The mammalian oviduct: biochemistry and physiology

Fallopian tube rheology regulates epithelial cell differentiation and function to enhance cilia formation and coordination

The rheological properties of the extracellular fluid in the female reproductive tract vary spatiotemporally, however, the effect on the behaviour of epithelial cells that line the tract is unexplored. Here, we reveal that epithelial cells respond to the elevated viscosity of culture media by modulating their development and functionality to enhance cilia formation and coordination. Specifically, ciliation increases by 4-fold and cilia beating frequency decreases by 30% when cells are cultured at 100 mPa·s. Further, cilia manifest a coordinated beating pattern that can facilitate the formation of metachronal waves. At the cellular level, viscous loading activates the TRPV4 channel in the epithelial cells to increase intracellular Ca2+, subsequently decreasing the mitochondrial membrane potential level for ATP production to maintain cell viability and function. Our findings provide additional insights into the role of elevated tubal fluid viscosity in promoting ciliation and coordinating their beating-a potential mechanism to facilitate the transport of egg and embryo, suggesting possible therapeutic opportunities for infertility treatment.

Metabolic stressful environment drives epigenetic modifications in oviduct epithelial cells

The oviduct provides a suitable microenvironment from the gametes' final maturation until initial embryo development. Dynamic functional changes are observed in the oviduct cells, mainly controlled by steroid hormones and well-orchestrated during the estrous cycle. However, based on the roles played by the oviduct, additional layers of complexity might be present in its regulatory process. There is a cellular process that includes metabolic adaptation that can guide molecular modifications. This process is known as metaboloepigenetics. Therefore, we aimed to better understand how this crosstalk occurs in oviductal epithelial cells (OEC). Due to limited in situ access to the oviduct, we used the primary in vitro cell culture as a culture model and glucose as a metabolic disturbed factor. For that, cells derived from the oviductal epithelial layer were collected from cows at either follicular or luteal stages (n = 4 animals per group). They were cultured on a monolayer culture system under normoglycemic (2.7 mM glucose) or hyperglycemic conditions (27 mM glucose). On day five of culture, attached cells were submitted to analysis of mitochondrial metabolism (mitochondrial membrane potential - MMP) and epigenetics markers (5- methylcytosine - 5 mC and histone 3 lysine 9 acetylation - H3K9ac). Moreover, the culture media were submitted to the metabolites analysis profile by Raman spectrometry. Data were analyzed considering the effect of glucose level (normoglycemic vs. hyperglycemic), stages when OEC were harvested (follicular vs. luteal), and their interaction (glucose level * cycle stage) by two-way ANOVA. As a result, the high glucose level decreased the H3K9ac and MMP levels but did not affect the 5 mC. Regardless of the metabolic profile of the culture media, the glucose level was the only factor that changed the Raman shifts abundance. Although this present study evaluated oviductal epithelial cells after being submitted to an in vitro monolayer culture system, which is known to lead to cell dedifferentiation, yet, these results provide evidence of a relationship between epigenetic reprogramming and energy metabolism under these cell culture conditions. In conclusion, the levels of metabolites in culture media may be crucial for cellular function and differentiation, meaning that it should be considered in studies culturing oviductal cells.

Revolutionizing the female reproductive system research using microfluidic chip platform

Comprehensively understanding the female reproductive system is crucial for safeguarding fertility and preventing diseases concerning women's health. With the capacity to simulate the intricate physio- and patho-conditions, and provide diagnostic platforms, microfluidic chips have fundamentally transformed the knowledge and management of female reproductive health, which will ultimately promote the development of more effective assisted reproductive technologies, treatments, and drug screening approaches. This review elucidates diverse microfluidic systems in mimicking the ovary, fallopian tube, uterus, placenta and cervix, and we delve into the culture of follicles and oocytes, gametes' manipulation, cryopreservation, and permeability especially. We investigate the role of microfluidics in endometriosis and hysteromyoma, and explore their applications in ovarian cancer, endometrial cancer and cervical cancer. At last, the current status of assisted reproductive technology and integrated microfluidic devices are introduced briefly. Through delineating the multifarious advantages and challenges of the microfluidic technology, we chart a definitive course for future research in the woman health field. As the microfluidic technology continues to evolve and advance, it holds great promise for revolutionizing the diagnosis and treatment of female reproductive health issues, thus propelling us into a future where we can ultimately optimize the overall wellbeing and health of women everywhere.

Decreased acetylation of HDGF improves oviduct production in Rana dybowskii, Rana amurensis, and Rana huanrenensis

The oviduct of female Rana dybowskii is a functional food and can be used as a component of Traditional Chinese medicine. The differentially expressed genes enriched was screened in cell growth of three Rana species. We quantitatively analyzed 4549 proteins using proteomic techniques, enriching the differentially expressed proteins of Rana for growth and signal transduction. The results showed that log2 expression of hepatoma-derived growth factor (HDGF) was increased. We further verified 5 specific differential genes (EIF4a, EIF4g, HDGF1, HDGF2 and SF1) and found that HDGF expression was increased in Rana dybowskii. Through acetylation modification analysis, we identified 1534 acetylation modification sites in 603 proteins, including HDGF, and found that HDGF acetylation expression was significantly reduced in Rana dybowskii. Our results suggest that HDGF is involved in the development of oviductus ranae, which is regulated by acetylation modification.

The interaction between the environment and embryo development in assisted reproduction

It can be assumed that the natural processes of selection and developmental condition in the animal provide the best prerequisites for embryogenesis resulting in pregnancy and subsequent birth of a healthy neonate. In contrast, circumventing the natural selection mechanisms and all developmental conditions in a healthy animal harbors the risk of counteracting, preventing or reducing the formation of embryos or substantially restricting their genesis. Considering these facts, it seems to be obvious that assisted reproductive techniques focusing on early embryonic stages serve an expanded and unselected germ cell pool of oocytes and sperm cells, and include the culture of embryos outside their natural habitat during and after fertilization for manipulation and diagnostic purposes, and for storage. A significant influence on the early embryonic development is seen in the extracorporeal culture of bovine embryos (in vitro) or stress on the animal organism (in vivo). The in vitro production per se and metabolic as well as endocrine changes in the natural environment of embryos represent adequate models and serve for a better understanding. The purpose of this review is to give a brief presentation of recent techniques aimed at focusing more on the complex processes in the Fallopian tube to contrast in vivo and in vitro prerequisites and abnormalities in early embryonic development and serve to identify potential new ways to make the use of ARTs more feasible.

