Secretory products of bovine oviductal epithelial cells support the viability and motility of bovine spermatozoa in culture in vitro

The bovine uterine fluid proteome is more impacted by the stage of the estrous cycle than the proximity of the ovulating ovary in the periconception period

Uterine secretions provide a suitable environment for sperm selective migration during a couple of days preceding ovulation and for early embryo development before implantation. Our goal was to identify and quantify proteins in the bovine uterine fluid during the periovulatory period of the estrous cycle. Genital tracts with normal morphology were collected from adult cyclic Bos taurus females in a local slaughterhouse and classified into pre-ovulatory or post-ovulatory stages of cycle (around days 19-21 and 0-5 of cycle, respectively; n = 8 cows per stage) based on ovarian morphology. Proteins from uterine fluid collected from the utero-tubal junction to the base of each horn (four pools of two cows per condition) were analyzed by nanoLiquid Chromatography coupled with tandem Mass Spectrometry (nanoLC-MS/MS). A total of 1214 proteins were identified, of which 91% were shared between all conditions. Overall, 57% of proteins were predicted to be secreted and 17% were previously reported in uterine extracellular vesicles. Paired comparisons between uterine horns ipsilateral and contralateral to ovulation evidenced 12 differentially abundant proteins, including five at pre-ovulatory stage. Furthermore, 35 proteins differed in abundance between pre- and post-ovulatory stages, including 21 in the ipsilateral side of ovulation. Functional analysis of identified proteins demonstrated roles in binding, metabolism, cellular detoxification and the immune response. This study provides a valuable database of uterine proteins for functional studies on sperm physiology and early embryo development.

Sperm migration, selection, survival, and fertilizing ability in the mammalian oviduct†

In vitro fertilization (IVF) gives rise to embryos in a number of mammalian species and is currently widely used for assisted reproduction in humans and for genetic purposes in cattle. However, the rate of polyspermy is generally higher in vitro than in vivo and IVF remains ineffective in some domestic species like pigs and horses, highlighting the importance of the female reproductive tract for gamete quality and fertilization. In this review, the way the female environment modulates sperm selective migration, survival, and acquisition of fertilizing ability in the oviduct is being considered under six aspects: (1) the utero-tubal junction that selects a sperm sub-population entering the oviduct; (2) the presence of sperm binding sites on luminal epithelial cells in the oviduct, which prolong sperm viability and plays a role in limiting polyspermic fertilization; (3) the contractions of the oviduct, which promote sperm migration toward the site of fertilization in the ampulla; (4) the regions of the oviduct, which play different roles in regulating sperm physiology and interactions with oviduct epithelial cells; (5) the time of ovulation, and (6) the steroid hormonal environment which regulates sperm release from the luminal epithelial cells and facilitates capacitation in a finely orchestrated manner.

Sperm interactions with the female reproductive tract: A key for successful fertilization in mammals

Sperm migration through the female genital tract is not a quiet journey. Uterine contractions quickly operate a drastic selection, leading to a very restrictive number of sperm reaching the top of uterine horns and finally, provided the presence of key molecules on sperm, the oviduct, where fertilization takes place. During hours and sometimes days before fertilization, subpopulations of spermatozoa interact with dynamic and region-specific maternal components, including soluble proteins, extracellular vesicles and epithelial cells lining the lumen of the female tract. Interactions with uterine and oviductal cells play important roles for sperm survival as they modulate the maternal immune response and allow a transient storage before ovulation. The body of work reported here highlights the importance of sperm interactions with proteins originated from both the uterine and oviductal fluids, as well as hormonal signals around the time of ovulation for sperm acquisition of fertilizing competence.

