. In the present investigation, binding patterns of Con A, HPA, LTA, RCA I, UEA I, and WGA were studied in defined segments of the oviduct (infundibulum, ampulla, isthmus) and in the uterus during the oestrous cycle. The carbohydrate distribution showed regional as well as time dependent differences. LTA, HPA and WGA reacted strongly with Golgi regions and secretory granules in the oviduct epithelium during the follicular phase, indicating high secretory activity. LTA, HPA, and UEA I also revealed a varying carbohydrate composition of the glycocalyx during the oestrous cycle. Prominent regional differences in glycoconjugate expression were shown in oviductal segments by LTA and HPA binding: during the follicular phase, LTA binding sites were only present on epithelial cells of the isthmic segment, the ampulla and infundibulum being unreactive. D-N-acetyl-galactosamine residues were demonstrated on ciliated epithelial cells of the ampulla and infundibulum exclusively during oestrus. The glycocalyx of uterine epithelial cells was clearly defined by HPA, WGA, LTA, RCA I and UEA I; LTA binding was restricted to the secretory phase. The observation of regional and time dependent variability in glycoconjugate distribution strongly indicates their specific physiological functions in reproductive processes.

Modifications of the lectin binding pattern in the rat zona pellucida after in vivo fertilization

The zona pellucida (ZP) is an extracellular matrix surrounding the mammalian oocyte. It is involved in the sperm-egg adhesion phenomenon, induces the acrosome reaction, and participates in the late blockage to polyspermy. Thus, during the process of fertilization the cortical reaction is induced and the biochemical and biological properties of the ZP are modified. Some of these changes have been suggested to prevent the polyspermy. However, the mechanisms behind most of these changes are not well understood. Carbohydrate residues of the ZP glycoproteins have been shown to play a key role in the early step of fertilization. In the present study, the changes produced in the terminal oligosaccharide sequences of the rat ZP glycoproteins after in vivo fertilization were investigated by means of lectin-gold cytochemistry. A comparative quantitative analysis of the density of labeling in the ZP before and after fertilization was carried out by automatic counting of gold particles. The ZP of fertilized and unfertilized eggs were labeled by a battery of lectins including PNA, LFA, MAA, AAA, DSA, RCA I, and WGA. For all lectin studied in both fertilized and unfertilized eggs the labeling was preferentially located in the inner region of the ZP. After fertilization, binding of PNA, LFA, MAA, AAA, and DSA decreased in both inner and outer regions of the ZP. Labeling of RCA I-binding sites only decreased in the inner ZP, whereas reactivity to WGA was increased in the inner ZP, whereas reactivity to WGA was increased in the inner area of the ZP. Digestion of the thin-sections with neuraminidase prior to labeling with WGA resulted in a decrease of labeling for WGA binding sites. However, the labeling density of WGA binding sites was similar in both unfertilized and fertilized eggs upon treatment with neuraminidase. The present results demonstrate that the oligosaccharide chains contained in the rat ZP are modified after fertilization of the oocyte. Cortical granules of the oocytes might be involved in these modifications by two mechanisms: 1) by hydrolysis of terminal carbohydrate residues of ZP glycoproteins by specific glycosidases contained in the granules; and 2) by addition of new glycoproteins to the ZP after the exocytosis of the cortical granules (cortical reaction).

Importance of calcium for the binding of oviductal fluid proteins to the membranes of bovine spermatozoa

