Observations by scanning electron microscopy of oviductal epithelial cells from cows at follicular and luteal phases

Cystic ovary disease (COD) alters structure and function of the bovine oviduct

Cystic ovary disease (COD) is a common cause of subfertility in dairy cattle. Therefore, the aim of this study was to provide novel concepts for cyst classification and to investigate the effects of COD on tubal microarchitecture, oviductal metabolic function, and the formation of the sperm reservoir. Bovine Fallopian tubes affected by follicular cysts, follicular cysts with luteinization and luteal cysts were investigated by a variety of microscopic and histological techniques and compared to control cows in metestrus and diestrus. We defined three types of cysts involved in COD, each of which had a characteristic wall thickness, inner wall appearance and cellular pattern within the cyst aspirate. Regarding the Fallopian tube, each cyst type was associated with a characteristic morphology, specifically the microarchitecture of the folds in ampulla, epithelial cell ratios, and ciliated/secretory cell size and form. Furthermore, each cyst type showed different patterns of tubal glycoprotein and acidic mucopolysaccharide synthesis, which was highly variable as compared to the controls. Our studies are the first to characterize the effects of COD on the Fallopian tube, which promotes the establishment of novel, cyst-specific therapeutic concepts in cattle and helps gain a holistic view of the causes of subfertility in cows with COD.

Immunohistochemical identification of epithelial cell types in the isthmus of bovine oviduct: Comparison with the ampulla

The oviductal epithelium consists of ciliated and non-ciliated cells, and their numbers vary depending on the segment of the oviduct and stage of the estrous cycle. Compared with the ampulla, fewer cyclic changes in the number of the two types of cells occur in the isthmus. Recently, we have reported that the epithelium in the ampullary oviduct is composed of many types of cells during different translational/transcriptional states, and their numbers change during the estrous cycle. However, detailed information regarding the epithelial cell subtypes lining the isthmic oviductal epithelium has not yet been reported. In this study, we aimed to identify the epithelial subtypes in the isthmus of the oviduct using immunohistochemistry. Some similarities and differences were observed between the ampulla and isthmus. As observed in the ampulla, epithelial cells of the isthmus expressed either FOXJ1 (ciliogenesis marker) or PAX8 (non-ciliated cell marker). The estrous cycle affected the number of Ki67⁺ cells but not that of ciliated cells. A relatively high rate of Ki67⁺ cells (60%) was observed at 1-4 days after the ovulation. Interestingly, unlike the ampulla, Ki67⁺/FOXJ1⁺ cells (12.6 ± 1.1%) were discovered in the isthmus. Double staining for Ki67 with FOXJ1, PAX8, or Centrin-1 (a centriole marker) revealed that Centrin-1 was localized on the apical surface of some Ki67⁺/FOXJ1⁺ cells. In conclusion, some epithelial cell subtypes exist in the isthmus of the oviduct and isthmus-specific cell subtypes have been identified. These region-specific cells may provide functional and morphological differences between the ampulla and isthmus of the oviduct.

Characterization of circular RNA profiles of oviduct reveal the potential mechanism in prolificacy trait of goat in the estrus cycle

The mammalian oviduct is functionally highly diverse during the estrus cycle. It provides a suitable milieu for oocyte maturation, sperm capacitation, fertilization, early embryo development and transportation. While there have been many studies of molecular mechanisms on the kidding number of goats, a systematic analysis by which the underlying circular RNAs (circRNAs) changes in the oviduct related to prolificacy traits is lacking. Herein, we present a comprehensive circRNA atlas of the oviduct among high- and low-fecundity goats in the follicular phase (FH vs. FL), luteal phase (LH vs. LL), and estrus cycle (FH vs. LH; FL vs. LL) to unravel their potential regulatory mechanisms in improving kidding number. We generated RNA sequencing data, and identified 4,078 circRNAs from twenty sampled Yunshang black goats. Many of these circRNAs are exon-derived and differentially expressed between each comparison group. Subsequently, eight differentially expressed (DE) circRNAs were validated by RT‒qPCR, which was consistent with the RNA-seq data. GO and KEGG enrichment analyses suggested that numerous host genes of DE circRNAs were involved in the hormone secretion, gamete production, fertilization, and embryo development processes. The competing endogenous RNA (ceRNA) interaction network analysis revealed that 2,673 circRNA–miRNA–mRNA axes (including 15 DE circRNAs, 14 miRNAs, and 1,699 mRNAs) were formed, and several target genes derived from the ceRNA network were associated with oviduct functions and reproduction, including SMAD1, BMPR1B, IGF1, REV1, and BMP2K. Furthermore, miR-15a-5p, miR-181b-5p, miR-23b-5p, miR-204-3p, and miR-145-5p might play important roles in reproduction. Finally, a novel circRNA, circIQCG, was identified as potentially involved in embryo development. Overall, our study provides a resource of circRNAs to understand the oviductal function and its connection to prolificacy trait of goats in the differentiation estrus cycle.

Prosaposin in the rat oviductal epithelial cells

Prosaposin (PSAP) has two forms: a precursor and a secreted form. The secreted form has neurotrophic, myelinotrophic, and myotrophic properties. The precursor form is a precursor protein of saposins A-D. Although the distribution of PSAP in male reproductive organs is well known, its distribution in female reproductive organs, especially in the oviduct, is unclear. Immunoblots and immunohistochemistry of oviducts showed that oviductal tissues contain PSAP proteins, and a significant increase in PSAP was observed in the estrus-metestrus phase compared to the diestrus-proestrus phase in the ampulla. To identify PSAP trafficking in cells, double-immunostaining was performed with antibodies against PSAP in combination with sortilin, mannose 6 phosphate receptor (M6PR), or low-density lipoprotein receptor-related protein 1 (LRP1). PSAP and sortilin double-positive reactions were observed near the nuclei, as well as in the apical portion of microvillous epithelial cells, whereas these reactions were only observed near the nuclei of ciliated epithelial cells. PSAP and M6PR double-positive reactions were observed near the nuclei of microvillous and ciliated epithelial cells. PSAP and M6PR double-positive reactions were also observed in the apical portion of microvillous epithelial cells. PSAP and LRP1 double-positive reactions were observed in the plasma membrane and apical portion of both microvillous and ciliated epithelial cells. Immunoelectron staining revealed PSAP immunoreactive small vesicles with exocytotic features at the apical portion of microvillous epithelial cells. These findings suggest that PSAP is present in the oviductal epithelium and has a pivotal role during pregnancy in providing an optimal environment for gametes and/or sperm in the ampulla.