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.

In vivo dynamic 3D imaging of oocytes and embryos in the mouse oviduct

Developmental biologists have always relied on imaging to shed light on dynamic cellular events. However, processes such as mammalian fertilization and embryogenesis are generally inaccessible for direct imaging. In consequence, how the oviduct (fallopian tube) facilitates the transport of gametes and preimplantation embryos continues to be unanswered. Here we present a combination of intravital window and optical coherence tomography for dynamic, volumetric, in vivo imaging of oocytes and embryos as they are transported through the mouse oviduct. We observed location-dependent circling, oscillating, and long-distance bi-directional movements of oocytes and embryos that suggest regulatory mechanisms driving transport and question established views in the field. This in vivo imaging approach can be combined with a variety of genetic and pharmacological manipulations for live functional analysis, bringing the potential to investigate reproductive physiology in its native state.

Wang and Larina present in vivo volumetric imaging of oocytes and embryos as they are transported through the mouse oviduct with optical coherence tomography and an intravital microscopy. The study reveals complex dynamics of oocytes and embryos that suggest a regulatory role of cilia and oviductal contractions in driving the transport.

Sperm-Driven Micromotors Moving in Oviduct Fluid and Viscoelastic Media

Biohybrid micromotors propelled by motile cells are fascinating entities for autonomous biomedical operations on the microscale. Their operation under physiological conditions, including highly viscous environments, is an essential prerequisite to be translated to in vivo settings. In this work, a sperm-driven microswimmer, referred to as a spermbot, is demonstrated to operate in oviduct fluid in vitro. The viscoelastic properties of bovine oviduct fluid (BOF), one of the fluids that sperm cells encounter on their way to the oocyte, are first characterized using passive microrheology. This allows to design an artificial oviduct fluid to match the rheological properties of oviduct fluid for further experiments. Sperm motion is analyzed and it is confirmed that kinetic parameters match in real and artificial oviduct fluids, respectively. It is demonstrated that sperm cells can efficiently couple to magnetic microtubes and propel them forward in media of different viscosities and in BOF. The flagellar beat pattern of coupled as well as of free sperm cells is investigated, revealing an alteration on the regular flagellar beat, presenting an on-off behavior caused by the additional load of the microtube. Finally, a new microcap design is proposed to improve the overall performance of the spermbot in complex biofluids.

Review: Environmental impact on early embryonic development in the bovine species

Assisted reproduction techniques (ARTs) provide access to early stage embryos whose analysis and assessment deliver valuable information. The handling of embryos, including the in vitro production of bovine embryos, is a rapidly evolving area which nonetheless exposes the embryos to unnatural conditions for a period of time. The Fallopian tube provides innumerable quantitative and qualitative factors, all of which guarantee the successful development of the embryo. It is well known that the Fallopian tube can be bypassed, using embryo transfer, resulting in successful implantation in the target recipient animal and the birth of calves. However, the question arises as to whether such circumvention has a negative impact on the embryo during this sensitive development period. First crosstalk between the embryo and its environment confirms mutual recognition activities and indicate bilateral effects. Nowadays, in vitro production of bovine embryos is a well-established technology. However, it is still evident that in vitro generated embryos are not qualitatively comparable to embryos obtained ex vivo. To counteract these differences, comparative studies between in vitro and ex vivo embryos are advantageous, as embryos grown in their physiological environment can provide a blueprint or gold standard against which to compare embryos produced in vitro. Attempts to harness the bovine oviduct were sometimes very invasive and did not result in wide acceptance and routine use. Long-term development and refinement of transvaginal endoscopy for accessing the bovine oviduct has meanwhile been routinely applied for research as well as in practice. Comparative studies combining in vitro development with development in the cattle oviduct revealed that the environmental conditions to which the embryo is exposed before activation of the embryonic genome can have detrimental and lasting effects on its further development. These effects are manifested as deviations in gene expression profiles and methylation signatures as well as frequency of whole chromosomal or segmental aberrations. Furthermore, it was shown that hormonal superstimulation (multiple ovulation and embryo transfer), varying progesterone concentrations as well as metabolic disorders caused by high milk production, markedly affected embryo development in the postpartum period. Assisted reproductive techniques that allow the production and handling of extra numbers of generated embryos promise to have a very high impact on scientific and practical application. Any influence on the early embryonic life, both in animals and in vitro, is accompanied by a sensitive change in embryonic activity and should be assessed in vivo on the basis of physiological conditions before being used for ART.

Fallopian tube initiation of high grade serous ovarian cancer and ovarian metastasis: Mechanisms and therapeutic implications

Ovarian cancer is the most lethal gynecologic malignancy and the fifth leading cause of cancer-related death in women. Although outcomes have improved in recent years, there remains an unmet clinical need to understand the early pathogenesis of ovarian cancer in order to identify new diagnostic approaches and agents of chemoprevention and chemotherapy. While high grade serous ovarian cancer (HGSOC), the most abundant histotype, was initially thought to arise from the ovarian surface epithelium, there is an increasing body of evidence suggesting that HGSOC originates in the fallopian tube. With this new understanding of cell of origin, understanding of disease development requires analysis with a novel perspective. Currently, factors that drive the initiation and migration of dysplastic tubal epithelial cells from the fallopian tube to the ovary are not yet fully defined. These factors include common mutations to fallopian tube epithelial cells, as well as factors originating from both the fallopian tube and ovary which are capable of inducing transformation and dissemination in said cells. Here, we review these changes, their causative agents, and various potential means of intervention.

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.

Estradiol and Progesterone Induced Differentiation and Increased Stemness Gene Expression of Human Fallopian Tube Epithelial Cells

Fallopian tube epithelial cells (FTECs) are thought to be the origin of epithelial ovarian cancer. However, the effect of the hormones on FTECs is unknown, and therefore, this study explored this effect. We successfully derived FTECs from the fallopian tube epithelial layer and treated them with estradiol and progesterone. Reverse transcription polymerase chain reaction was used to evaluate the gene expression of the FTECs' hormone receptors. Confocal and electron microscopy were used to evaluate the morphology of the FTECs after they were treated with hormones. Finally, quantitative PCR was used to evaluate the gene expression of the hormone-treated FTECs. The results showed that the FTECs exhibited cuboidal cell morphology and could be maintained at a constant proliferation rate. Furthermore, flow cytometry revealed that the FTECs expressed stem cell markers, such as SSEA3, SSEA4, and Lgr5. Moreover, the FTECs could express both estrogen and progesterone receptors. In a culture treated with 400 nM estrogen, the FTECs differentiated toward ciliated cells, whereas in a culture treated with estradiol or progesterone, the FTECs increased their expression of certain stem cell markers (SSEA3, SSEA4, and Aldh1) and stemness genes [Wnt (AXIN2, LGR5, LGR6, and OLFM4) and Notch (Hes1) signaling]. In conclusion, hormones may alter the gene expressions of FTECs, and these cells may provide new insights into how FTECs regenerate in response to hormones.

