Review: The epic journey of sperm through the female reproductive tract

Gestational Trophoblastic Disease: Complete versus Partial Hydatidiform Moles

Hydatidiform moles, including both complete and partial moles, constitute a subset of gestational trophoblastic diseases characterized by abnormal fertilization resulting in villous hydrops and trophoblastic hyperplasia with or without embryonic development. This involves chromosomal abnormalities, where one or two sperms fertilize an empty oocyte (complete hydatidiform mole (CHM); mostly 46,XX) or two sperms fertilize one oocyte (partial hydatidiform mole (PHM); mostly 69,XXY). Notably, recurrent occurrences are associated with abnormal genomic imprinting of maternal effect genes such as NLRP7 (chromosome 19q13.4) and KHDC3L (chromosome 6q1). Ongoing efforts to enhance identification methods have led to the identification of growth-specific markers, including p57 (cyclin-dependent kinase inhibitor 1C; CDKN1C), which shows intact nuclear expression in the villous cytotrophoblast and villous stromal cells in PHMs and loss of expression in CHMs. Treatment of hydatidiform moles includes dilation and curettage for uterine evacuation of the molar pregnancy followed by surveillance of human chorionic gonadotropin (HCG) levels to confirm disease resolution and rule out the development of any gestational trophoblastic neoplasia. In this review, we provide a synopsis of the existing literature on hydatidiform moles, their diagnosis, histopathologic features, and management.

Uterotubal junction of the bovine (Bos taurus) versus the dromedary camel (Camelus dromedarius): Histology and histomorphometry

This study aims to conduct a comparative analysis of the uterotubal junction in two distinct mammalian species, the bovine (Bos taurus) and the dromedary camel (Camelus dromedarius), focusing on histological and histomorphometric parameters. Uterotubal junction (UTJ) was dissected from 8 cows and 12 camels with dominant follicles, and processed for H&E staining for histology, and histomorphometry examination. The results showed that the camel uterotubal junction papillae (UTJP) existed only in camels and was completely absent in cattle. Histologically, the cow UTJ appears with a star-shaped lumen, and the mucosa is lined by a simple columnar epithelium with ciliated and non-ciliated cells. Superficial (SG) and deep glands (DG) were abundant in the submucosa. Camel UTJP is a conical structure, it has a pale yellowish colour, 0.5 ± 0.2 cm height, and 0.3 ± 0.1 cm width, and it has a distinct sphincter at the tip towards the uterine lumen. In the camel UTJP, the lumen is wider, and the mucosa showed large multiple folds lined with ciliated and non-ciliated cells in a pseudostratified columnar epithelium. The submucosa showed no mucosal glands. Lumen area, lumen epithelial height, luminal epithelial density, the thickness of the muscular layer, number of folds, fold height, epithelial height, fold area and epithelial perimeter were higher in camel UTJP (p < .001) than cow UTJ, while the total endosalpinx area and glandular epithelial density were lower in camel UTJP (p < .001) than in cow UTJ. In conclusion, this study elucidates potential variations in the uterotubal junction between bovines and dromedary camels, providing valuable insights into their reproductive adaptations. The epithelial lining, absence of glands and the thick layer of tunica muscularis might indicate that camel UTJP could play a mechanical role in selecting spermatozoa and assisting the hatching of blastocysts during their passage into the uterus.

An updated study of the relationship between bacterial infections and women's immune system, focusing on bacterial compositions with successful pregnancy

Genital tract infections can cause a variety of harmful health outcomes, including endometritis, bacterial vaginosis, and pelvic inflammatory disease, in addition to infertility. Anaerobic bacteria, such as Gardnerella vaginalis, Megasphaera spp., and Atopobium vaginae, are more commonly identified in cases of bacterial vaginosis than lactobacilli. It is unknown how the microorganisms that cause pelvic inflammatory diseases and endometritis enter the uterus. Both prospective and retrospective research have connected pelvic inflammatory disorders, chronic endometritis, and bacterial vaginosis to infertility. Similar to bacterial vaginosis, endometritis-related infertility is probably caused by a variety of factors, such as inflammation, immune system recognition of sperm antigens, bacterial toxins, and a higher risk of STDs. Preconception care for symptomatic women may include diagnosing and treating pelvic inflammatory disease, chronic endometritis, and bacterial vaginosis before conception to optimize the results of both natural and assisted reproduction.