Analysis of ciliogenesis process in the bovine oviduct based on immunohistochemical classification

The oviductal epithelium is composed of ciliated and non-ciliated cells. The proportions of these cells change during the estrous cycle. However, the mechanism underlying this cyclic change in the cell proportions remains unclear. Our previous study indicated that ciliated cells are derived from non-ciliated cells. Here, we aimed to investigate the mechanism regulating the changes in the populations of ciliated and non-ciliated cells during the estrous cycle. To this end, we examined the numbers of cells that were positive for acetylated-α-tubulin (cilia marker), Ki67 (proliferation marker), PAX8 (non-ciliated cell marker), and FOXJ1 and MYB (ciliogenesis markers) in the epithelial cells at four different estrous stages (Stage I: days 1-4 after ovulation, Stage II: days 5-10, Stage III: days 11-17, and Stage IV: days 18-20) by immunohistochemistry. The oviductal epithelial cells expressed either FOXJ1 or PAX8. All the acetylated-α-tubulin⁺ cells were positive for FOXJ1, although there were a few acetylated-α-tubulin^-/FOXJ1⁺ cells. MYB was expressed in both the FOXJ1⁺ and PAX8⁺ cells, but it was not expressed in the Ki67⁺ cells. The numbers of Ki67⁺ and MYB⁺ cells were the highest in Stage IV, while the numbers of FOXJ1⁺ and acetylated-α-tubulin⁺ cells were the highest in the following Stage I, suggesting that ciliogenesis is associated with the estrous cycle. Thus, based on immunological classification, the oviductal epithelium contains at least seven types of cells at different translational/transcriptional states, and their number is regulated by the estrous cycle. This cyclic event might provide an optimal environment for gamete transport, fertilization, and embryonic development.

Scanning electron microscopic study on the oviduct of buffalo during follicular and luteal phases of estrous cycle

The present investigation was conducted on different segments of oviduct of six buffaloes each during follicular and luteal phases of estrous cycle. The mucosa of different segments of oviduct was thrown into folds which were oriented as primary and secondary folds. The lamina epithelialis was lined with ciliated and non-ciliated cells. Ciliated cells had many kinocilia during the follicular phase. The non-ciliated cells were of two types, viz. secretory and non-secretory type. The infundibulum during the follicular phase had large number of ciliated cells as compared to that of luteal phase. The secretory cells had short, thick and stubby microvillous processes. The ampulla had almost similar ciliation as that of infundibulum. The luminal surface of secretory cells had secretory blebs and secretory material over it. The extent of ciliation decreased towards the uterotubal junction. The ciliated cells were more during the follicular phase as compared to that of the luteal phase.

Does migrative and proliferative capability of epithelial cells reflect cellular developmental competence?

Mammalian epithelial and epithelial-like cells are significantly involved in various processes associated with tissue development, differentiation and oncogenesis. Because of that, high number of research is focused on identifying cells that express stem-like or progenitor characteristics. Identifying such cells and recognizing their specific markers, would open new clinical opportunities in transplantology and oncology. There are several epithelia characterized by their ability to rapidly proliferate and/or differentiate. Due to their function or location they are subject to cyclic changes involving processes of apoptosis and regeneration. Literature presenting well-structured studies of these types of epithelia was analyzed in order to compare various results and establish if epithelial cells’ migrative and proliferative ability indicates their stemness potential. Endometrial, ovarian, oviductal and oral mucosal epithelia were analyzed with most of the publications delivering relatively unified results. The ability to rapidly proliferate/differentiate usually indicated the presence of some kind of stem/stem-like/progenitor cells. Most of the papers focused on pinpointing the exact location of these kind of cells, or analyzing specific markers that would be used for their future identification. There have also been substantial proportion of research that focused on discovering growth factors or intercellular signals that induced proliferation/differentiation in analyzed epithelia. Most of the research provided valuable insights into the modes of function and characteristics of the analyzed tissue, outlining the importance of such study for the possible clinical application of in vitro derived cell cultures.

Amino acids metabolism and degradation is regulated during porcine oviductal epithelial cells (OECs) primary culture in vitro – a signaling pathways activation approach

The ovary is part of the reproductive system, possessing very important functions in the reproduction process (ovum and embryo transfer, providing a suitable environment for sperm capacitation, etc.). There are two types of cells in the fallopian tubes: alveolar and secretive cells. These study shows the metabolic processes in pig oviductal epithelial cells associated with the activation of signaling pathways of amino acids metabolism and degradation during long-term in vitro culture. Oviductal epithelial cells from 45 colonies in the anestrous phase of the estrous cycle have been utilized in this study. RNA extract from the OEC primary cultures was pooled after 24h, 7days, 15 days and 30 days from the beginning of culture and the transcriptome investigated by Affymetrix® Porcine Gene 1.1 ST. From the whole transcript that consisted of 2009 different genes, 1537 were upregulated and 995 were downregulated after 7 days of culture, 1471 were upregulated and 1061 were downregulated after 15 days of culture and 1329 were upregulated and 1203 were downregulated after 30 days of culture. The results of these studies provide, for the first time, information on the activation of metabolic pathways of amino acids such as valine, leucine, isoleucine, cysteine, and methionine in the investigated tissue. They also indicate genes that may be OECs-specific genetic markers that are expressed or upregulated during long-term in vitro culture.

In Vivo Imaging of the Mouse Reproductive Organs, Embryo Transfer, and Oviduct Cilia Dynamics Using Optical Coherence Tomography

The oviduct (or fallopian tube) serves as the site where a number of major reproductive events occur for the start of a new life in mammals. Understanding the oviduct physiology is essential to uncover hidden mechanisms of the human reproduction and its disorders, yet the current analysis of the oviduct that is largely limited to in vitro imaging is a significant technical hurdle. To overcome this barrier, we have recently developed in vivo approaches based on optical coherence tomography for structural and functional imaging of the mouse oviduct. In this chapter, we describe the details of such live imaging methods that allow for three-dimensional visualization of the oviduct wall morphology, microscale mapping of the oviduct cilia beat frequency, and high-resolution observation of the cumulus-oocyte complex at the cellular level. We expect this set of imaging tools will enable novel studies toward a comprehensive knowledge of the mammalian reproduction.

Metabolite availability as a window to view the early embryo microenvironment in vivo

A preimplantation embryo exists independent of blood supply, and relies on energy sources from its in vivo environment (e.g., oviduct and uterine fluid) to sustain its development. The embryos can survive in this aqueous environment because it contains amino acids, proteins, lactate, pyruvate, oxygen, glucose, antioxidants, ions, growth factors, hormones, and phospholipids-albeit the concentration of each component varies by species, stage of the estrous cycle, and anatomical location. The dynamic nature of this environment sustains early development from the one-cell zygote to blastocyst, and is reciprocally influenced by the embryo at each embryonic stage. Focusing on embryo metabolism allowed us to identify how the local environment was deliberately selected to meet the dynamic needs of the preimplantation embryo, and helped reveal approaches to improve the in vitro culture of human embryos for improved implantation rates and pregnancy outcome.