Can the antral follicular count modulate the gene expression of bovine oviducts in Aberdeen Angus and Nelore heifers?

The number of visible ovarian antral follicles (antral follicle count—AFC) is repeatable in bovine individuals, but highly variable between animals, and with differences between Bos taurus and Bos indicus breeds. Several studies have tried to determine the correlation between AFC and increased fertility in cattle. While the impacts of AFC on embryo production, hormonal levels, and pregnancy rates have been described, the molecular effects of AFC on bovine oviducts have not yet been investigated. Here, the aim was to investigate the impact of breeds, such as Aberdeen Angus and Nelore heifer with high or low AFC, on abundance of transcripts and protein related to oviductal transport, sperm reservoir formation, monospermy control, and gamete interaction in the oviducts. In summary, the ovulation side was the major factor that affected transcript abundance on bovine oviducts. However, a discreet effect among AFC and cattle breeds was also observed. Based on this, we concluded and reinforced here that differential microenvironments between ipsilateral and contralateral oviducts have a major effect on modulating the transcripts related to oviductal transport, sperm reservoir formation, monospermy control, and gamete interaction. However, we cannot exclude that there is minimal effect of AFC or breed on regulation of some genes (such as AGTR1, ACE1, FUCA1, and VEGFA) in bovine oviducts.

Integrated transcriptomes throughout swine oestrous cycle reveal dynamic changes in reproductive tissues interacting networks

Female fertility is a highly regulated process involving the synchronized activities of multiple tissues. The underlying genomic regulation of the tissue synchronization is poorly understood. To understand this better we investigated the transcriptomes of the porcine ovary, endometrium, and oviduct at days 0, 3, 6, 9, 12, 15, or 18 of the oestrous cycle. We analysed the transcriptome profiles of the individual tissues and focus on the bridging genes shared by two or more tissues. The three tissue-networks were connected forming a triangular shape. We identified 65 bridging genes with a high level of connectivity to all other genes in the network. The expression levels showed negative correlations between the ovary and the other two tissues, and low correlations between endometrium and oviduct. The main functional annotations involved biosynthesis of steroid hormones, cell-to-cell adhesion, and cell apoptosis, suggesting that regulation of steroid hormone synthesis and tissue viability are major regulatory mechanisms.

Effects of surrounding fluid on motility of hyperactivated bovine sperm

Mammalian spermatozoa in organisms with internal fertilization are required to swim in the cervical and oviductal mucus, whose rheological properties differ substantially from those of water. Moreover, on the way to the oviduct, a change in sperm motility called hyperactivation may occur. In the present study, we focused on the motion characteristics of hyperactivated bovine sperm and investigated the effect of the surrounding fluid on motility. We prepared two kinds of polyacrylamide with high-viscosity non-Newtonian fluid properties, similar to the actual cervical and oviductal mucus. Using semen from Japanese cattle, we evaluated curvilinear velocity (VCL), straight-line velocity (VSL), and average path velocity (VAP). Additionally, we estimated linearity (LIN), straightness (STR), and wobble (WOB) as sperm motility parameters for several surrounding fluids. We successfully induced hyperactivation of bovine sperm in high-viscosity non-Newtonian fluid. Hyperactivation resulted in an increase in VCL and a decrease in VSL. In the high-viscosity non-Newtonian fluid, the hyperactivated sperm moved in a zig-zag pattern with regularity, different from the movement observed in a diluted solution. The increase in WOB in the non-Newtonian fluid suggests that hyperactivated sperm efficiently progress along the groove that exists on the oviductal mucus wall. These results improve our understanding of the motility of bovine sperm when they undergo hyperactivation in the actual cervical and oviductal mucus.

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.

Effect of bovine oviductal extracellular vesicles on embryo development and quality in vitro

The aim of this study was to evaluate the effect of extracellular vesicles (EV) from oviductal fluid (OF), either from the ampulla or isthmus, on the development and quality of in vitro-cultured bovine embryos. Zygotes were cultured in synthetic oviduct fluid (SOF + 3 mg/mL BSA) without calf serum (C- group), in the presence of 3 × 10⁵ EV/mL from ampullary or isthmic OF at either 1 × 10⁴g (10 K) or 1 × 10⁵ g (100 K), and compared with SOF + 5% FCS (C+ group). OF-EV size and concentration were assessed by electron microscopy and nanotracking analysis system. Embryo development was recorded on Days 7-9, and blastocyst quality was assessed through cryotolerance and gene expression analysis. Lower blastocyst yield was observed on Day 7 in the C- and OF-EV groups (12.0-14.3%) compared with C+ (20.6%); however, these differences were compensated at Days 8 and 9 (Day 9: 28.5-30.8%). Importantly, the survival rate of blastocysts produced with isthmic 100 K OF-EV was higher than that of C+ and C- group at 72 h after vitrification and warming (80.1 vs 34.5 and 50.5% respectively, P < 0.05). In terms of gene expression, blastocysts produced in the presence of 100 K isthmic OF-EV upregulated the water channel AQP3 and DNMT3A and SNRPN transcripts compared with the C+, with the expression in C- being intermediate. The lipid receptor LDLR was downregulated in C+ compared with all other groups. In conclusion, the addition of oviductal fluid extracellular vesicles from isthmus, to in vitro culture of bovine embryos in the absence of serum improves the development and quality of the embryos produced.