Our laboratory has recently shown that in vitro-cultured oviductal cells secrete sperm motility maintaining factor(s). Since the binding of oviductal proteins to spermatozoa (SPZ) has been demonstrated in many species, the motility factor was postulated to bind the membranes of SPZ. Therefore, the current study was performed to evaluate which proteins from in vivo oviductal secretions bind to sperm membranes, to characterize binding conditions, and to evaluate the effect of this binding on sperm survival. Bovine oviducts were dissected, and oviductal cells and fluid were collected by pressing the oviductal tube with a glass slide. This mixture was incubated in Tris-EDTA buffer at 37 degrees C for 30 min, and the cells were washed twice by centrifugation. The supernatant containing oviductal fluid proteins (OFP) was reserved, filtered, frozen (for later motility tests), or lyophilized and labeled with 125I. Frozen-thawed SPZ were incubated either immediately, following capacitation, ionophore-induced acrosome reaction, death by heating, or flagellar removal with labeled OFP for 30 min. The resulting pellet after three washes was dissolved in SDS and submitted to 10% SDS-PAGE. An autoradiogram showed that 72, 66, 39, 38, and 36 kDa proteins bind strongly to the five types of SPZ used, and that this binding is very specific, since unlabeled OFP inhibited binding while serum proteins did not. Furthermore, for 39, 38, and 36 kDa proteins, the presence of calcium in the incubation medium was essential for dose-dependent binding, whereas magnesium was not. Preincubation of SPZ for 30 min at 37 degrees C with oviductal fluid, followed by one wash and 6 hr of incubation in control media, showed that the percentage of motile SPZ is significantly higher (52 +/- 6%) compared with SPZ not preincubated with oviductal fluid (24 +/- 6%; P < 0.01). In summary, a limited number of proteins from oviductal secretions bind to the surface of bovine SPZ only in the presence of calcium, and this binding appears to be important for subsequent sperm viability.

Kinetics of sperm penetration and fertilization in vitro in hamster follicular and oviductal ova

This study compared kinetics of in vitro sperm penetration and fertilization of in vivo matured follicular vs. oviductal hamster ova. Monospermic fertilization in cumulus-intact (C+) and cumulus-free (C-) follicular ova was highest at sperm concentrations of approximately 50 and 1.0 x 10(4) sperm/ml, respectively. The cumulus layer was a barrier to sperm penetration, but penetration of C-follicular ova was still lower than with C-oviductal ova. At 1 h of sperm:egg coincubation, 21% of C- follicular ova was penetrated vs. 77% of C- oviductal ova, while by 4 h these values were 71% and 98%, respectively. In contrast, activation of zona-free follicular and oviductal ova was not different (83-99%). However, at 2 h male pronuclear formation was lower in follicular ova (9%) than in oviductal ova (26%, P < 0.05). To test the hypothesis that lower and slower penetration with follicular ova compared with oviductal ova is due to lack of oviductal exposure, effects of hamster periovulatory oviductal fluid on penetration and fertilization kinetics of C- follicular ova were examined. Adding oviductal fluid did not improve penetration of follicular ova to levels equivalent to oviductal ova, but 3 h preincubation of follicular ova with oviductal fluid improved both zona penetration and male pronucleus formation to levels equivalent to those in oviductal ova. We conclude that kinetics of sperm penetration and fertilization in follicular ova are retarded, that these deficiencies derive from lack of ovum modulation by oviductal secretions, and that prolonged oviductal exposure of ova is essential for achieving full competence.

Oviductal protein produces fluorescence staining of the perivitelline space in mouse oocytes

Mouse oocytes were previously observed to undergo structural changes involving the perivitelline space (PVS) within the oviduct following ovulation, as visualized by staining with fluorochrome-protein conjugates. In the present study, this phenomenon was investigated in detail to determine the role of the oviduct and oocyte. Mouse ovarian oocytes matured in vitro were further incubated in medium or within explanted oviducts in vitro for varying periods of time and then stained with fluorescein isothiocyanate (FITC)-casein. Twenty percent of oocytes incubated within explanted oviducts for 3 hr showed distinct fluorescence staining of the PVS, whereas after 20 hr incubation, most (89%) oocytes were similarly stained. In contrast, no ovarian oocytes was stained when incubated in medium alone. Puromycin treatment during incubation of oocytes within explanted oviducts produced a dose-dependent decrease in the percentage of oocyte exhibiting PVS staining after FITC-casein exposure. FITC-casein staining of the PVS also occurred in all oocytes following incubation of in vitro-matured oocytes with oviductal tissue extract. In contrast, no oocytes incubated with serum exhibited fluorescence staining. Additionally, the PVS of oocytes failed to stain after incubation with either 0.001% of trypsin- or heat-treated oviductal homogenate. When zona pellucida (ZP) ghosts, devoid of ooplasm, were incubated within explanted oviducts, their PVS was stained brightly following FITC-casein treatment. From these results, it is concluded that proteinaceous material(s) secreted by the mouse oviduct is responsible for the fluorescence staining of the PVS of mouse oocytes and of ghost ZP. The ooplasm does not appear to play any role in altering the properties of the PVS staining.