Periovulatory follicular fluid levels of estradiol trigger inflammatory and DNA damage responses in oviduct epithelial cells

OBJECTIVE

Ovarian steroid hormones (mainly E2 and P4) regulate oviduct physiology. Serum-E2 acts on the oviduct epithelium from the basolateral cell compartment. Upon ovulation, the apical compartment of the oviduct epithelium is temporarily exposed to follicular fluid, which contains much higher levels of E2 than serum. The aim of this study was to evaluate the effects of human periovulatory follicular fluid levels of E2 on oviduct epithelial cells using two porcine in vitro models.

METHODS

A cell line derived from the porcine oviductal epithelium (CCLV-RIE270) was characterized (lineage markers, proliferation characteristics and transformation status). Primary porcine oviduct epithelial cells (POEC) were cultured in air-liquid interface and differentiation was assessed histologically. Both cultures were exposed to E2 (10 ng/ml and 200 ng/ml). Proliferation of CCLV-RIE270 and POEC was determined by real-time impedance monitoring and immunohistochemical detection of Ki67. Furthermore, marker gene expression for DNA damage response (DDR) and inflammation was quantified.

RESULTS

CCLV-RIE270 was not transformed and exhibited properties of secretory oviduct epithelial cells. Periovulatory follicular fluid levels of E2 (200 ng/ml) upregulated the expression of inflammatory genes in CCLV-RIE270 but not in POEC (except for IL8). Expression of DDR genes was elevated in both models. A significant increase in cell proliferation could not be detected in response to E2.

CONCLUSIONS

CCLV-RIE270 and POEC are complementary models to evaluate the consequences of oviduct exposure to follicular fluid components. Single administration of periovulatory follicular fluid E2 levels trigger inflammatory and DNA damage responses, but not proliferation in oviduct epithelial cells.

Remodeling of bovine oviductal epithelium by mitosis of secretory cells

Two types of oviductal epithelial cells, secretory and ciliated, play crucial roles in the first days after fertilization in mammals. Secretory cells produce various molecules promoting embryo development, while ciliated cells facilitate transport of oocytes and zygotes by ciliary beating. The proportions of the two cell types change during the estrous cycle. The proportion of ciliated cells on the oviductal luminal surface is abundant at the follicular phase, whereas the proportion of secretory cells gradually increases with the formation of the corpus luteum. In the present study, we hypothesize that the proportions of ciliated and secretory epithelial cells are regulated by mitosis. The proportion of the cells being positive for FOXJ1 (a ciliated cell marker) or Ki67 (a mitosis marker) in epithelial cells during the estrous cycle were immunohistochemically examined. Ki67 and FOXJ1 or PAX8 (a secretory cell marker), were double-stained to clarify which types of epithelial cells undergo mitosis. In the ampulla, the percentage of FOXJ1-positive cells was highest at the day of ovulation (Day 0) and decreased by about 50 % by Days 8-12, while in the isthmus it did not change during the estrous cycle. The proportion of Ki67-positive cells was highest at around the time of ovulation in both the ampulla and isthmus. All the Ki67-positive cells were PAX8-positive and FOXJ1-negative in both the ampulla and isthmus. These findings suggest that epithelial remodeling, which is regulated by differentiation and/or proliferation of secretory cells of the oviduct, provides the optimal environment for gamete transport, fertilization and embryonic development.

Steroid hormones in bovine oviductal fluid during the estrous cycle

Ovarian steroid hormones are major regulators of the physiology of the oviduct and reproductive events occurring within the oviduct. To establish a whole steroid profiling of the bovine oviductal fluid (OF) during the estrous cycle, contralateral and ipsilateral (to the corpus luteum or preovulatory follicle) oviducts were classified into four stages of the estrous cycle (n = 18-27 cows per stage): postovulatory (Post-ov), mid-luteal (Mid-lut), late luteal (Late-lut), and preovulatory on the basis of the ovarian morphology and intrafollicular steroid concentrations. Steroids were extracted from pools of 150 to 200 μL OF (three to 10 cows per pool; three to four pools per "stage × side" group), purified, fractioned by high-performance liquid chromatography, and analyzed by gas chromatography coupled with tandem mass spectrometry. The concentrations of progesterone (P4) in ipsilateral OF increased from Post-ov (56.9 ± 13.4 ng/mL) to Mid-lut (120.3 ± 34.3 ng/mL), then decreased from Late-lut (76.7 ± 1.8 ng/mL) to Pre-ov (6.3 ± 1.7 ng/mL), and were four to 16 times higher than in contralateral OF. Most P4 metabolites followed similar patterns of variation. Concentrations of 17beta-estradiol (E2) were significantly higher at Pre-ov (290.5 ± 63.2 pg/mL) compared with all other stages (<118.3 pg/mL), with no difference regarding the side of ovulation. Concentrations of androstenedione displayed a pattern similar to that of E2, whereas other androgens, estrone, and corticoids did not vary between stages or sides. In conclusion, a highly concentrated and fluctuating hormonal environment was evidenced in the bovine OF. These results could be useful to improve media for IVF, embryo development, and culture of oviductal cells.

Morphology and Aquaporin Immunohistochemistry of the Uterine Tube of Saanen Goats (Capra hircus): Comparison Throughout the Reproductive Cycle

The expression of six different aquaporins (AQP1, 2, 3, 4, 5 and 9), integral membrane water channels that facilitate bi-directional passive movement of water, was investigated by immunohistochemistry in the uterine tube of pre-pubertal and adult Saanen goats (Capra hircus), comparing the different phases of the oestrous cycle. Regional morphology and secretory processes were markedly different during the goat oestrous cycle. The tested AQP molecules showed different expression patterns in comparison with already studied species. AQP1-immunoreactivity was evidenced at the endothelium of blood vessels and in nerve fibres, regardless of the tubal tract and cycle period. AQP4-immunoreactivity was shown on the lateral plasmalemma in the basal third of the epithelial cells at infundibulum and ampulla level in the cycling goats, more evidently during follicular than during luteal phase. No AQP4-immunoreactivity was noticed at the level of the isthmus region, regardless of the cycle phase. AQP5-immunoreactivity, localized at the apical surface of epithelial cells, increased from pre-puberty to adulthood. Thereafter, AQP5-immunoreactivity was prominent during the follicular phase, when it strongly decorated the apical plasmalemma of all epithelial cells at ampullary level. During luteal phase, immunoreactivity was discontinuous, being weak to strong at the apex of the secretory cells protruding into the lumen. In the isthmus region, the strongest AQP5-immunoreactivity was seen during follicular phase, with a clear localization in the apical plasmalemma of all the epithelial cells and also on the lateral plasmalemma. AQP2, 3 and 9 were undetectable all along the goat uterine tube. Likely, a collaboration of different AQP molecules sustains the fluid production in the goat uterine tube. AQP1-mediated transudation from the blood capillaries, together with permeation of the epithelium by AQP4 in the basal rim of the epithelial cells and final intervening of apical AQP5, could be involved in fluid production as well as in secretory processes.