Designing 3-Dimensional In Vitro Oviduct Culture Systems to Study Mammalian Fertilization and Embryo Production

The oviduct was long considered a largely passive conduit for gametes and embryos. However, an increasing number of studies into oviduct physiology have demonstrated that it specifically and significantly influences gamete interaction, fertilization and early embryo development. While oviduct epithelial cell (OEC) function has been examined during maintenance in conventional tissue culture dishes, cells seeded into these two-dimensional (2-D) conditions suffer a rapid loss of differentiated OEC characteristics, such as ciliation and secretory activity. Recently, three-dimensional (3-D) cell culture systems have been developed that make use of cell inserts to create basolateral and apical medium compartments with a confluent epithelial cell layer at the interface. Using such 3-D culture systems, OECs can be triggered to redevelop typical differentiated cell properties and levels of tissue organization can be developed that are not possible in a 2-D culture. 3-D culture systems can be further refined using new micro-engineering techniques (including microfluidics and 3-D printing) which can be used to produce ‘organs-on-chips’, i.e. live 3-D cultures that bio-mimic the oviduct. In this review, concepts for designing bio-mimic 3-D oviduct cultures are presented. The increased possibilities and concomitant challenges when trying to more closely investigate oviduct physiology, gamete activation, fertilization and embryo production are discussed.

Lysophosphatidic Acid Synthesis and its Receptors' Expression in the Bovine Oviduct During the Oestrous Cycle

Lysophosphatidic acid (LPA) is a naturally occurring simple phospholipid which in the bovine reproductive system can be produced in the endometrium, corpus luteum, ovarian follicle and embryo. In this study, we examined the possibility that LPA receptors are expressed, and LPA synthesized, in the bovine oviduct. We found that the concentration of LPA was highest in infundibulum in the follicular phase of the oestrous cycle and was relatively high during the early-luteal phase in all examined parts of the oviduct. We also documented that LPA synthesis engages both available pathways for LPA production. The autotaxin (ATX) protein expression was significantly higher in the infundibulum compared to the isthmus during the follicular phase of the oestrous cycle. During the early-luteal phase of the oestrous cycle, ATX and phospholipase A2 (PLA2) protein expression was highest in ampulla, although the expression of LPARs was not as dynamic as LPA concentration in the oviduct tissue, and we presume that in the bovine oviduct, the most abundantly expressed receptor is LPAR2. In conclusion, our results indicate that the bovine oviduct is a site of LPA synthesis and a target for LPA action in the bovine reproductive tract. We documented that LPAR2 is the most abundantly expressed in the bovine oviduct. We hypothesize that in the bovine oviduct, LPA may be involved in the transport of gametes, fertilization and cellular signalling between the oviduct and cumulus-oocyte complex.

Local effect of lysophosphatidic acid on prostaglandin production in the bovine oviduct

The mammalian oviduct plays an important role in the fertilisation and transport of gametes and embryo. Prostaglandins (PGs) are local mediators of oviductal functions and are involved in fertilisation and the transport of gametes and embryo. Lysophosphatidic acid (LPA), a kind of phospholipid, is involved in various physiological actions. We hypothesised that LPA regulates PG production in the bovine oviduct. To test this hypothesis, we examined the mRNA expression of LPA receptors (LPAR1-6) and LPA-producing enzymes (ATX, PLA1α, PLA1β) in ampullary and isthmic tissues and in cultured epithelial and stromal cells isolated from the bovine oviduct. We also investigated the effects of LPA on PG synthase expression and PG production in cultured cells. The mRNA of LPAR1-4, 6, ATX and PLA1α were expressed in cultured epithelial and stromal cells. The expressions of LPAR1-3 were significantly lower and the expression of LPAR4 was significantly higher in the isthmic than in the ampullary tissues. Lysophosphatidic acid significantly stimulated PG production in the cultured isthmic stromal cells. The overall findings suggest that LPA stimulates PG production via LPAR4 in the bovine oviduct. Since PGs are important for fertilisation and the transport of gametes and embryo, these findings show that locally produced LPA regulates oviductal functions.

Regulation of bovine oviductal NO synthesis by follicular steroids and prostaglandins

Nitric oxide (NO) is a regulator of sperm motility, oocyte/embryo survival, and waves of contraction/relaxation in mammalian oviducts. As follicles control oviductal functions by two routes at least, (1) a systemic way via blood vessels before ovulation, (2) a direct way by entering of follicular fluid through fimbria at ovulation, we hypothesized that NO synthesis in the bovine oviduct is regulated by follicular steroids and prostaglandins (PGs). Quantification of mRNA expressions in the ampullary tissues showed that inducible NO synthase (NOS2) mRNA expression was highest on the day of ovulation (day 0). By contrast, NOS2 mRNA expression in the isthmus was highest on days 5-6 and lowest on days 19-21. Endothelial NOS (NOS3) mRNA expressions in either the ampulla or the isthmus did not change during the estrous cycle. PGE2 and PGF2α increased NOS2 mRNA expressions in cultured ampullary oviductal epithelial cells after 1-h incubation. These increases were suppressed by an antagonist of E-prostanoid receptor type 2, one of the PGE2 receptor. Estradiol-17β decreased the expression of NOS2 mRNA expression in cultured isthmic epithelial cells 24h after treatment. This effect was suppressed by an antagonist of estrogen receptorα(ESR1). Expression of ESR1 was highest on days 19-21 in the isthmic tissues. The overall findings indicate region-specific difference of NO synthesis in the oviduct. PGs flowed from ruptured follicle may up-regulate NO synthesis in the oviductal epithelium, whereas circulating E2 seems to inhibit NO synthesis via ESR1 in the isthmus at the follicular stage.

Genome-wide transcriptional regulation of estrogen receptor targets in fallopian tube cells and the role of selective estrogen receptor modulators

Background

The fallopian tube epithelium is one of the potential sources of high-grade serous ovarian cancer (HGSC). The use of estrogen only hormone replacement therapy increases ovarian cancer (OVCA) risk. Despite estrogen’s influence in OVCA, selective estrogen receptor modulators (SERMs) typically demonstrate only a 20 % response rate. This low response could be due to a variety of factors including the loss of estrogen receptor signaling or the role of estrogen in different potential cell types of origin. The response of fallopian tube epithelium to SERMs is not known, and would be useful when determining therapeutic options for tumors arising from this cell type, such as HGSC.