Identification by proteomics of oviductal sperm-interacting proteins

The interactions between oviductal fluid (OF) proteins and spermatozoa play major roles in sperm selection, storage and capacitation before fertilization. However, only a few sperm-interacting proteins in the OF has been identified and very little is known about the regulation of sperm-oviduct interactions across the estrous cycle. Samples of bovine frozen-thawed sperm from three bulls were incubated with OF at pre-, post-ovulatory stages (Pre-/Post-ov) or luteal phase (LP) of the estrous cycle (7 mg/mL proteins, treated groups) or with a protein-free media (control). The proteomes of sperm cells were assessed by nanoLC-MS/MS and quantified by label-free methods. A total of 27 sperm-interacting proteins originating in the OF were identified. Among those, 14 were detected at all stages, eight at Post-ov and LP and five only at LP. The sperm-interacting proteins detected at all stages or at LP and Post-ov were on average more abundant at LP than at other stages (P < 0.05). At Pre-ov, OVGP1 was the most abundant sperm-interacting protein while at Post-ov, ACTB, HSP27, MYH9, MYH14 and OVGP1 were predominant. Different patterns of abundance of sperm-interacting proteins related to the stage were evidenced, which greatly differed from those previously reported in the bovine OF. In conclusion, this study highlights the important regulations of sperm-oviduct interactions across the estrous cycle and provides new protein candidates that may modulate sperm functions.

Timing of oviductal fluid collection, steroid concentrations, and sperm preservation method affect porcine in vitro fertilization efficiency

OBJECTIVE

To determine optimal conditions for the inclusion of oviductal fluid (OF) in IVF protocols.

DESIGN

Experimental prospective study.

SETTING

Mammalian reproduction research laboratory.

ANIMAL(S)

Oviducts and ovaries from porcine females were collected at a slaughterhouse. A total of 30 oviducts and 1,285 oocytes were used. Boar-ejaculated spermatozoa were also used.

INTERVENTION(S)

In vitro-matured porcine oocytes were preincubated with OF collected from animals before or after ovulation and later fertilized in vitro. Zona pellucida digestion time in oocytes after preincubation in OF was assessed. Concentrations of E2 and P4 in OF were measured. IVF was performed, including within the culture media the E2 and P4 concentrations found in the preovulatory OF. The effect of preovulatory OF on IVF efficiency was compared between fresh and frozen-thawed spermatozoa.

MAIN OUTCOME MEASURE(S)

E2 and P4 concentrations in OF; penetration and monospermy rates; number of spermatozoa within the ooplasm and on the zona pellucida after IVF under different experimental conditions; zona pellucida resistance to protease digestion.

RESULT(S)

Preincubation of oocytes in OF collected before ovulation enhances IVF efficiency in the pig compared with OF collected after ovulation (29.58 ± 3.84 vs. 11.03 ± 2.69). When frozen-thawed spermatozoa are used for the IVF of these OF-treated oocytes, their fertilization ability increases compared with fresh semen. OF collected before and after ovulation shows significantly different concentrations of E2 (99.00 ± 8.72 vs. <10 pg/mL) and P4 (2.53 ± 0.66 vs. 12.27 ± 2.33 ng/mL), respectively. Addition of E2 and P4 at concentrations similar to those in the OF before ovulation partially simulates the effect of the fluid on IVF outcome.

CONCLUSION(S)

Preincubation of oocytes in OF collected before ovulation is a suitable protocol for increasing the efficiency of IVF with fresh semen in the pig model and could be a useful tool to increase the fertilization ability of frozen-thawed spermatozoa in other species. E2 concentrations in preovulatory OF are higher than those reported in blood serum at the same phase of the estrous cycle.

Bovine oviductal monolayers cultured under three-dimension conditions secrete factors able to release spermatozoa adhering to the tubal reservoir in vitro

Different in vitro models have been developed to understand the interaction of gametes and embryos with the maternal reproductive tract. We recently showed that bovine oviductal monolayers three-dimensionally cultured in Gray's medium on collagen-coated microporous polycarbonate inserts under liquid-air interface conditions are well polarized, develop cilia, remain viable for at least 3 weeks postconfluence, and mantain the viability of bound spermatozoa significantly better than bidimensionally cultured monolayers. Herein, we used these culture conditions to understand whether: (1) spermatozoa adhering to three-dimensionally cultured oviductal monolayers can be released by heparin or penicillamine as previously shown with bidimensionally cultured oviductal monolayers and explants; and (2) media conditioned by three-dimensionally cultured oviductal monolayers were able to release spermatozoa adhering to oviductal explants. Findings demonstrated that (1) spermatozoa adhering to three-dimensionally cultured oviductal monolayers are readily released by heparin and penicillamine, (2) media conditioned by three-dimensionally cultured oviductal monolayers are able to release spermatozoa bound to oviductal explants, (3) do not depress sperm motility and viability, (4) they improve sperm kinetics, and (5) promote binding to the zona pellucida. In conclusion, in vitro data suggest that the release of spermatozoa adhering to the oviductal reservoir in vivo can be triggered by factors secreted by the oviduct itself that induce sperm capacitation.