Scanning and transmission electron microscopic analysis of ampullary segment of oviduct during estrous cycle in caprines

The ampullary segment of the mammalian oviduct provides suitable milieu for fertilization and development of zygote before implantation into uterus. It is, therefore, in the present study, the cyclic changes in the morphology of ampullary segment of goat oviduct were studied during follicular and luteal phases using scanning and transmission electron microscopy techniques. Topographical analysis revealed the presence of uniformly ciliated ampullary epithelia, concealing apical processes of non-ciliated cells along with bulbous secretory cells during follicular phase. The luteal phase was marked with decline in number of ciliated cells with increased occurrence of secretory cells. The ultrastructure analysis has demonstrated the presence of indented nuclear membrane, supranuclear cytoplasm, secretory granules, rough endoplasmic reticulum, large lipid droplets, apically located glycogen masses, oval shaped mitochondria in the secretory cells. The ciliated cells were characterized by the presence of elongated nuclei, abundant smooth endoplasmic reticulum, oval or spherical shaped mitochondria with crecentric cristae during follicular phase. However, in the luteal phase, secretory cells were possessing highly indented nucleus with diffused electron dense chromatin, hyaline nucleosol, increased number of lipid droplets. The ciliated cells had numerous fibrous granules and basal bodies. The parallel use of scanning and transmission electron microscopy techniques has enabled us to examine the cyclic and hormone dependent changes occurring in the topography and fine structure of epithelium of ampullary segment and its cells during different reproductive phases that will be great help in understanding major bottle neck that limits success rate in vitro fertilization and embryo transfer technology.

In vitro mimicking of estrous cycle stages in porcine oviduct epithelium cells: estradiol and progesterone regulate differentiation, gene expression, and cellular function

Throughout the estrous cycle the oviduct epithelium undergoes dramatic morphological and functional changes. To elucidate cyclic cellular events and associated regulation mechanisms of 17beta estradiol (E2) and progesterone (P4), we mimicked estrous cycle stages in vitro using a culture system of primary porcine oviduct epithelium cells (POEC). Cells were polarized in an air/liquid interface and then treated with E2 and P4 for physiological time periods: In experiment 1, high concentration of P4 with low concentration of E2 for 10 days resembled diestrus; in experiment 2, following the previous diestrus, sequential high E2 with low P4 for 2.5 days represented estrus. Histomorphometry and electron microscopy showed cyclic changes in cellular height, cell population, and cilia density under the influence of hormone stimulation. Transepithelial electrical resistance was high in simulated diestrus but reduced in estrus. Thus, E2 and P4 affect cellular polarity, transformation of ciliated and secretory cells, as well as electrical conductivity of oviduct epithelium. Simulation of diestrus led to significant decrease in expression of hormone receptors (PGR and ESR1) and other epithelial markers (MUC16, OVGP1, and HSP90B1), while sequential simulated estrus caused an increase in these markers. The hormonal regulation of some marker genes was clearly time-dependent. Furthermore, POEC showed increased sperm-binding capacity in simulated estrus. In this study, we also present a novel approach based on the AndroVision software, which can be routinely utilized as a parameter for ciliary activity, and for the first time, we showed fluid movement patterns along the epithelium lining in vitro.

Topographic and ultrastructural variations in isthmus segment of oviduct during oestrous cycle in Caprines

In the present study, the morphological variations in the isthmus segment of goat (Capra hircus) oviduct were studied using scanning and ultrastructural techniques during luteal and follicular phases of oestrous cycle. Topographic analysis of the isthmus epithelium in the follicular phase demonstrated irregular distribution of ciliated cells on the epithelium. A few secretory cells possessed bulbous apical processes which were concealed by the cilia. Cyclic changes were noticed in the secretory cells of isthmus. Under electron microscopy the isthmus region of the oviduct during the follicular phase revealed presence of almost blunt processes at their apical surfaces. The secretory cells were attached to the basal lamina and were characterized by the presence of secretory granules, numerous ribosomes, extensive smooth endoplasmic reticulum, well-developed golgi zones in the cytoplasm, and a microvillus luminal surface. The parallel use of these two methods in isthmus segment of the oviduct has enabled us to analyze the marked cyclic variations in the topography and fine structure during follicular and luteal phases of the oestrous cycle. The results of the present investigation on topography and ultrastructure will be of great help in explaining different bottlenecks of gamete interaction, maturation, fertilization, and early embryo development.

Surface alteration in aging of rat tubae uterinae epithelium

OBJECTIVE

Aim of the study was evaluating arrangement of apical surface differentiation in cross-sections of tuba uterinae in different age groups by scanning electron microscope.

MATERIAL AND METHODS

Six groups were created with 36 Wistar rat; 1(st) group: neonate (1(th) day) (n=6), 2(nd) group: young (22(nd) day) (n=6), 3(rd) group: prepubertal (4-6 week) (n=6), 4(th) group: adult (10 week) (n=6), 5(th) group: premenopausal (8 month) (n=6), 6(th) group: old (18-20 month) (n=6). Tissue samples examined with scanning electron microscope.

RESULTS

When surface differentiations of epithelial cells in tubae uterinae from birth to menopause were considered, it was determined that the cell with microvilli are first maturing cells and degenerated by ages first. It was observed that the ciliated cells are last maturing cells and subsisting as a mature cell during the postmenopausal period.

CONCLUSION

Towards the menopause degeneration in microvillous cells together with lack of secretion may affect sperm nutrition adversely. The increase of ciliated cells in aging may be a physiological result related to the active role of cilia movement in the sperm and early embryo transport against a probable decrease in muscle contraction in aging.

Ciliary activity in the oviduct of cycling, pregnant, and muscarinic receptor knockout mice

The transport of the oocyte and the embryo in the oviduct is managed by ciliary beating and muscular contractions. Because nonneuronally produced acetylcholine influences ciliary beating in the trachea via the muscarinic receptors M2 and M3, we supposed that components of the cholinergic system may also modulate ciliary activity in the oviduct. To address this issue, we analyzed the expression profile of muscarinic receptors (CHRMs) in the murine oviduct by RT-PCR and assessed ciliary beat frequency (CBF) and cilia-driven particle transport speed (PTS) on the mucosal surface of opened oviductal segments in correlation with histomorphological investigations. RT-PCR of laser-assisted microdissected epithelium revealed expression of Chrm subtypes Chrm1 and Chrm3. In opened isthmic segments, particle transport was barely seen, correlating with a significantly lower number of ciliated cells compared to the ampulla. In the ampulla, basal PTS and CBF were high (71 μm/sec and 21 Hz, respectively) both in cycling and pregnant wild-type mice and in mice with targeted deletion of the Chrm genes Chrm1, Chrm3, Chrm4, and Chrm5. In contrast to the trachea, where basal ciliary activity was low and largely enhanced by muscarinic stimulation, muscarinic agonists and antagonists did not affect the high ampullar PTS. Our results imply that this high oviductal autonomous ciliary activity is independent from the intrinsic cholinergic system and serves to maintain optimal clearance of the tube throughout all stages of the estrous cycle and early pregnancy.