Results

Using normal murine derived oviductal epithelial cells (mouse equivalent to the fallopian tube) estrogen receptor expression was confirmed and interaction with its ligand, estradiol, triggered mRNA and protein induction of progesterone receptor (PR). The SERMs 4-hydroxytamoxifen, raloxifene and desmethylarzoxifene, functioned as estrogen receptor antagonists in oviductal cells. Cellular proliferation and migration assays suggested that estradiol does not significantly impact cellular migration and increased proliferation. Further, using RNAseq, the oviduct specific transcriptional genes targets of ER when stimulated by estradiol and 4-hydroxytamoxifen signaling were determined and validated. The RNA-seq revealed enrichment in proliferation, anti-apoptosis, calcium signaling and steroid signaling processes. Finally, the ER and PR receptor status of a panel of HGSC cell lines was investigated including Kuramochi, OVSAHO, OVKATE, OVCAR3, and OVCAR4. OVSAHO demonstrated receptor expression and response, which highlights the need for additional models of ovarian cancer that are estrogen responsive.

Conclusions

Overall, the fallopian tube has specific gene targets of estrogen receptor and demonstrates a tissue specific response to SERMs consistent with antagonistic action.

Electronic supplementary material

The online version of this article (doi:10.1186/s13048-016-0213-3) contains supplementary material, which is available to authorized users.

Histochemical structure and immunolocalisation of the hyaluronan system in the dromedary oviduct

We investigated the local modulation of some histochemical properties of oviducts of the dromedary (Camelus dromedarius), focusing on the immnolocalisation of hyaluronic acid (HA) synthases (HAS2 and HAS3), hyaluronidases (HYAL2 and HYAL1) and the HA receptor CD44 in the ampulla and isthmus. Abundant acidic mucopolysaccharides (glycosaminoglycans) were detected by Alcian blue staining along the luminal surface of both ciliated and non-ciliated epithelial cells (LE). Staining for HAS2 was higher in the primary epithelial folds of the ampulla compared with the isthmus, especially in secretory cells, adluminal epithelial surface and supranuclear cell domain. HAS3 staining was stronger in the LE of the isthmus than ampulla. HYAL2 was detected in the LE in the ampulla and isthmus and was more intense in the adluminal projections of secretory cells. HYAL1 was weakly detected in the LE with no difference between the ampulla and isthmus. Strong CD44 immunostaining was present in the LE of the ampulla and isthmus. CD44 staining was higher in secretory cells than in ciliated epithelial cells and was higher in the supranuclear region than the basal region of the cytoplasm. In conclusion, we provide evidence that HA synthesis and turnover occur in the camel oviduct. Differences in HAS2 and HAS3 expression suggest regional differences in the molecular size of HA secreted in oviductal fluid that may influence oviduct–gamete interaction in the camel.

Soluble ligands and their receptors in human embryo development and implantation

Extensive evidence suggests that soluble ligands and their receptors mediate human preimplantation embryo development and implantation. Progress in this complex area has been ongoing since the 1980s, with an ever-increasing list of candidates. This article specifically reviews evidence of soluble ligands and their receptors in the human preimplantation stage embryo and female reproductive tract. The focus will be on candidates produced by the human preimplantation embryo and those eliciting developmental responses in vitro, as well as endometrial factors related to implantation and receptivity. Pathways to clinical translation, including innovative diagnostics and other technologies, are also highlighted, drawing from this collective evidence toward facilitating joint improvements in embryo quality and endometrial receptivity. This strategy could not only benefit clinical outcomes in reproductive medicine but also provide broader insights into the peri-implantation period of human development to improve fetal and neonatal health.

Effects of spermatozoa-oviductal cell coincubation time and oviductal cell age on spermatozoa-oviduct interactions

The oviduct plays a crucial role in sperm storage, maintenance of sperm viability and sperm transport to the site of fertilisation. The aim of the present study was to investigate the effects of oviductal cell culture passage number, oviductal cell age and spermatozoa-oviduct coincubation times on gene expression in oviductal cells. Immortalised oviductal epithelial cells (OPEC) obtained from two different cell passages (36 and 57) were subcultured three times with and without spermatozoa for 24 h (control group). In a second study, OPEC were cocultured with spermatozoa for different time intervals (0, 4, 12 and 24 h). Expression of adrenomedullin (ADM), heat shock 70 kDa protein 8 (HSPA8) and prostaglandin E synthase (PGES) in OPEC was measured by quantitative polymerase chain reaction. The expression of ADM and HSPA8 was decreased significantly in OPEC cells from Passage 57, particularly in the later subculture group. These effects on HSPA8, but not ADM, expression in OPEC were further altered after coculture with spermatozoa for 24 h. We also demonstrated that spermatozoa-oviduct coculture for 12 and 24 h resulted in significantly higher expression of ADM, HSPA8 and PGES in OPEC. Overall, the data suggest that the OPEC lose some of their properties as a result of oviductal cell aging and that there are spermatozoa-oviduct interactions leading to increased oviductal cell gene expression.

Effects of systemic progesterone during the early luteal phase on the availabilities of amino acids and glucose in the bovine uterine lumen

The uterine histotroph provides essential nutrition to the developing conceptus during the preimplantation period of pregnancy. The objective of the present study was to examine the effects of cycle stage and progesterone (P4) concentrations in the blood on the recoverable quantities of amino acids and glucose in the histotroph during the preimplantaion period of conceptus development. Following oestrus, dairy heifers were assigned to low, control or high P4 groups (n=6 heifers per treatment and time point). The uterine horn ipsilateral to the corpus luteum was flushed on either Day 7 or Day 13. The present study quantified 24 amino acids and glucose in the uterine flushings using HPLC and fluorometry, respectively. Heifers in the low P4 group had lower plasma concentrations of P4 throughout the cycle, whereas heifers in the high group had higher plasma concentrations of P4 between Days 3 and 7 compared with the control group (P<0.05). Total recoverable neutral (Ser, Gln, Gly, Thr, Cit, β-Ala, Tau, Ala, Tyr, Trp, Met, Val, Phe, Ile, Leu, Pro and Cys), acidic (Glu) and basic (His, Arg, Orn and Lys) amino acids were greater (P<0.05) on Day 13 than on Day 7. There was no significant difference in the amount of Asp or Asn between Day 7 and Day 13. The amount of amino acids recovered on Day 7 was similar across treatment groups. On Day 13, the amount of Asn, His and Thr was lower (P<0.05) in the low P4 heifers compared with the controls and/or high P4 heifers. Quantities of glucose were not altered by cycle stage or P4 treatment. In conclusion, the stage of oestrous cycle and P4 play important roles in modulating amino acids in the histotroph, a potentially critical factor for early embryonic and/or conceptus survival.