Triblock Glycopolymers with Two 10-mer Blocks of Activating Sugars Enhance the Activation of Acrosomal Exocytosis in Mouse Sperm

Carbohydrate recognition is imperative for the induction of sperm acrosomal exocytosis (AE), an essential phenomenon in mammalian fertilization. In mouse sperm, polynorbornene 100-mers displaying fucose or mannose moieties were effective at inducing AE. In contrast, glycopolymers exhibiting glucose sugars resulted in no AE activation. To further elucidate the role of ligand density on the activation of AE in mouse sperm, a triple-stain flow cytometry assay was employed to determine the efficacy of polynorbornene block copolymers with barbell-like sequences as initiators of AE. Triblock (ABA or ABC) copolymers were synthesized by ring-opening metathesis polymerization (ROMP) with one or two activating sugars, mannose or fucose, and one nonactivating sugar, glucose. The active ligand fractions in the polymers varied from 10, 20, or 40%. Simultaneously, random copolymers comprising 20% activating ligands were prepared to confirm the importance of ligand positionality in AE activation in mouse sperm. Polynorbornene 100-mers possessing two 10-mer blocks of activating sugars were the most effective copolymers at inducing AE with levels of AE comparable to their homopolymer counterparts and more effective than their random analogues. Small-angle X-ray scattering (SAXS) was then performed to verify that there were no differences in the conformations of the glycopolymers contributing to their varying AE activity. SAXS data analysis confirmed that all of the glycopolymers assumed semiflexible cylindrical structures with similar radii and Kuhn lengths. These findings suggest that the overall ligand density of the sugar moieties in the polymer is less important than the positionality of short blocks of high-density ligands for AE activation in mouse sperm.

Microfluidics as an emerging paradigm for assisted reproductive technology: A sperm separation perspective

Millions of people are subject to infertility worldwide and one in every six people, regardless of gender, experiences infertility at some period in their life, according to the World Health Organization. Assisted reproductive technologies are defined as a set of procedures that can address the infertility issue among couples, culminating in the alleviation of the condition. However, the costly conventional procedures of assisted reproduction and the inherent vagaries of the processes involved represent a setback for its successful implementation. Microfluidics, an emerging tool for processing low-volume samples, have recently started to play a role in infertility diagnosis and treatment. Given its host of benefits, including manipulating cells at the microscale, repeatability, automation, and superior biocompatibility, microfluidics have been adopted for various procedures in assisted reproduction, ranging from sperm sorting and analysis to more advanced processes such as IVF-on-a-chip. In this review, we try to adopt a more holistic approach and cover different uses of microfluidics for a variety of applications, specifically aimed at sperm separation and analysis. We present various sperm separation microfluidic techniques, categorized as natural and non-natural methods. A few of the recent developments in on-chip fertilization are also discussed.

Sperm binding to oviduct epithelial spheroids varies among males and ejaculates but not among females in pigs

The elimination of ejaculates and males with low fertility despite good sperm motility and morphology is crucial to maintain high pregnancy rates after artificial insemination (AI) in farm animals. The ability of sperm to survive in the female tract is particularly crucial in pigs due to the large variation in the timing between AI and ovulation and the high number of oocytes to fertilise. The objective of this study was to characterise a new in vitro model of oviduct sperm reservoir using porcine oviduct epithelial spheroids (OES) and to assess the variability in sperm binding to OES among gilts, boars and their ejaculates. Isthmic mucosa fragments were collected from gilt oviducts at a slaughterhouse, and after 48 h of culture, the OES that had spontaneously formed were sorted according to their vesicle shape and size (150-200 μm in diameter) for characterisation and sperm binding assays. The OES contained viable, cytokeratin-positive and vimentin-negative cells, of which 36.4 ± 2.0% were multiciliated. The average proportion of multiciliated cells per OES did not change among culture replicates. After co-incubation with boar fresh semen, only sperm of normal morphology were found to bind, by their head, to cilia of OES. The density of sperm bound to the OES surface increased linearly with sperm concentration. The bound sperm density on OES was used to assess the binding capacity of fresh ejaculates collected from Pietrain boars. For a given ejaculate, the bound sperm density did not vary among pools of OES female donors. The analysis of five successive ejaculates from nine boars indicated significant differences in bound sperm densities on the OES among individual boars and their ejaculates (P < 0.01). There was no correlation between the sperm bound density and sperm parameters measured by computer-assisted sperm analysis or the initial dilution of the ejaculate. In conclusion, the OES characterised in this study offered physiological conditions to study sperm binding to the isthmic reservoir and evidenced that sperm from different ejaculates and different boars vary in their ability to bind to these oviduct spheroids despite homogeneous motility and morphology.