Bovine oviductal epithelial cells: their cell culture and applications in studies for reproductive biology

Epithelial cells of the mammalian oviduct play an important role in reproductive and developmental events that occur there. Oviductal epithelial cells from several mammalian species can be isolated and cultured in serum or serum-free medium in vitro and cell culture of bovine oviductal epithelial cells (BOEC) has been described by many investigators. Cultured BOEC show a wide variety of secretory activities and these secretory factors may influence early embryonic development or sperm function. Monolayer cultures of BOEC have been widely used for in vitro co-culture of bovine preimplantation embryos. The use of BOEC co-culture systems has improved embryonic development in nearly all the studies conducted. In addition, interaction of bovine spermatozoa with BOEC, in a similar manner to that observed for spermatozoa in vivo, induced specific changes in sperm capacitation and consequently improved the fertilizing capacity of bovine spermatozoa in vitro. Thus co-culture systems with BOEC may not only offer an excellent model for studying the mechanisms of capacitation and acrosome reaction of bovine spermatozoa but also provide a useful tool for the improvement of embryo development in vitro.

Regional and Cyclic Variations in the Ultrastructural Features of Secretory Cells in the Oviductal Epithelium of the Chinese Meishan Pig

The Chinese Meishan pig is prolific breed and it is considered that this pig has a capacity with higher rates of embryonic survival. The oviductal secretory cells may affect the embryonic development and survival. The aim of the present study was to investigate the ultrastructural features of secretory cells in the various regions of the Chinese Meishan pig oviduct during the follicular and luteal phases of the oestrous cycle. In the ampullar secretory cells, numerous secretory granules with moderately electron-dense matrices were present in the supranuclear cytoplasm and exocytosis of secretory granules was observed. The number of secretory granules was dramatically reduced in the ampullar secretory cells in the luteal phase. During the follicular phase in the fimbrial epithelium, the secretory cells contained rough endoplasmic reticulum and Golgi apparatus, but most cells had few small granules. In the luteal phase, the secretory cells in the ampullar and fimbrial epithelia extended beyond the luminal border of the ciliated cells. In the isthmus, many granules were present in the cytoplasm of secretory cells throughout the oestrous cycle, but the number of secretory granules was reduced in the luteal phase. The cytomorphometric data revealed that the height of ciliated cells decreased substantially in the fimbriae and ampulla at the luteal phase, while that of non-ciliated cells was less affected. These results suggest that the drastic reduction of cell height of ciliated cells cause the extrusion of most secretory cells beyond the ciliated cells in the fimbriae and ampulla during the luteal phase. In summary, our ultrastructural observations of Chinese Meishan pig oviduct revealed marked cyclic changes in the ultrastructural features of secretory cells. In particular, the ultrastructural features and the numbers of secretory granules were distinctive for each particular segment. These findings should provide insight into the regional and cellular differences in functions of secretory cells of the Chinese Meishan pig oviduct.

Bovine Seminal Plasma Proteins PDC-109, BSP-A3, and BSP-30-kDa Share Functional Roles in Storing Sperm in the Oviduct1

On ejaculation, sperm become coated with proteins secreted by the male accessory sex glands. In the bull, these proteins consist predominantly of the bovine seminal plasma family of proteins (BSPs): PDC-109 (BSP-A1/-A2), BSP-A3, and BSP-30-kDa. PDC-109 plays a role in forming an oviductal sperm reservoir by enabling sperm to bind to oviductal epithelium. Because PDC-109 has high sequence identity with the other BSPs, we tested BSP-A3 and BSP-30-kDa for the capacity to bind sperm to oviductal epithelium. BSP-A3 and BSP-30-kDa each increased binding of epididymal sperm to epithelium and were as effective as PDC-109 in competitively inhibiting binding of ejaculated sperm. Because binding extends the motile life of sperm, BSPs were tested for the ability to maintain sperm motility. BSP-treated epididymal sperm incubated with plasma membrane vesicles from bovine oviductal epithelium maintained progressive motility longer than untreated sperm. To our knowledge, this is the first report of this protective effect of BSPs. Similarities in function among the BSPs were reflected in their three-dimensional structure, whereas surface maps of electrostatic potential indicated differences in binding affinities and kinetics. Such differences may provide sperm with greater adaptability to variations among females. Altogether, these results indicate that BSPs play a crucial role in fertilization by maintaining sperm motility during storage.