Summer heat stress affects prostaglandin synthesis in the bovine oviduct

Summer heat stress (HS) negatively affects reproductive functions, including prostaglandin (PG) F2α secretion in the endometrium, and decreases fertility in cattle. In the present study, we examined the effects of elevated temperatures on PG synthesis in oviductal epithelial cells. The epithelial cells obtained from the ampulla and isthmus of the oviduct were incubated at various temperatures (38.5, 39.5, 40.0, and 40.5 °C) for 24 h. In the ampulla, PGE2 concentration was higher at 40.5 °C than at 38.5 °C, while PGF2α production was not affected by the temperatures in this range. The expressions of microsomal PGE synthase 1 (PTGES (mPGES1)), cytosolic PGES (PTGES3 (cPGES)), and heat shock protein 90 (HSP90AA1 (HSP90)) mRNAs and proteins were higher at 40.5 °C than at 38.5 °C in the ampullary epithelial cells. Seasonal changes in the expressions of PGES and HSP90AA1 mRNAs in oviductal tissues were also investigated. The expressions of PTGES3 and HSP90AA1 mRNAs were higher in the ampullary tissues in summer than in winter. In summary, elevated temperatures stimulated PGE2 production in the ampullary oviduct by increasing the expressions of PGESs and HSP90AA1, which can activate cPGES. The overall results suggest that HS upsets PG secretions and reduces oviductal smooth muscle motility, which in turn could decrease gamete/embryo transport through the oviduct.

The human oviduct transcriptome reveals an anti-inflammatory, anti-angiogenic, secretory and matrix-stable environment during embryo transit

The human oviduct serves as a conduit for spermatozoa in the peri-ovulatory phase and nurtures and facilitates transport of the developing embryo for nidation during the luteal phase. Interactions between the embryo and oviductal epithelial surface proteins and secreted products during embryo transit are largely undefined. This study investigated gene expression in the human oviduct in the early luteal versus follicular phases to identify candidate genes and biomolecular processes that may participate in maturation and transport of the embryo as it traverses this tissue. Oviductal RNA was hybridized to oligonucleotide arrays and resulting data were analysed by bioinformatic approaches. There were 650 genes significantly down-regulated and 683 genes significantly up-regulated (P<0.05) in the luteal versus follicular phase. Quantitative real-time PCR, immunoblot analysis and immunohistochemistry confirmed selected gene expression and cellular protein localization. Down-regulated genes involved macrophage recruitment, immunomodulation and matrix-degeneration, and up-regulated genes involved anti-inflammatory, ion transport, anti-angiogenic and early pregnancy recognition. The oviduct displayed some similarities and differences in progesterone-regulated genes compared with the human endometrium. Together, these data suggest a unique hormonally regulated environment during embryo development, maturation and transport through human oviduct and some conservation of progesterone signalling in tissues of common embryological origin. The oviduct serves as a conduit for spermatozoa in the peri-ovulatory phase and it nurtures and facilitates transport of the developing embryo during the luteal phase of the menstrual cycle, although precise interactions between the embryo and oviductal epithelium and secreted products are largely undefined. Herein, we investigated gene expression in human oviduct to identify candidate genes and processes that may participate in maturation and transport of the embryo as it develops implantation competence. Total RNA from human ampullary oviducts in the early luteal versus follicular phases was isolated and hybridized to oligonucleotide arrays. The data, analysed by bioinformatic approaches, revealed that 650 genes were significantly down- and 683 genes were significantly up-regulated in the luteal phase. Quantitative real-time PCR, immunoblot analysis and immunohistochemistry confirmed selected gene expression and cellular protein localization. The data demonstrated down-regulation of genes involved in macrophage recruitment, immunomodulation and matrix degeneration and up-regulation of ion transport and secretions, as well as anti-angiogenic and early pregnancy recognition. Together, these data suggest a unique hormonally regulated environment during embryo development, maturation and transport through the human oviduct and provide insight into mechanisms influencing acquisition of implantation competence of the human embryo during its passage through the oviduct en route to the uterine endometrium.

Live cell imaging of the oviduct

In the oviduct, the integrity of oocyte and sperm transport, fertilization, and early embryonic ontogenesis is essential for successful reproduction. Up to now, most of the knowledge on oocyte and sperm transport, gamete interaction and embryonic development has in most cases been gained exclusively by in vitro studies. In addition, especially the mechanisms of gameto-maternal interaction and embryo-maternal communication in the oviduct are still unknown. Recent techniques of live cell imaging and digital videomicroscopy allow for the first time to provide actual new insights in the mechanisms of sperm transport, sperm storage, oocyte transport, fertilization, gameto-maternal interaction and embryo-maternal crosstalk under near in vivo conditions. Detailed knowledge of these important events in the oviduct is the prerequisite to develop new therapeutic concepts for subfertility and infertility and to increase the success rates of the actual techniques of assisted reproduction (ART). Additionally the effects of drugs and hormones used in ART can be effectively studied using a functional oviductal epithelium. The guidelines for live cell imaging in the oviduct presented here should enable researches to establish a functional digital analysis system which allows to study physiological and pathological events in the oviduct under near in vivo conditions.

Ciliary transport, gamete interaction, and effects of the early embryo in the oviduct: ex vivo analyses using a new digital videomicroscopic system in the cow

Using a digital videomicroscopic analysis system in the bovine, we showed that the mechanisms of transport caused by ciliary beating are distinctly different in ampulla and isthmus of the oviduct. The average particle transport speed (PTS) in the oviduct (mean, 133 microm/sec) does not differ in the cycle (metestrus) and during pregnancy after implantation, but it is locally modulated at the site of the embryo. Using videomicroscopy, we were able to document that after entering the ampulla, the cumulus-oocyte complex (COC) is not transported by ciliary beating down the oviduct, but firmly attaches to the ampullar epithelium. This attachment is mediated by the cumulus cells. However, when a COC is degenerated, it is floating in the oviductal lumen. As soon as a vital COC is in the ampulla, the sperm bound in the sperm reservoir of the ampullar isthmic junction leave the reservoir and hurry to the oocyte. When a sperm has penetrated the zona pellucida, the COC detaches and continues its migration. Quantitative measurements showed that the early embryo is able to locally downregulate PTS during its migration down the oviduct. It locally changes the pattern of vascularization and induces the formation of secretory cells. Our studies imply that the oviductal epithelium is able to select vital oocytes. The early embryo is able to induce the formation of secretory cells, modify vascularization, and downregulate speed of transport, thus creating the prerequisite for the first embryo-maternal communication in the oviduct.