Isolation and characterization of oviduct-specific glycoproteins from ampulla and isthmus parts of cyclic and acyclic buffalo for studying differential microenvironment

The present study characterized the glycoproteins synthesized by buffalo oviduct. Scanning electron microscopy analyses of the ampullary and isthmic segments of cyclic and acyclic buffaloes showed ultrastructural variations in ciliated and nonciliated cells. Mucosal proteins were extracted by scrapping of different segments of oviduct and, after centrifugation, the remainder tissues were subjected to establish primary cell culture system of oviduct epithelial cells and conditioned media were prepared. Time- and concentration-dependent effects of trypsinization on the establishment of primary monolayer culture showed that 0.25% trypsin for 1-2 min at 37 °C were the optimal conditions. Total protein content in oviductal tissues and conditioned media was quantified and analyzed by SDS-PAGE which showed marked variation in different segments of the oviduct. Western blot analysis revealed five major oviduct-specific glycoproteins (OGPs) in cyclic oviduct (ampulla and isthmus) with Mw 180, 95, 75, 66 and 35 kDa in the oviduct extract and two glycoproteins with Mw 95 and 66 kDa in conditioned media. However, in acyclic oviduct (ampulla and isthmus), three glycoproteins were immunostained with Mw 180, 95 and 66 kDa in the oviduct extract and one glycoprotein with Mw 66 kDa in conditioned media. Indirect Enzyme-Linked Immuno Sorbent Assay (ELISA) results showed significant differences of OGPs in different segments of cyclic and acyclic buffaloes and, thus, indicative of segmental variation in the synthesis and secretion of glycoproteins. Oviductal extract secretes more amounts of OGPs as compared to the conditioned medium. The role of these OGPs may be defined and exploited for influencing the fertilization process and/or subsequent embryonic development.

The morphological and functional observation of the gap junction proteins in the oviduct epithelia in young and adult hamsters

The histological morphology of oviduct epithelia have been described well, however, the expression pattern of the gap junction proteins in the cells, and the function related with the proteins, such as [Ca2+]i dynamics pattern of living oviduct epithelia at different ages have not been clarified. We used immunohistochemistry to compare the expression pattern of gap junction proteins in the cells of the young and adult groups. Moreover, we used real-time confocal microscopy to observe the spontaneous Ca2+ oscillation (spontaneous fluctuation) in freshly isolated epithelia (ciliated cells) in ampulla potion of oviduct from the two groups. The results show as demonstrated by immunohistochemistry the gap junction proteins (Cx26, Cx32 and Cx43) formed a well-regulated expression in the young animals, but not in the adult animals. In addition, the [Ca2+]i dynamics of ciliated cells in freshly oviduct epithelia have a spontaneous fluctuation pattern that occurs without any stimulation in the young animals, but this pattern was not observed in the adult animals. In conclusions, our findings suggest that gap junctions regulate the spontaneous fluctuation of [Ca2+]i dynamics in ciliated cells of oviduct epithelia in young animals.

Cyclic regulation of apoptotic gene expression in the mouse oviduct

The oviduct is a dynamic structure whose function relies upon cyclic changes in the morphology of both ciliated and secretory luminal epithelial cells. Unfortunately, infection of these epithelial cells by sexually transmitted pathogens can lead to pelvic inflammatory disease, ectopic pregnancies and infertility. The disruption of normal, cyclic apoptosis in the oviducal epithelium appears to be a causal factor of oviducal pathology and therefore, these pathways represent a potential target for diagnosis and therapeutic intervention. The objective of this study was to determine the pattern of expression for apoptotic genes in the oviduct of the naturally cycling mouse, generating fundamental information that can be applied to the development of animal models for research and the identification of targets for disease intervention. Whole oviducts were collected from regular cycling mice killed at 1p.m. on each day of the oestrous cycle and the expression of 84 apoptotic genes determined by targeted PCR super-array. Intact and cleaved caspases were then evaluated by western blotting. The expression of mRNA for genes classified as pro-apoptotic (Bad, Bak1 and Bok) and anti-apoptotic (Bag3, Bnip2 and Xiap) was regulated by day (P < 0.05). Differences in the temporal expression of several p53-related genes (Trp53bp2, Trp53inp1 and Trp73), those specific to the TNF superfamily (Tnfrsf10 and Tnfsf10b) and one caspase (Casp14) were also observed (P < 0.05). The cleaved forms of Caspases-3, -6 and -12 were all detected throughout the oestrous cycle. These results represent the first pathway-wide analysis of apoptotic gene expression in the murine oviduct.

Embryos and culture cells: a model for studying the effect of progesterone

A positive association between P4 concentration and initial bovine embryo survival has been reported. The objective of this study was to establish two coculture systems as a model to study the influence of progesterone on the initial bovine embryo development. Granulosa cells (GC) or bovine oviduct epithelial cells (BOECs) were used at the base of embryo culture medium microdroplets (TCM199 and 10% of superovulated oestrus cow serum, (SOCS)) supplemented or not with progesterone (P4, 33.4 ng mL(-1)) and/or a progesterone receptor antagonist (onapristone, OP, 2.2x10(-5)M). Presumptive zygotes were transferred to monolayers after in vitro maturation and fertilization of bovine oocytes with thawed swim-up selected sperm. Embryo development was carried out according to the following groups: experiment 1, BOEC (n=378) and BOEC plus OP (n=325); experiment 2, GC (n=514); GC plus OP (n=509); BOEC (n=490); BOEC plus P4 (n=500); BOEC plus P4 and OP (n=502). Embryos were checked for cleavage at day 2 and for stage development between days 8 and 12 of culture. In experiment 1, no differences (P>0.05) were identified between BOEC and BOECOP groups for embryo rates of development, quality or developmental stages. Also in experiment 2, no differences were found in embryo rates of development, quality or developmental stages between embryos cultured under the two coculture systems when no supplementation was added. Embryo development rates were not affected by OP presence in GCOP group. However, P4 negatively affected Day 8 (D8) embryo development rates in BOEC system (BOECP4=16.8+/-2.6% vs. BOEC=23.7+/-1.7%, P=0.02). This negative effect was abolished when P4 antagonist (OP) was added to the culture medium. BOEC supplementation with P4 also induced a delay on embryo development at D8 as confirmed by a lower development score (BOECP4=3.0+/-1.4 vs. GC=3.4+/-0.1, GCOP=3.5+/-0.1, BOEC=3.4+/-0.1 and BOECP4OP=3.5+/-0.1; P<0.05). These results demonstrate that OP supplementation had no harmful effect on embryo development either in granulosa, where P4 is naturally synthesised, or in BOEC coculture systems. Also we can not confirm a direct association between high P4 concentrations and embryo survival during early stages, although P4 may influence early embryo development through different mechanisms mediated by the type of cells present.