In vivo versus in vitro fertilization

The complex sequence of biological steps involved in reproduction in vivo is only partially reproduced in current IVF procedures. In fact, events playing a key role in vivo such as male gamete selection can only be partially mimicked in vitro. To understand the role played by the mammalian oviduct in sperm storage and selection several in vitro sperm-oviductal cell co-culture systems have been developed. Particular sperm subpopulations have been reported to be selected by in vitro cultured oviductal cells through cell-cell adhesion, in different species. In the bovine, in vitro selected sperm have been demonstrated to be endowed with a superior zona pellucida binding and fertilization competence. In conclusion, research on in vitro sperm oviduct interaction may provide new basic information about early reproductive events allowing the development of alternative methods for a more physiological sperm selection in assisted reproductive biotechnologies.

Characterization of newly established clonal oviductal cell lines and differential hormonal regulation of gene expression

Oviductal functions have been studied mainly in primary epithelial cell culture and organ culture. However, secretory cells and ciliated cells coexist in the epithelium, and the small size of the oviduct limits the sources of both epithelial and stromal cells. To circumvent the limits, we attempted to establish clonal cell lines from an oviduct of a p53-deficient mouse. An oviduct was enzymatically digested and cultured in medium containing 10% fetal calf serum supplemented with estradiol-17beta. Morphologically distinct clones (10 epithelial and 4 fibroblastic clones) were established, and all clones expressed estrogen receptor alpha and progesterone receptor. Expression of a mouse oviduct-specific glycoprotein gene as a marker of secretory cells was limited in one clone and was stimulated by estrogens and suppressed by progesterone. Expression of helix factor hepatocyte nuclear factor/forkhead homologue-4 gene as a marker of ciliated cells was limited in two clones and was suppressed by estrogens. The two genes were never coexpressed in any clones. The results strongly suggest that the oviductal epithelium consists of two functionally determined populations. To our knowledge, this is the first establishment of functional clonal cell lines of the oviduct and makes it possible to study independently two oviductal functions, secretion and ciliogenesis.

Localization of the chaperone proteins GRP78 and HSP60 on the luminal surface of bovine oviduct epithelial cells and their association with spermatozoa

Upon their transit through the female genital tract, bovine spermatozoa bind to oviduct epithelial cells, where they are maintained alive for long periods of time until fertilization. Although carbohydrate components of the oviduct epithelial cell membrane are involved in these sperm/oviduct interactions, no protein candidate has been identified to play this role. To identify the oviduct factors involved in their survival, sperm cells were preincubated for 30 min with apical membranes isolated from oviduct epithelial cells, washed extensively, and further incubated for up to 12 h in the absence of apical membranes. During this incubation, sperm viability, motility, and acrosomal integrity were improved compared with cells preincubated in the absence of apical membranes. This suggests that, during the 30-min preincubation with apical membrane extracts, either an oviductal factor triggered intracellular events resulting in positive effects on spermatozoa or that such a factor strongly attached to sperm cells to promote a positive action. Similarly, spermatozoa were incubated with apical membranes isolated from oviduct epithelial cells labeled with [35S]-methionine and, upon extensive washes, proteins were separated by two-dimensional (2-D) gel electrophoresis to identify the factors suspected to have beneficial effects on spermatozoa. The six major proteins, according to their signal intensity on the autoradiographic film, were extracted from a 2-D gel of oviduct epithelial cell proteins run in parallel and processed for N-terminal sequencing of the first 15 amino acids. Of these, one was identical to heat shock protein 60 (HSP60) and one to the glucose-regulated protein 78 (GRP78). Their identities and association with spermatozoa were confirmed using an antibody directed against these proteins. This paper reports the localization of both GRP78 and HSP60 on the luminal/apical surface of oviduct epithelial cells, their binding to spermatozoa, and the presence of endogenous HSP60 in the sperm midpiece.