Energy substrates in bovine oviduct and uterine fluid and blood plasma during the oestrous cycle

Up to 40 percent of cattle embryos die within 3 weeks of fertilization but there is little or no published information on the composition of the oviduct and uterine fluids essential for their survival during this time. We have measured the concentrations of the energy substrates, glucose, lactate, and pyruvate in cattle oviduct fluid on Days 0, 2, 4, and 6 and uterine fluid on Days 6, 8, and 14 of the oestrous cycle and corresponding blood samples. Oviduct and uterine fluids were collected in situ. Glucose concentrations in oviduct and uterine fluids were similar on all days and lower than in plasma (P < 0.05). Oviduct lactate concentration was up to eightfold higher than uterine or plasma concentration (P < 0.01). Oviduct pyruvate concentrations were similar on all days and lower than plasma concentrations on Days 0 and 2 (P < 0.005). Pyruvate concentrations were similar in the uterus and in plasma except on Day 14 when the concentration in plasma was higher (P < 0.05). There were no associations between systemic progesterone or oestradiol and glucose, lactate or pyruvate. There was a linear positive relationship (P < 0.001) between oviduct fluid secretion rate and oviduct glucose concentration and a linear negative relationship (P < 0.001) between oviduct fluid secretion rate and oviduct lactate, but no association between uterine fluid secretion rate and energy substrates. The different concentrations and associations between the energy substrates in oviduct and uterine fluids and blood plasma indicate a differential regulation of the secretion of these energy substrates by the oviduct and uterine epithelium.

Female reproductive tract fluids: composition, mechanism of formation and potential role in the developmental origins of health and disease

The oviduct and uterus provide the environments for the earliest stages of mammalian embryo development. However, little is known about the mechanisms that underlie the formation of oviduct and uterine fluids, or the extent to which the supply of nutrients via these reproductive tract tissues matches the nutrient requirements of early embryos. After reviewing our limited knowledge of these phenomena, a new experimental paradigm is proposed in which the epithelia lining the endosalpinx and endometrium are seen as the final components in a supply line that links maternal diet at one end and embryo uptake of nutrients at the other. When considered in this way, the oviduct and uterine epithelia become, for a few days, potentially the most critical maternal tissues in the establishment of a healthy pregnancy. In fulfilling this ‘gatekeeper’ role, female reproductive tract fluids have a key role in the ‘developmental origins of health and disease’ concept.

Amino acids in oviduct and uterine fluid and blood plasma during the estrous cycle in the bovine

Up to 40% of cattle embryos die within 3 weeks of fertilization while they are nutritionally dependent on the maternal environment provided by the oviduct and uterine fluids for their development and survival. Despite this dependence there is limited information on the composition of these fluids in cattle. Amino acids are essential for the normal growth and development of the early embryo, acting as precursors of proteins and nucleic acids and as energy sources, osmolytes and signaling molecules. The objective of this study was to measure and compare the amino acid concentrations of oviduct and uterine fluid and blood plasma on different days of the estrous cycle. Oviduct fluid was collected in situ from anaesthetised heifers on Days 0, 2, 3, 4 and 6 and uterine fluid on Days 6, 8 and 14 of the estrous cycle and the concentrations of 19 amino acids determined. Glycine was the most abundant amino acid in both oviduct and uterine fluid. However, the concentrations of many amino acids differed between oviduct and uterus and many were present at higher concentrations in oviduct and uterine fluid than in blood plasma. Oviduct fluid concentrations of amino acids were not affected by day of cycle in contrast to uterine fluid for which there was a day of cycle effect on most of the amino acids. These results provide novel information on the amino acid concentrations in the maternal environment of the early cattle embryo and could form the basis for devising improved media for the production of embryos in vitro.

Smoke from traditional commercial, harm reduction and research brand cigarettes impairs oviductal functioning in hamsters (Mesocricetus auratus) in vitro

BACKGROUND

Cigarette smoke from 2R1 research brand cigarettes and specific toxicants in smoke inhibit oviductal functioning. Our purpose was to test the hypothesis that smoke from commercial cigarettes, including harm reduction cigarettes, inhibits oviductal functioning and to measure the concentration of previously identified toxicants in smoke from research and commercial cigarettes.

METHODS

Mainstream (MS) and sidestream (SS) smoke solutions from two research, six traditional commercial and three harm reduction brands were tested in vitro using an oviductal assay that measures ciliary beat frequency, oocyte retrieval rate and smooth muscle contraction.

RESULTS

Generally, smoke from each brand of cigarette was inhibitory in the three oviductal bioassays. SS, the major component of environmental tobacco smoke, was usually more inhibitory than MS, the smoke inhaled by active smokers. Nine cigarette toxicants, previously shown to be highly inhibitory in the oviductal bioassays, were quantified in MS and SS. 4-Methylpyridine, which was inhibitory by itself in picomolar doses, was present in the highest concentration in MS and SS solutions from all brands tested. In general, toxicant concentrations were higher in SS than in MS solutions.

CONCLUSIONS

These data show that commercial brands of cigarettes, including harm reduction cigarettes, contain toxicants that inhibit biological processes in the oviduct and could affect reproductive outcomes.

Infection of human fallopian tube epithelial cells with Neisseria gonorrhoeae protects cells from tumor necrosis factor alpha-induced apoptosis