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.

Sperm binding properties and secretory activity of the bovine oviduct immediately before and after ovulation

The possibility that differences in hormonal regimes between the two oviducts in the cow around ovulation affects secretory activity of the oviduct epithelial cells and/or sperm-oviduct binding was studied. Oviducts were collected immediately after slaughter at 6 hr before to 5 hr after timed ovulation of 14 normally cyclic cows that had been inseminated (n = 6) or not (n = 8) and material obtained from the same cows was processed in three ways. First, in vivo, after artificial insemination of the cows, low numbers of sperm cells (approx. 15 per oviduct) were found within the entire oviducts as observed by scanning electron microscopy (SEM). Almost all sperm were located in the isthmus and then only on ciliated cells and showed without exception fully matured, intact morphology. Secretory activity of noninseminated oviduct epithelia was induced after ovulation which was most predominant in the pockets of the ipsi-lateral ampulla compared to the contra-lateral ampulla (P < 0.01). Second, ex vivo, explants dissected from oviducts of the noniseminated cows were incubated with sperm. In all cases, the sperm bound to the explants in a similar pattern as observed in vivo and this binding was strictly fucose-dependent. The main difference with in vivo experiments was the high numbers of sperm bound at any site of the oviduct ( approximately 3,000 cells per mm(2)) indicating the high sperm binding capacity of the oviduct epithelia. Ovulation induced a striking drop in sperm binding capacity in the oviducts and was most pronounced in the isthmus ( approximately 1,300 cells per mm(2); P < 0.001) and to a lesser extent in the ampulla ( approximately 2,000 cells per mm(2), P < 0.01). Third, in vitro, pieces of tissue dissected from oviducts of the noninseminated cows were cultured to mono-layers. Culturing epithelial cells resulted in loss of their normal morphological appearance. In all cases, the sperm binding capacity in monolayers was very low (<50 cells per mm(2)) when compared to corresponding explants (P < 0.0001). Sperm binding to monolayers originating from the isthmus (<25 cells per mm(2)) was lower than in those from the ampulla (40-50 cells per mm(2); P < 0.01) and remained similar after ovulation. In all three approaches, no significant differences were found in sperm-oviduct binding characteristics and sperm-distribution in the ipsi- versus contra-lateral oviducts. This indicates, that systemic endocrine changes around ovulation rather than specific oviduct changes at the ipsi-lateral oviduct induce secretion in oviduct epithelial cells, and thus induce sperm release.

Effect of morphological properties of transferred embryonic stages on tubal migration

In cattle, there is no practical method, which allows tubal transfer of pre-implantation embryos for routine in vivo culture as it has been established in sheep. The aim of our study was to perform tubal transfer by transvaginal endoscopy in synchronized heifers, in order to expose embryos at various embryonic stages to the physiological mechanisms of migration in the non-ligated oviducts. Various embryonic stages were transferred by transvaginal endoscopy into the oviducts of temporary recipients and were recovered on Day 7. The transfer of embryos in hyaluronate containing medium ("Hyaluronan"), zygotes stripped of cumulus ("Denuded Zygotes"), embryos embedded in cumulus ("Zygotes with Cumulus"), matured oocytes with capacitated spermatozoa ("GIFT") or embryos embedded in Na alginate ("Alginate") led to increasing recovery rates (13, 30, 56, 63 and 71%, respectively). However, the developmental rate on Day 7 was adversely affected (16, 11, 8, 16 and 8%), whereas the blastocyst rate on Day 8 showed more balanced results (17, 14, 18, 21 and 11%). Our data demonstrate that the structural properties of transferred embryos affect tubal migration and are crucial for subsequent in vivo culture. Embryos enclosed in cumulus cells or alginate synchronize more successfully with the oviductal transport systems than denuded stages or embryos in hyaluronate containing medium.

Anatomicohistological Characteristics of the Tubular Genital Organs of the Female Collared Peccary (Tayassu tajacu) from North-eastern Amazon

The present study examines anatomical and histological characteristics of tubular genital organs and its relationships with the reproductive state of 24 wild adult collared peccary (Tayassu tajacu) females. The tunica mucosa of the uterine tube presents a pseudostratified, intermittently ciliated columnar epithelium. The epithelial secretory cells of pregnant females and females in the luteal phase of the oestrous cycle became taller than the ciliated cells and showed abundant apical secretory blebs, whereas secretory cells of females in the follicular phase showed abundant mucous secretory activity (periodic acid-Schiff positive cells). The uterus is composed of two narrow and convoluted uterine horns, separated by the velum uteri, a small uterine body and a long and muscular cervix. The endometrial lining of both uterine horns and body is a monostratified, columnar ciliated epithelium. Pregnant females and females in luteal phase showed a more developed hyperplasia of the endometrial simple tubular glands than females in the follicular phase. The cervix presents interdigitated rows of mucosal prominences that project into the lumen, structures similar to pulvini cervicali, occluding the cervical canal. In pregnant females, the endocervical canal was filled by a viscous cervical secretion. Females in follicular phase presented a thicker vaginal epithelium than pregnant females and females in luteal phase. The present study suggests that the collared peccary female showed different histological features of the uterine tubes, uterus and vagina in accordance with the reproductive state of the females.

Colocalization of chromogranin A and inositol 1,4,5-trisphosphate receptor in ciliated cells of the bovine oviduct

Previous investigations of the expression of chromogranin A (CgA) have been performed primarily in neuroendocrine tissues containing amine and peptide secretory vesicles. More recently it has been shown that CgA, as a high capacity Ca2+ storage protein, interacts with the inositol 1,4,5-trisphosphate receptor/Ca2+ channel (InsP3R) which has been found to be selectively localized in oviductal cells of the mouse. To examine a possible role of this coupling in the Ca2+-dependent ciliary movement, we investigated the topographical and cellular distribution of cells positive for CgA and inositol 1,4,5-trisphosphate receptor type 2 (InsP3R2) in the bovine oviduct at different stages of the oestrous cycle. Using immunohistochemical techniques on paraffin-embedded tissue we have successfully shown that CgA is selectively expressed in ciliated cells of the bovine oviduct. The labelled cells show intense positive staining in the apical surface area in close vicinity to the ciliary apparatus. CgA-positive ciliated cells are most frequently observed at dioestrous while a lower number appears at oestrous. Additionally, secretory and intraepithelial neuroendocrine cells consistently do not stain with the CgA-antiserum. We then investigated whether the reported expression of the InsP3R in oviductal cells of the mouse corresponds to the expression of the InsP3R in bovine oviductal cells. Using a polyclonal antibody to the type 2 InsP3R, we found that the receptor is also selectively expressed in a similar matter to CgA in the apical cytoplasm of ciliated cells. This is the first morphological demonstration of the colocalization of CgA and InsP3R in epithelial ciliated cells of the bovine oviduct. Our results suggest that CgA and InsP3R could be involved in controlling the ciliary activity of oviductal epithelial cells.