Effect of leukaemia inhibitory factor on long-term sperm motility and survival

Leukaemia inhibitory factor (LIF) is expressed at high constitutive levels in the human Fallopian tubal epithelium. In this study, the effect of human recombinant LIF on sperm motility and survival in vitro was investigated. Human spermatozoa were incubated in sperm washing medium that contained various concentrations of LIF at 37 degrees C and under 5% of CO(2) in air for up to 48 h. Sperm motion characteristics were measured using a sperm motility analyser. Sperm survival was determined by the hypo-osmotic swelling test. The effect of LIF on sperm motility was concentration-dependent and maximal effect was observed at a concentration of 5 ng/ml. Sperm motility was significantly higher after 24 h exposure to LIF compared with control (P < 0.001). Sperm survival was also prolonged in a concentration-dependent manner. LIF significantly enhanced sperm survival at higher concentrations (10 ng/ml) and the result was significant after 48 h exposure (P < 0.05). LIF increased long-term sperm motility and survival in vitro.

Effect of Bovine Oviduct Epithelial Cell Apical Plasma Membranes on Sperm Function Assessed by a Novel Flow Cytometric Approach1

In the bovine, as in many mammalian species, sperm are temporarily stored in the oviduct before fertilization by binding to the oviduct epithelial cell apical plasma membranes. As the oviduct is able to maintain motility and viability of sperm and modulate capacitation, we propose that proteins present on the apical plasma membrane of oviduct epithelial cells contribute to these effects. To verify this hypothesis, the motility of frozen-thawed sperm was determined after incubation for 6 h with purified apical plasma membranes from fresh or cultured oviduct epithelial cells or from bovine mammary gland cells as a control. Analysis of intracellular calcium levels was performed by flow cytometry on sperm incubated with fresh membranes using Indo-1 to assess the membrane effect on intracellular calcium concentration. The coculture of sperm with fresh and cultured apical membranes maintained initial motility for 6 h (65% and 84%, respectively). This effect was significantly different from control sperm incubated without oviduct epithelial cell apical membranes (23%), with mammary gland cell apical membranes (23%), or with boiled epithelial cell apical membranes (21%). Apical membranes from oviduct epithelial cells diminished the percentage of sperm that reached a lethal calcium concentration over a 4-h period (18.7%) compared with the control (53.8%) and maintained lower intracellular calcium levels in viable sperm. These results show that the apical plasma membrane of bovine oviduct epithelial cells contains anchored proteinic factors that contribute to maintaining motility and viability and possibly to modulating capacitation of bovine sperm.

Sulfated glycoconjugates are powerful modulators of bovine sperm adhesion and release from the oviductal epithelium in vitro

The mechanisms of sperm adhesion and release within the mammalian oviduct are still poorly understood. In this in vitro study, a previously developed adhesion assay was used to analyze the effects of heparin, N-desulfated heparin, fucoidan, dextran sulfate, and dextran on bovine sperm-oviductal cell adhesion and release. Results showed that 1) all sulfated glycoconjugates were powerful inhibitors of sperm binding to oviductal monolayers in a dose-dependent manner, whereas N-desulfated heparin and dextran had no effect; 2) sperm pretreatment with heparin and fucoidan markedly inhibited adhesion; 3) treatment of oviductal monolayers with heparinase I, II, or sodium chlorate (an inhibitor of sulfation) had no effect on sperm adhesion; 4) sulfated glycoconjugates were also powerful and quick inducers of sperm release from oviductal monolayers; and 5) addition of sulfated glycoconjugates to the cocultures caused a sudden increase of bound-sperm flagellar beat frequencies, followed by a release of highly motile sperm. In conclusion, these data support the hypothesis that sulfated glycoconjugates may act as signals that induce sperm release and migration from the oviductal reservoir.