Transcriptomics analysis of the bovine endometrium during the perioestrus period

During the oestrous cycle, the bovine endometrium undergoes morphological and functional changes, which are regulated by alterations in the levels of oestrogen and progesterone and consequent changes in gene expression. To clarify these changes before and after oestrus, RNA-seq was used to profile the transcriptome of oestrus-synchronized beef heifers. Endometrial samples were collected from 29 animals, which were slaughtered in six groups beginning 12 h after the withdrawal of intravaginal progesterone releasing devices until seven days post-oestrus onset (luteal phase). The groups represented proestrus, early oestrus, metoestrus and early dioestrus (luteal phase). Changes in gene expression were estimated relative to gene expression at oestrus. Ingenuity Pathway Analysis (IPA) was used to identify canonical pathways and functional processes of biological importance. A total of 5,845 differentially expressed genes (DEGs) were identified. The lowest number of DEGs was observed at the 12 h post-oestrus time point, whereas the greatest number was observed at Day 7 post-oestrus onset (luteal phase). A total of 2,748 DEGs at this time point did not overlap with any other time points. Prior to oestrus, Neurological disease and Organismal injury and abnormalities appeared among the top IPA diseases and functions categories, with upregulation of genes involved in neurogenesis. Lipid metabolism was upregulated before oestrus and downregulated at 48h post-oestrus, at which point an upregulation of immune-related pathways was observed. In contrast, in the luteal phase the Lipid metabolism and Small molecule biochemistry pathways were upregulated.

Multi-scale structures of the mammalian radial spoke and divergence of axonemal complexes in ependymal cilia

Radial spokes (RS) transmit mechanochemical signals between the central pair (CP) and axonemal dynein arms to coordinate ciliary motility. Atomic-resolution structures of metazoan RS and structures of axonemal complexes in ependymal cilia, whose rhythmic beating drives the circulation of cerebrospinal fluid, however, remain obscure. Here, we present near-atomic resolution cryo-EM structures of mouse RS head-neck complex in both monomer and dimer forms and reveal the intrinsic flexibility of the dimer. We also map the genetic mutations related to primary ciliary dyskinesia and asthenospermia on the head-neck complex. Moreover, we present the cryo-ET and sub-tomogram averaging map of mouse ependymal cilia and build the models for RS1-3, IDAs, and N-DRC. Contrary to the conserved RS structure, our cryo-ET map reveals the lack of IDA-b/c/e and the absence of Tektin filaments within the A-tubule of doublet microtubules in ependymal cilia compared with mammalian respiratory cilia and sperm flagella, further exemplifying the structural diversity of mammalian motile cilia. Our findings shed light on the stepwise mammalian RS assembly mechanism, the coordinated rigid and elastic RS-CP interaction modes beneficial for the regulation of asymmetric ciliary beating, and also facilitate understanding on the etiology of ciliary dyskinesia-related ciliopathies and on the ependymal cilia in the development of hydrocephalus.

Evaluation of sperm and hormonal assessments in Wagyu, Nellore, and Angus bulls

Wagyu bulls are known to have a highly exacerbated libido, as shown by the intense sexual interest of young calves. Therefore we believe that Wagyu male animals have specialized Sertoli and Leydig cells that are directly involved with the sexual precocity in this breed as mature bulls have a small scrotal circumference. This study aimed to evaluate whether there were differences in the hormone and sperm characteristics of Wagyu bulls compared with the same characteristics of subspecies Bos indicus and Bos taurus sires. Frozen-thawed semen from Wagyu, Nellore, and Angus sires were analyzed for sperm kinetics (computer-assisted sperm analysis), plasma membrane integrity, chromatin integrity, acrosome status, mitochondrial activity, lipid peroxidation and hormone [luteinizing hormone (LH) and testosterone] serum concentration. The results showed that Wagyu had lower total motility and an increased number of sperm with no motility when compared with Nellore and Angus bulls. Wagyu breed did not differ from those breeds when considering plasma and acrosome membranes integrity, mitochondrial potential, chromatin resistance, sperm lipid peroxidation or hormone (LH and testosterone) concentrations. We concluded that Wagyu sires had lower total motility when compared with Nellore and Angus bulls. Wagyu breed did not differ from these breeds when considering plasma and acrosome membranes integrity, mitochondrial potential, chromatin resistance, sperm lipid peroxidation, or hormone (LH and testosterone) concentrations.