Hypotaurine and taurine in gamete and embryo environments: de novo synthesis via the cysteine sulfinic acid pathway in oviduct cells

Taurine and hypotaurine seem to be important compounds for sperm survival and capacitation, the fertilisation process and embryo development, and are present in both sperm and genital secretions. Hypotaurine has protective effects against peroxidative damage. We have established a simple method for hypotaurine quantification in sperm and genital secretions. The mean concentration of hypotaurine is significantly higher in bovine than in human spermatozoa and in seminal plasma. We observed that both molecules are secreted by cow, sow, goat and rabbit oviduct epithelial cell monolayers. In rabbit the release is ascorbic acid dependent. Goat oviduct epithelial cells are able to use the transsulfuration pathway to form hypotaurine and taurine from methionine. We were able to identify cysteine sulfinate decarboxylase (EC 4.1.1.29) activity in cow and goat tubal monolayers. Our results demonstrate that hypotaurine and taurine are secreted by oviduct epithelium, and synthesised by tubal cells via the cysteine sulfinic acid pathway. The data obtained emphasise the importance of hypotaurine and taurine for gamete maturation, fertilisation and early embryonic development.

Bovine oviduct-specific glycoprotein: a potent factor for maintenance of viability and motility of bovine spermatozoa in vitro

In the cow, a specific glycoprotein--bovine oviduct-specific glycoprotein (BOGP)--is secreted by the epithelial cells of the oviduct at the follicular stage of the estrous cycle. In this study, we examined the effects of purified BOGP on the viability and motility of bovine spermatozoa in culture in vitro. Frozen-thawed bovine spermatozoa were incubated in modified Tyrode's solution (TALP) that contained purified BOGP (TALP-BOGP). In TALP-BOGP, both the viability and motility of bovine spermatozoa were more effectively maintained than in the control medium without any added protein. The increases in both the viability and motility of spermatozoa were dose-dependent. Spermatozoa were also incubated in TALP medium supplemented with bovine serum albumin, egg albumin, lactalbumin, or gastric mucin, and their viability and motility in these media were compared with that in TALP-BOGP. Both the viability and motility of spermatozoa were more effectively maintained in TALP-BOGP throughout a 12-hr incubation than in other media tested. An immunolabeling study demonstrated that a monoclonal antibody specific for BOGP reacted with the posterior region of the head, the middle portion, and the tail of spermatozoa that had been incubated with TALP-BOGP, suggesting that BOGP becomes specifically associated with particular regions of the spermatozoon. These results suggest that BOGP is a potent factor for maintenance of the viability and motility of sperm. On the basis of the present results, we also propose that BOGP may play an important role in sperm functions during the reproductive process.

Functions of proteins secreted by oviduct epithelial cells

Studies on embryonic development in vitro as well as observations in vivo, suggested that two aspects of oviduct physiology are important for early development. On one side has to be considered the oviduct "environment": temperature, pH, osmotic pressure, nutrients, oxygen tension, free radical scavengers, etc. On the other, the oviduct "active components": stimulatory and/or regulatory molecules, supposed to finely regulate the fertilisation process and the first differentiative steps. While the physical environment of the oviduct has been under investigation for some decades, studies on oviduct-specific molecules and their functions have only been developed much more recently. The amount of information on this topic, however, has rapidly reached the size that demands a summary. In this review the descriptive literature on oviduct specific proteins will be examined as a basis for illustrating the possible functions of these molecules. In particular their role in fertilisation and early embryonic cleavages will be analysed in some details. Finally a section is devoted to the presence and physiological significance of growth factors in oviduct fluid.