Epithelial and stromal uterine cells cultured in vitro protect bovine sperm from hydrogen peroxide

It is known that large amounts of leukocytes colonize the uterus, and that these leukocytes can produce considerable quantities of hydrogen peroxide (H2O2) and other reactive oxygen species that are toxic to sperm. It has been shown recently that oviductal fluid has a catalase that helps to maintain sperm motility. Therefore, the current experiment was performed to determine if a similar mechanism of protection exists against peroxides within uterine cells. Sperm motility and velocity were recorded after a 6h incubation in 1) conditioned media in the presence of endometrial cells, 2) conditioned media without endometrial cells, 3) control media (48h without cells) over endometrial cells, or 4) control media alone. All these treatments were performed in the presence or absence of added catalase. Conditioned media, endometrial cells and catalase had a significant positive effect on the maintenance of sperm motility and velocity. Addition of anti-catalase antibodies did not neutralize the beneficial effect of the conditioned media. However, the concentrations of aromatic amino acids, known substrates for sperm amino acid oxidase, were significantly lower in uterine conditioned media as compared to control medium. This reduction of aromatic amino acids was in correlation with reduced H2O2 production by sperm as estimated by chemiluminescence. These results suggest that epithelial and stromal uterine cells do not maintain sperm motility by secreting catalase in the conditioned media, but rather by reducing the levels of aromatic amino acids and thus of peroxides generated in the presence of spermatozoa.

In vitro-cultured bovine oviductal cells bind acrosome-intact sperm and retain this ability upon sperm release

The mammalian oviduct plays a key role in sperm storage, capacitation, and selection. Specific oviduct secretions and/or binding to oviductal cells are thought to be responsible for the extension of the fertile life span of sperm. In this in vitro study, a quantitative assay for sperm binding was developed to analyze the mechanisms of sperm-oviductal cell adhesion and release in the bovine species. Distribution and acrosomal status of sperm bound to in vitro-cultured ampullary and isthmic cell monolayers were followed until the time of sperm release by means of fluorescence labeling techniques. In order to understand whether release is due to surface changes of sperm or oviductal cells, double incubation experiments with unlabeled and Hoechst-labeled sperm have been performed. Main findings demonstrate that (1) only acrosome-intact sperm bind specific bovine oviductal epithelial cells; (2) acrosomes of bound sperm are preserved intact over time; and (3) release of unreacted sperm is likely to be due to changes of the sperm surface, probably triggered by capacitation. These findings support the hypothesis that binding to oviductal cells is essential for preserving the sperm fertilization competence during the interval from the onset of estrus to ovulation.

Human oviductal cells produce a factor(s) that maintains the motility of human spermatozoa in vitro

OBJECTIVE

To characterize in part the factor(s) in conditioned medium (CM) that maintains sperm motility after human oviductal cell culture.

DESIGN

Controlled, experimental, laboratory study.

SETTING

University-based gynecology unit.

PATIENT(S)

Fallopian tubes were obtained from patients who underwent tubal ligation or hysterectomy. Semen with normal sperm parameters was obtained from men who visited subfertility clinics.

INTERVENTION(S)

Spermatozoa were incubated with CM and their motility was evaluated by a computer-aided sperm analysis system.

MAIN OUTCOME MEASURE(S)

Curvilinear velocity, straight-line velocity, average path velocity, linearity, amplitude of lateral head displacement, beat cross-frequency, and percentage of spermatozoa that exhibited hyperactivation.

RESULT(S)

Compared with their baseline motility (0 hour), spermatozoa incubated with CM maintained various motility parameters for a longer period than did control spermatozoa. All the motility parameters of the CM-treated spermatozoa were higher than those of the control spermatozoa at the same time point. This effect of CM was dose-dependent and increased with the duration of incubation. The effect was stable at 56 degrees C but was not observed after 100 degrees C heat treatment. Trypsin, but not proteinase K, abolished the effect. A fraction with a molecular weight of <3 kd in the CM was responsible for the observed effect.

CONCLUSION(S)

Human oviductal cells produce a peptide(s) that maintains sperm motility.