Following infection with Neisseria gonorrhoeae, bacteria may ascend into the Fallopian tubes (FT) and induce salpingitis, a major cause of infertility. In the FT, interactions between mucosal epithelial cells and gonococci are pivotal events in the pathogen's infection cycle and the inflammatory response. In the current study, primary FT epithelial cells were infected in vitro with different multiplicities of infection (MOI) of Pil+ Opa+ gonococci. Bacteria showed a dose-dependent association with cells and induced the secretion of tumor necrosis factor alpha (TNF-alpha). A significant finding was that gonococcal infection (MOI = 1) induced apoptosis in approximately 30% of cells, whereas increasing numbers of bacteria (MOI = 10 to 100) did not induce apoptosis. Apoptosis was observed in only 11% of cells with associated bacteria, whereas >84% of cells with no adherent bacteria were apoptotic. TNF-alpha was a key contributor to apoptosis, since (i) culture supernatants from cells infected with gonococci (MOI = 1) induced apoptosis in naïve cultures, suggesting that a soluble factor was responsible; (ii) gonococcal infection-induced apoptosis was inhibited with anti-TNF-alpha antibodies; and (iii) the addition of exogenous TNF-alpha induced apoptosis, which was inhibited by the presence of increasing numbers of bacteria (MOI = 10 to 100). These data suggest that TNF-alpha-mediated apoptosis of FT epithelial cells is likely a primary host defense mechanism to prevent pathogen colonization. However, epithelial cell-associated gonococci have evolved a mechanism to protect the cells from undergoing TNF-alpha-mediated apoptosis, and this modulation of the host innate response may contribute to establishment of infection. Understanding the antiapoptotic mechanisms used by Neisseria gonorrhoeae will inform the pathogenesis of salpingitis and could suggest new intervention strategies for prevention and treatment of the disease.

Dioxin exerts anti-estrogenic actions in a novel dioxin-responsive telomerase-immortalized epithelial cell line of the porcine oviduct (TERT-OPEC)

Oviduct epithelial cells are important for the nourishment and survival of ovulated oocytes and early embryos, and they respond to the steroid hormones estrogen and progesterone. Endocrine-disrupting polyhalogenated aromatic hydrocarbons (PHAH) are environmental toxins that act in part through the ligand-activated transcription factor arylhydrocarbon receptor (AhR; dioxin receptor), and exposure to PHAH has been shown to decrease fertility. To investigate effects of PHAHs on the oviduct epithelium as a potential target tissue of dioxin-type endocrine disruptors, we have established a novel telomerase-immortalized oviduct porcine epithelial cell line (TERT-OPEC). TERT-OPEC exhibited active telomerase and the immunoreactive epithelial marker cytokeratin but lacked the stromal marker vimentin. TERT-OPEC contained functional estrogen receptor (ER)-alpha and AhR, as determined by the detection of ER-alpha- and AhR-specific target molecules. Treatment of TERT-OPEC with the AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) resulted in a significant increase in the production of the cytochrome P-450 microsomal enzyme CYP1A1. Activated AhR caused a downregulation of ER nuclear protein fraction and significantly decreased ER-signaling in TERT-OPEC as determined by ERE-luciferase transient transfection assays. In summary, the TCDD-induced and AhR-mediated anti-estrogenic responses by TERT-OPEC suggest that PHAH affect the predominantly estrogen-dependent differentiation of the oviduct epithelium within the fallopian tube. This action then alters the local endocrine milieu, potentially resulting in a largely unexplored cause of impaired embryonic development and female infertility.

Successful use of oviduct epithelial cell coculture for in vitro production of viable red deer (Cervus elaphus) embryos

Techniques for in vitro production (IVP) of viable embryos have been thoroughly developed in several domestic species in view to improve breeding efficiency. When applied to wild life, these techniques may also help the maintenance of biodiversity through amplification of sparse animals offspring and facilitation of genetic material exchange. During the successive steps of IVP, i.e. oocyte in vitro maturation (IVM), fertilization (IVF) and early embryo development (IVD) to the blastocyst stage, gametes and embryos are faced with unusual environment, including oxidative stress, known to be detrimental to their survival. In the present study, starting from methods developed in domestic species, we have adapted IVP to produce viable red deer embryos. In a first experiment, cumulus cells were removed from in vitro matured oocytes either before or after IVF. The presence of cumulus cells during IVF did not affect final cleavage or development rates. In a second experiment, in vitro matured oocytes were fertilized in the presence of cumulus cells and cultured in SOFaaBSA medium alone or in the presence of ovine oviduct epithelial cell (oOEC) monolayer. Whereas, oviduct cells did not improve the cleavage rate, they significantly increased the rate of embryos reaching the blastocyst stage (from 3 to 25% of total oocytes). Ten blastocysts from oOEC coculture were transferred after freezing and thawing to five recipient hinds and gave rise to three pregnancies. The three pregnant hinds gave birth to three live and normal calves.

Smoking and reproduction: the oviduct as a target of cigarette smoke

The oviduct is an exquisitely designed organ that functions in picking-up ovulated oocytes, transporting gametes in opposite directions to the site of fertilization, providing a suitable environment for fertilization and early development, and transporting preimplantation embryos to the uterus. A variety of biological processes can be studied in oviducts making them an excellent model for toxicological studies. This review considers the role of the oviduct in oocyte pick-up and embryo transport and the evidence that chemicals in both mainstream and sidestream cigarette smoke impair these oviductal functions. Epidemiological data have repeatedly shown that women who smoke are at increased risk for a variety of reproductive problems, including ectopic pregnancy, delay to conception, and infertility. In vivo and in vitro studies indicate the oviduct is targeted by smoke components in a manner that could explain some of the epidemiological data. Comparisons between the toxicity of smoke from different types of cigarettes, including harm reduction cigarettes, are discussed, and the chemicals in smoke that impair oviductal functioning are reviewed.

Culture of early stage ovine embryos to blastocyst enhances survival rate after cryopreservation

The current study assessed both the effects of in vitro culture and developmental stage of early stage in vivo produced ovine embryos on their ability to survive cryopreservation. Early stage embryos (n=226) were recovered from the oviduct, at different days of the early luteal phase, at three different developmental stages: 2- to 4-cell, 5- to 8-cell and 9- to 12-cell. For each stage, half of the embryos were cultured to the blastocyst stage and frozen thereafter (CF), while the remainder was frozen just after recovery (EF). A third experimental group (BF; n=43) included blastocysts obtained from the uterus and frozen immediately after recovery. Embryo viability post-thawing was determined by assessing their rate of development to the hatched blastocyst stage following in vitro culture. Culture negatively affected embryo viability, since survival rate was higher in blastocysts obtained from the uterus than in those from culture (83.7% versus 66.1%; P<0.05); also the cryosurvival of cultured embryos was lower when the timing of blastocyst formation was extended (P<0.01). However, survival following freezing-thawing of early developmental stages was significantly lower when compared to viability of their counterparts cultured to the blastocyst stage (23.1% versus 66.1%, P<0.0001). In conclusion, our results indicate that, despite the deleterious effects of culture per se, the culture of early in vivo produced ovine embryos to the blastocyst stage prior to be frozen improves their survival after thawing.