Study of the functional anatomy of bovine oviductal mucosa

The oviducts of 31 cyclic cows were examined to study the structure and nature of the oviductal mucosa. The general distribution of spermatozoa within the oviductal mucosa was studied in five additional cows. The oviductal infundibulum is an asymmetric funnel-shaped structure surrounding the ostium. It is divided along the free boarder of the mesosalpinx and presents one wide and one narrow side. The mucosa of the wide side possesses a system of low interconnected cords that converge distally forming primary folds. The folds on the narrow side start sharply from the free margin and fuse toward the ostium abdominale. Areas between folds throughout the lumen of the oviduct show a high degree of complex organization. Interfold spaces are occupied by secondary and small interconnected folds which join to form a system of cul-de-sacs. In the infundibulum, these cul-de-sacs open toward the ovary, while cul-de-sacs present in the caudal isthmus and in the UTJ open toward the uterus. Marked variations were observed in the oviductal epithelium depending on the oviductal segment, basal or apical areas of the folds, and phase of the oestrous cycle. Near to the time of ovulation, numerous spermatozoa were found in the periphery of the caudal isthmus within pockets of basal interfold areas, as well as within pockets and cul-de-sacs of the tubo-uterine junction. Individual spermatozoa were also observed in peripheral areas of the ampullary-isthmic junction and ampulla. The topography of the oviduct provides a complex system of regulation which may influence not only the passage of gametes and/or embryos, but also movement of fluid within the oviductal canal.

Ultrastructural features of goat oviductal secretory cells at follicular and luteal phases of the oestrous cycle

The aim of the present study was to investigate the ultrastructure of secretory cells in the various regions of the goat oviduct during the follicular and luteal phases of the oestrous cycle. During the follicular phase in the fimbriae, the secretory cells contained small secretory granules with electron-dense matrices. In the luteal phase, the secretory granules disappeared and cytoplasmic protrusions, extending beyond the luminal border of the ciliated cells and often containing the nucleus, were predominant. During the follicular phase in ampullary 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 ampullary secretory cells at the luteal phase. Conspicuous cytoplasmic protrusions of secretory cells were observed similar to those of the fimbrial epithelium. Isthmic cells were almost free of secretory granules and lysosome-like bodies were found both at the follicular and luteal phases. In conclusion, our ultrastructural observations of goat oviduct revealed marked cyclic changes in the ultrastructural features of secretory cells and the ultrastructural features and the numbers of secretory granules were distinctive for each particular segment.

Development of in vitro matured and fertilized bovine embryos cocultured with bovine oviductal epithelial cells obtained from oviducts ipsilateral to cystic follicles

The present experiment was conducted to clarify the effect of bovine oviductal epithelial cells (BOEC) collected from oviducts ipsilateral to cystic follicles (CFs) using an in vitro coculture system on the development of in vitro matured/fertilized (IVM/IVF) bovine embryos. In the first comparison, the effect of the presence of CF on the development of the embryos cocultured with BOEC derived from the cows with CF (n = 18) and corpus hemorrhagicum (CH, n = 10) was examined. In the second comparison, the effect of the type of cyst [progesterone (P4)-dominant; n = 9, estradiol-17beta (E2)-dominant; n = 5] on the development of the embryos cocultured with BOEC derived from the cystic cows was examined. No difference was observed between CF and CH (control) groups in the mean developmental rates of embryos developed to > or =2-cell (86.3% vs. 86.4%), 8-16 cells (53.0% vs. 56.2%), blastocyst (24.2% vs. 24.8%) and hatched blastocyst (12.0% vs. 14.6%). However, the blastocyst production rate was significantly different (P<0.05) between the P4-dominant (19.8%) and E2-dominant (32.6%) groups. The rate of development from cleavage stage embryo to blastocyst was significantly different between P4-dominant (22.9%) and E2-dominant (37.9%) groups. Moreover, the blastocyst rate from 8-16 cells of E2-dominant group (61.6%) was significantly higher than that of P4-dominant one (39.5%). These results indicate that the effects of BOEC collected from oviduct ipsilateral to CFs on embryo development are variable, and the variability is closely associated with the steroid hormone profiles of the follicular fluid.

Effect of ovarian steroids and oxytocin on the production of prostaglandin E2, prostaglandin F2alpha and endothelin-1 from cow oviductal epithelial cell monolayers in vitro

Cyclic physio-anatomical variation in the oviducts is mediated by the local countercurrent transfer of ovarian products. Thus, in this study cow oviductal epithelial cells (COEC) culture were utilized to investigate the effects of ovarian products such as progesterone (P4), estradiol 17beta (E2) and oxytocin (OT) on local oviductal prostaglandin E2 (PGE2), F2alpha (PGF2alpha) and endothelin-1 (ET-1) production. COEC were collected from non-pregnant Holstein cows (n = 8) during the follicular phase and cultured in M199 under standard culture conditions until monolayer formation. Cells in first passage were incubated for 24 or 48 h with P4 (500 ng/ml), E2 (1 ng/ml), OT (10(-9) M) or combination of E2 + P4. Administration of E2 significantly increased the production of PGE2, PGF2alpha and ET-1. However, simultaneous administration of P4 blocked the effect of E2. OT did not show any effect on oviductal productions of either PGs or ET-1. The results of this study show that E2 stimulates PG and ET-1 production by COEC in vitro. Thus, it can be suggested that locally transferred E2 from the ovarian follicles may be important for oviductal contraction and gamete/zygote transport during the peri-ovulatory period.