Effects of 17beta-oestradiol or oestrous stage-specific cow serum on the ability of bovine oviductal epithelial cell monolayers to prolong the viability of bull spermatozoa

The effect of 17beta-oestradiol and oestrous stage-specific cow serum on bovine oviductal epithelial cell monolayers to extend the viability of co-cultured bull spermatozoa was examined. Monolayers of cells from ampullary and isthmic segments were pre-treated with medium containing either oestrous cow serum, luteal-phase cow serum, 1 microg/ml 17beta-oestradiol + foetal bovine serum or foetal bovine serum alone (control) before the addition of motile frozen/thawed spermatozoa. Motility was visually assessed throughout a 48 h co-incubation period, while fertilising ability of spermatozoa was evaluated by adding in vitro matured bovine oocytes. Pre-treatment with 17beta-oestradiol or oestrous cow serum resulted in a higher percentage of motile spermatozoa after 18 h in isthmic and after 36 h in ampullary cultures compared with the control, but pre-treatment did not affect fertilisation rates. Only at 42 h in ampullary cultures was motility higher in luteal serum pre-treated cultures compared to the control. Motility was also assessed in medium conditioned by pre-treated monolayers. Pre-treatment with 17beta-oestradiol enhanced the ability of conditioned medium to prolong motility and medium conditioned with oestrous cow serum was superior to medium conditioned by luteal-phase serum at maintaining motility. In conclusion, the ability of oviductal epithelium to prolong the motility of spermatozoa is enhanced by 17beta-oestradiol.

Effects of bovine oviductal proteins on bull spermatozoal function

The effects of bovine oviductal proteins on bull sperm viability, acrosome reaction and motility were studied. Motile frozen/thawed spermatozoa from Percoll gradients were incubated with 1.0 mg/mL oviductal proteins (>8 kDa) extracted by ammonium sulphate precipitation from oviductal extract (OE) or serum-free oviductal epithelial cell-conditioned media (CM), treated in the presence (CM+) or absence (CM-) of 1 microg/mL 17beta-estradiol. Inclusion of oviductal proteins had a significant beneficial effect on sperm viability (76.3 to 80.6%+/-5.3) compared with the control (without oviductal proteins; 57.8%+/-5.3) immediately after the commencement of incubation. After 5 h, viability was significantly higher for CM- and OE treatments than for the control, although no differences were observed at 24 h. Acrosomal status only differed among treatments after 24 h, when higher percentages of acrosome- reacted spermatozoa were found in the control (46.0%+/-2.5) than in the oviductal protein treatments (33.1 to 38.2%+/-2.5). No differences in percentages of motile spermatozoa occurred within the first hour of incubation, although inclusion of CM proteins decreased sperm velocities, beat cross frequency, linearity, and straightness but increased values for mean angular displacement. These findings suggest that proteins secreted by oviductal epithelium promote viability, delay the acrosome reaction and suppress the motion of spermatozoa.

Sperm interaction with fallopian tube apical membrane enhances sperm motility and delays capacitation

OBJECTIVE

To understand the effect of sperm contact with the apical plasma membrane of tubal epithelial cells on sperm motility, velocity, and capacitation.

DESIGN

Prospective, controlled in vitro study.

SETTING

University medical center.

PATIENT(S)

Women of reproductive age undergoing hysterectomy for benign gynecologic indications and normozoospermic donors of proved fertility.

MAIN OUTCOME MEASURE(S)

Sperm motility as measured manually, velocity as measured by computer-assisted sperm motility analysis, and capacitation status as measured by the chlortetracycline fluorescence assay.

RESULT(S)

Sperm incubated with apical membrane vesicles had a significantly higher motility at 12 (87.4% +/- 3.4% versus 69.2% +/- 4.8% [mean +/- SEM]), 24 (85.2% +/- 3.1% versus 60.5% +/- 7.2%) and 48 hours (78.9% +/- 5.3% versus 42.4% +/- 11.3%) compared with control (sperm incubated with human tubal fluid media in the absence of apical membrane vesicles) (n = 4). Progressive velocity was significantly higher at 12 (78.2 +/- 1.4 versus 61.7 +/- 16.1 microns/s) and 24 (66.2 +/- 3.9 versus 34.4 +/- 9.8 microns/s) hours (n = 4). Incubation with apical membrane vesicles significantly slowed the transition from uncapacitated to capacitated chlortetracycline fluorescence pattern (n = 5).

CONCLUSION(S)

Contact with the apical plasma membrane of tubal epithelial cells enhances sperm motility and delays sperm capacitation in vitro.

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.