Steroidal and growth factor regulation of [3H]thymidine incorporation by cultured endosalpingeal cells of the bovine oviduct

Cultured cells from the bovine endosalpinx were used to evaluate effects of estradiol-17 beta, progesterone, epidermal growth factor, and insulinlike growth factors I and II on [3H]thymidine incorporation. Cells were treated with hormones and growth factors when approximately 50% confluent. After 24 h, DNA synthesis was quantified by pulsing cells with [3H]thymidine for 12 h and determining uptake into DNA. Cells prepared by mechanical dispersal incorporated more [3H]thymidine than cells dispersed with collagenase. However, hormonal responses were the same for both types of cells. As compared to plastic, cells on a Matrigel substratum exhibited lower incorporation of [3H]thymidine and were unresponsive to hormones. Estradiol-17 beta increased [3H]thymidine incorporation slightly at 10(-10) mol/liter and higher. Epidermal growth factor, insulinlike growth factor-I, and insulinlike growth factor-II also stimulated [3H]thymidine incorporation. Effects of insulinlike growth factor-I were greater for cells treated with estradiol-17 beta. In the absence of estradiol, progesterone inhibited [3H]thymidine incorporation at 1, 10, and 100 ng/ml. When estradiol-17 beta was present, progesterone stimulated [3H]thymidine incorporation at 1 ng/ml and reduced incorporation at 100 ng/ml. In conclusion, [3H]thymidine incorporation by cultured oviductal endosalpingeal cells can be regulated by ovarian steroids and growth factors. These molecules may represent signals through which the ovary, embryo, and oviduct regulate oviductal growth.

Hormonal control of the biosynthesis of hamster oviductin

In several mammalian species, the epithelial secretory cells of the oviduct synthesize and secrete specific glycoproteins that become associated with the zona pellucida of the ovulated oocyte. These glycoproteins are collectively designated as oviductins. A monoclonal antibody directed against hamster oviductin was used to study the ontogeny of this glycoprotein. Indirect immunofluorescence experiments performed on sections of hamster oviduct revealed that the glycoprotein begins to be secreted in 10-day-old females and that all of the oviductal secretory cells showed fluorescent staining by day 14. The intensity of the immunofluorescence reaction reached a maximum in the 28-day-old females. The oviducts of the 7-day-old hamster incorporated [35S]methionine in vitro into several proteins; however, the production and secretion of detectable amounts of radiolabeled oviductin only began at 14 days of age and reached a maximum at day 28 of age. It appears that the ontogeny of oviductin parallels the hormone dependent changes leading to sexual maturation and that its maximum secretion is already established at the time of the first ovulatory cycle. These results are substantiated by the fact that the production of oviductin is induced in estradiol-treated, but not progesterone or non-treated prepubertal animals, as determined by indirect immunofluorescence experiments.

Oviduct during early pregnancy: hormonal regulation and interactions with the fertilized ovum

The cyclic fluctuations in circulating levels of 17 beta-estradiol and progesterone that occur during the menstrual or estrous cycle are responsible for dramatic, cyclic changes in the epithelial lining and secretory status of the mammalian oviduct. The timely transition in the synthesis and release of oviduct proteins, due to the ovarian steroids, and their interactions with oocytes, sperm, and the fertilized ovum underscore key biological events during gamete interactions and early embryonic cleavage. The regulation of these secretory alterations during the first few days of pregnancy is discussed with respect to the influence of the ovarian steroids, their interactions with the embryo microenvironment, and the possible ways in which they may mediate the critical reproductive events of fertilization and embryo development.

Elaboration of an oviductin by the oviductal epithelium in relation to embryo development as visualized by immunocytochemistry