Local distributions of oviductal estradiol, progesterone, prostaglandins, oxytocin and endothelin-1 in the cyclic cow

The cyclic patterns of hormones which regulate the activity of the oviduct in the cow have not been adequately reported. We studied progesterone (P4), estradiol 17 beta (E2), prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2 alpha), oxytocin (OT) and endothelin-1 (ET-1) concentrations in the cow oviduct. Reproductive tracts from cyclic Holstein cows in the follicular phase (n = 5), post ovulation phase (n = 5) and luteal phase (n = 5) were collected at a slaughterhouse. Oviducts were separated from the uterus, the lumen vas washed with physiological saline, and the enveloping connective tissues were removed. The fimbria was then separated at first and then the rest was divided into 2 parts of equal length (proximal and distal). After extraction, levels of different hormones in the tissues were measured using double antibody enzyme immunoassays (EIAs). There were no differences in any hormone concentration between the 3 parts of the oviduct at any stage of the estrous cycle. The highest concentration of oviductal P4 was observed during the luteal phase and in the oviduct ipsilateral to the functioning CL. Oviductal OT was unchanged throughout the cycle. The highest E2 concentration was observed during the follicular phase in the oviduct ipsilateral to the dominant follicle. The oviduct ipsilateral to the dominant follicle during the follicular phase and ipsilateral to the ovulation site post ovulation showed higher levels of PGE2, PGF2 alpha and ET-1 than those on the contralateral side or during the luteal phase. The highest PGE2 was observed in the oviduct ipsilateral to the ovulation site during the post ovulation phase. The results suggest that the ovarian products (P4, OT and E2) and the local oviductal products (PGE2, PGF2 alpha, and ET-1) may synergistically control oviductal contraction for optimal embryo transport during the periovulatory period, and provide further evidence for the local delivery of ovarian steroids to the adjacent reproductive tract.

Correlations between chemical parameters, mitogenic activity and embryotrophic activity of bovine oviduct-conditioned medium

To establish parameters predicting the quality of bovine oviduct epithelial cell-conditioned media, we compared media conditioned by oviduct cells from cows at Day 2 (n = 3) and Day 15 (n = 3) of the estrous cycle. In addition, we tested the influence of time of conditioning. Media were evaluated for their embryotrophic activity using a cumulus cell co-culture system as a control. The same media were tested for their mitogenic activity on NIH 3T3 cells and for chemical parameters, including total protein, and de novo synthesized protein as well as for concentrations of glucose, lactate and ammonium. Analysis of variance did not reveal a significant effect by stage of the estrous cycle on the embryotrophic activity of conditioned media. However, there was a significant effect by time of conditioning on the proportion of 5- to 8-cell embryos (P < 0.01) and of blastocysts and hatched blastocysts (P < 0.05). None of the conditioned media (19 to 31% blastocysts) was superior to the cumulus cell co-culture system (32% blastocysts). In the conditioned media, the proportion of 5- to 8-cell embryos correlated positively with mitogenic activity on 3T3 cells (r = 0.64; P < 0.05), whereas the proportion of blastocysts was not significantly correlated with this parameter. In summary, our results provide evidence for an effect of time of conditioning on embryotrophic activity of oviduct epithelial cell-conditioned media. The fact that mitogens for NIH 3T3 cells affect the proportion of 5- to 8-cell embryos but not of blastocysts suggests different culture requirements for early and late preimplantation stage development of bovine embryos.

Morphological features of epithelial cells in the sheep isthmus oviduct during early pregnancy

BACKGROUND

The objective of the present study was to define the morphological changes that occur in the epithelium of the isthmus oviduct of the sheep during the first few weeks of pregnancy.

MATERIALS

Isthmus oviducts were obtained from ovariectomized, estrous (day O) and pregnant (day 2, 3, 4, 6, and 16) ewes and analyzed using light and electron microscopy.

RESULTS

The epithelium was low cuboidal in the isthmus from ovariectomized sheep, significantly increased in height at estrus, underwent an additional increase at day 3, and was significantly reduced by day 4 of pregnancy. Ciliated and nonciliated epithelial cells were present at all reproductive stages. Ciliated cells were always the predominant cell type. The percentage of ciliated and nonciliated cells did not significantly change at any stage examined. In addition, a third cell type, located adjacent to the basement membrane, was present. These "basal" cells were rounded in appearance and more frequently observed in the epithelial lining of ovariectomized ewes and after day 3 of pregnancy. The secretory organelles of nonciliated epithelial cells obtained from ovariectomized ewes were poorly developed. In estrous ewes, the Golgi apparatus in nonciliated cells consisted of stacked cisternae that atrophied later in pregnancy. The most striking alterations in the secretory apparatus occurred in ciliated cells. Two populations of ciliated cells were observed at estrus-one with abundant, membrane bound supranuclear granules and one without granules. The granules in ciliated cells were rare after day 3 of pregnancy and no evidence of secretion was ever observed. Large lipid droplets were present in the cytoplasm of ciliated cells at estrus. Lysosomes were abundant in nonciliated cells by day 16 of pregnancy. Regularly arranged microvilli were present in nonciliated cells obtained from ovariectomized, estrous, and pregnant ewes. No appreciable change in nuclear shape or chromatin content was observed at any reproductive stage examined. The ultrastructural characteristics and relative abundance of other cytoplasmic organelles such as the RER, SER, mitochondria, and glycogen varied slightly during pregnancy in ciliated and nonciliated cells.

CONCLUSIONS

These data show that the epithelial lining of the isthmus oviduct in the sheep undergoes subtle, yet distinctive, structural changes during the first few weeks of pregnancy.

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.

Capacitation in vitro of bovine spermatozoa by oviduct epithelial cell monolayer conditioned medium

The effect of the active capacitating factor secreted from oviduct epithelial cell monolayers (OECM) in different environments on in vitro fertilization was evaluated. Capacitation was determined as the ability of sperm to fertilize bovine oocytes in vitro. When the mTALP was supplemented with glucose during conditioning, the sperm penetration rate was significantly reduced (P < 0.05) compared to the control (7% +/- 1 vs. 30% +/- 4). The percentages of sperm penetrated oocytes were higher following insemination in the OECM-conditioned medium derived from the early stage (48% +/- 7) of the estrous cycle than in the OECM-conditioned medium derived from either mid (35% +/- 2) or late stages (28% +/- 3) of the estrous cycle. When the medium was supplemented with 0.1 or 0.5 microgram/ml estradiol-17 beta during medium conditioning, sperm penetration rates increased (P < 0.05) compared to the control group (55% +/- 4 vs. 40% +/- 3 and 54% +/- 2 vs. 41% +/- 3, respectively). In addition, the percentages of penetrated oocytes significantly decreased (P < 0.05) following insemination when the OECM-conditioned medium was added to 0.01%, 0.05%, and 0.1% ethanol compared to the control (25% +/- 4, 19% +/- 2, 18% +/- 3, and 45% +/- 3, respectively). Sperm penetration rates significantly (P < 0.01) decreased when the OECM-conditioned medium was heated to 100 degrees C for 5 min (10% +/- 1 vs. 40% +/- 3). These results suggest that the active capacitating factor was secreted by the OECM and that this capacitating factor in the OECM-conditioned medium was inhibited by the presence of glucose. This factor was found to be heat-sensitive and its action was affected by ethanol. The OECM derived from the three phases of the estrous cycle as well as the presence of estradiol-17 beta influenced the capacity of the OECM to secrete this capacitating factor in vitro.