The hamster oviduct secretes a high molecular weight antigen that belongs to the family of glycoproteins known as oviductins. In the present study, using immuno-electron microscopy, we examined the location of this hamster oviductin-1 (Hm Ov-1) in hamster oviductal oocytes and early embryos up to the blastocyst stage. The immunoreactive pattern of Hm Ov-1 changes markedly during the embryo development. In oviductal oocytes prior to fertilization, Hm Ov-1 was associated exclusively with the zona pellucida. Following fertilization, immunolabeling was detected in the perivitelline space and over the plasma membrane of 2-cell, 4-cell, and 8-cell embryos as well as young blastocysts. The change of the immunoreactive pattern was accompanied by the formation of an abundant number of coated pits, endocytic vesicles, multivesicular bodies, and lysosomal-like structures which were strongly labeled by gold particles. These immunogold-labeled cytoplasmic organelles characteristic of the endosomal-lysosomal apparatus were particularly evident in 2-cell, 4-cell, and 8-cell embryos and showed a decrease in number in the blastocysts. The close resemblance between the labeled flocculent material detected in the perivitelline space and that found in the zona matrix of early embryos and blastocysts suggested that the Hm Ov-1-associated electron-dense, flocculent material in the perivitelline space originated from the zona pellucida and was later endocytosed by the blastomeres through coated pits and endocytic vesicles. The detection of Hm Ov-1 in numerous multivesicular bodies and lysosomal structures indicated that the oviductin is eventually degraded. Although the exact functional role of Hm Ov-1 is not known, the presence of a copious amount of Hm Ov-1 in early hamster embryos may be ascribed to a special relationship between this particular oviductin and embryo development.

Isolation, culture, and characterization of equine oviduct epithelial cells in vitro

Oviduct epithelial cells (OEC) increasingly are used to support embryonic development and to study gamete interactions with the female reproductive tract in vitro. This series of experiments was designed to characterize monolayers derived from oviduct epithelium. Epithelial cells harvested from the isthmus and ampulla of the oviducts of five estrous mares were cultured with or without the basal lamina extract, Matrigel. Within each group OEC were cultured in the presence of either estradiol-17 beta or a carrier control. All groups were subcultured three times. Epithelial cell morphology and function were examined by microscopy, analysis of secreted proteins, and immunocytochemistry. Epithelial cells attached more rapidly and reached confluence sooner when cultured on Matrigel than in uncoated wells. Cells showed variable evidence of ciliary activity up to 12 days in primary culture. Cells grown on Matrigel had a more polarized appearance in primary culture than those in uncoated wells, although no morphologic difference between anatomic site of origin or between steroid treated groups was noted. Anatomic site of origin had no effect, and steroid treatment had minimal effects, on patterns of secreted proteins. However, some differences were noted in protein secretion between cells grown with or without Matrigel. These data suggest that culture substrate may affect structure and function of OEC monolayers.

Oviductins possess chitinase- and mucin-like domains: a lead in the search for the biological function of these oviduct-specific ZP-associating glycoproteins

Over the last 10 years considerable progress has been made in the immunological and biochemical characterization of oviduct-specific glycoproteins. It is now well established that a subclass of these secretory products, designated as oviductins, associate with the zona pellucida of the ovulated oocyte and with the early embryo. Recent reports on the cloning of cDNAs of oviductins from various species, including that of golden hamster (Mesocricetus auratus) oviductin by our laboratory, allowed us to compare their deduced amino acid sequences with those of other proteins. Optimal alignment analysis showed that oviductins contain regions of significant similarity with catalytically inactive mammalian members of the bacterial and microfilarial chitinase protein family. Most importantly, a close examination of the hamster and human deduced amino acid sequences revealed that both glycoproteins possess contiguous Ser/Thr rich repeated units, clustered in their carboxy-terminal portions. These mucin-type motifs are similar in the hamster and human glycoprotein, although hamster oviductin contains more of these complete units. This striking feature might indicate that these molecules play a similar role to mucin-type glycoproteins, e.g., in protecting the oocyte and early embryo against attacks from their environment. We propose a model whereby oviductins are targeted to the oocyte via the interaction of their chitinase-like domains with specific oligosaccharide moieties of the zona pellucida. Once localized to this structure, oviductin molecules would act as a protective shield around the oocyte and early embryo by virtue of their densely glycosylated mucin-type domains.

Immunological detection and characterization of an estrus-associated antigen in the goat oviduct

The present study was designed to investigate the possibility that the goat oviduct produces specific substance(s) similar to the oviductal glycoprotein (BOGP) of the bovine oviduct. Oviductal flushings obtained from goats at the follicular and luteal phases of the estrous cycle were examined by immunoblotting for the presence of material that cross-reacted with monoclonal antibodies (MAbs) specific for BOGP. The MAbs immunoreacted with a broad band with a molecular mass of protein of about 97 kDa in the flushings of goat oviducts after fractionation of proteins by electrophoresis under reducing conditions. The antigen was present in flushings obtained from the ampullar segments of oviducts from goats at the follicular stage, but this antigen could hardly be detected in the flushings from the ampulla at the luteal phase and or the flushings from the isthmus at either the follicular or the luteal phase. This antigen was not detected in uterine flushings, follicular fluid, or serum. An immunohistochemical study demonstrated that the MAbs reacted specifically with the epithelial cells of the goat oviduct. Intense labeling was observed in the ampullar and fimbrial epithelia of goat oviducts at the follicular phase, but the immunohistochemical reaction was very weak at the luteal phase. In the isthmus, the reaction was faint during both the follicular and the luteal phase. No specific immunohistochemical reactivity with the MAbs was observed with other tissues from the reproductive tract or with nonreproductive tissues. Immunofluorescent staining showed that the antigen was associated with the zona pellucida of goat ovarian eggs that had been incubated with ampullar flushings from goats at the follicular stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical characterization of a bovine oviduct-specific sialo-glycoprotein that sustains sperm viability in vitro

A bovine oviduct-specific glycoprotein (BOGP) that sustained the viability of bovine spermatozoa in vitro was purified from an extract of bovine oviducts. The amino-terminal amino acid sequence of BOGP was found to be a homologous with that of oviductin, a protein from hamster that was recently characterized by Mallete and Bleau (1993: Biochem. J. 295, 437-445). Purified BOGP was characterized as a sialo-glycoprotein containing N-linked and O-linked sialo-oligosaccharides side chains with galactose, mannose, N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, fucose and sialic acids in its core protein (57 kDa). Intact BOGP has a wide range of isoelectric points (pIs) from 6.5 to 3.0 but a narrow range of molecular masses around 95 kDa. On isoelectric focusing of neuraminidase-treated BOGP (AS-BOGP), a narrow band with a pI of 9.3 was observed, and the ability of AS-BOGP to maintain sperm viability was negligible. We propose that BOGP is a mucin-type sialo-glycoprotein with a molecular mass of 72 kDa that contains one N-linked and approx. 15 O-linked sialo-oligosaccharide chains. These side chains appear to be important for the maintenance of sperm viability.

Stage-specific immunolabeling for oviductin in the secretory granules of the oviductal epithelium of the golden hamster during the estrous cycle

BACKGROUND

We have previously localized an antigen of oviductal origin in the zona pellucida of postovulatory hamster ova. This antigen is a high molecular weight glycoprotein secreted by the non-ciliated secretory cells of the oviduct and is later transferred to the zona pellucida of the oocyte during oviductal transit. This glycoprotein is rich in N-acetyl-D-galactosamine residues and has been designated Hamster Oviductin-1. In the present study, a monoclonal antibody (MAb) raised against this oviductin was used to detect the presence of this antigen in oviductal tissue during the estrous cycle.

METHODS

Twenty mature female golden hamsters were used and were divided into five groups of five animals each according to the five different stages of the estrous cycle. Quantitative immunocytochemistry was performed on MAb-labeled thin sections of Lowicryl-embedded ampullary region of hamster oviducts. Control experiments were also carried out to assess the specificity of the immunolabeling.

RESULTS

Quantitative analysis of the immunogold labeling indicated that maximum labeling for oviductin in the secretory granules of oviductal epithelial secretory cells was found around the time of ovulation, i.e., at estrus. The intensity of immunolabeling decreased from metestrus to diestrus 1, was at a minimum at diestrus 2, and started to increase at proestrus.

CONCLUSION

Together, these quantitative results indicate that expression of oviductin in the secretory granules of the hamster oviductal secretory cells is stage specific. Maximum labeling for the antigen coincides with the time of ovulation suggesting an important role for the oviductal epithelium in contributing its secretory product to the zona pellucida of oocytes freshly released from the ovary. Since the oviduct is the site of sperm-egg interaction and where fertilization and early embryo development take place, the maximal production of oviductin at the time of ovulation may facilitate some of these crucial steps during the intricate process of reproduction.