An oviduct glycan increases sperm lifespan by diminishing the production of ubiquinone and reactive oxygen species†

Sperm storage by females after mating for species-dependent periods is used widely among animals with internal fertilization to allow asynchrony between mating and ovulation. Many mammals store sperm in the lower oviduct where specific glycans on oviduct epithelial cells retain sperm to form a reservoir. Binding to oviduct cells suppresses sperm intracellular Ca2+ and increases sperm longevity. We investigated the mechanisms by which a specific oviduct glycan, 3-O-sulfated Lewis X trisaccharide (suLeX), prolongs the lifespan of porcine sperm. Using targeted metabolomics, we found that binding to suLeX diminishes the abundance of 4-hydroxybenzoic acid, the precursor to ubiquinone (also known as Coenzyme Q), 30 min after addition. Ubiquinone functions as an electron acceptor in the electron transport chain (ETC). 3-O-sulfated Lewis X trisaccharide also suppressed the formation of fumarate. A component of the citric acid cycle, fumarate is synthesized by succinate-coenzyme Q reductase, which employs ubiquinone and is also known as Complex II in the ETC. Consistent with the reduced activity of the ETC, the production of harmful reactive oxygen species (ROS) was diminished. The enhanced sperm lifespan in the oviduct may be because of suppressed ROS production because high ROS concentrations have toxic effects on sperm.

Bull Semen Obtained on Beef Farms by Electroejaculation: Sperm Quality in the First Two Hours of Storing with Different Extenders and Holding Temperatures

Sperm quality decreases over time, so bull semen may need to be preserved after field collection. However, the effect of handling such semen samples from commercial farms and placing them in very short-term storage has not been elucidated. Therefore, ejaculate from 25 bulls from 1 dairy and 14 beef cattle farms were collected under farm conditions and evaluated for semen quality during the first two hours after collection. Two commercial extenders (AndroMed^® and BIOXcell^®) and two different storage temperatures (5 °C and room temperature) were used to evaluate the influence on semen quality and sperm kinetics in ejaculates grouped into three evaluation times, based on time since collection (Time 1: <75 min, n = 7; Time 2: 75-105 min, n = 11; and Time 3: 105-120 min, n = 7). Classical semen parameters, sperm motion kinetics by CASA and colony-forming units were assessed. The differences between both extenders in curvilinear and straight-line velocities (VCL and VSL) for the different time groups (Time 2 and Time 3) were statistically significant for p < 0.05. AndroMed^® showed lower VSL, straightness and linearity in sperm compared to BIOXcell^® (p < 0.05). In conclusion, AndroMed^® induced more curvilinear movement, while BIOXcell^® stimulated straighter motility.

Sperm selection by the oviduct: perspectives for male fertility and assisted reproductive technologies†

The contribution of sperm to embryogenesis is gaining attention with up to 50% of infertility cases being attributed to a paternal factor. The traditional methods used in assisted reproductive technologies for selecting and assessing sperm quality are mainly based on motility and viability parameters. However, other sperm characteristics, including deoxyribonucleic acid integrity, have major consequences for successful live birth. In natural reproduction, sperm navigate the male and female reproductive tract to reach and fertilize the egg. During transport, sperm encounter many obstacles that dramatically reduce the number arriving at the fertilization site. In humans, the number of sperm is reduced from tens of millions in the ejaculate to hundreds in the Fallopian tube (oviduct). Whether this sperm population has higher fertilization potential is not fully understood, but several studies in animals indicate that many defective sperm do not advance to the site of fertilization. Moreover, the oviduct plays a key role in fertility by modulating sperm transport, viability, and maturation, providing sperm that are ready to fertilize at the appropriate time. Here we present evidence of sperm selection by the oviduct with emphasis on the mechanisms of selection and the sperm characteristics selected. Considering the sperm parameters that are essential for healthy embryonic development, we discuss the use of novel in vitro sperm selection methods that mimic physiological conditions. We propose that insight gained from understanding how the oviduct selects sperm can be translated to assisted reproductive technologies to yield high fertilization, embryonic development, and pregnancy rates.

An oviduct glycan increases sperm lifespan by diminishing ubiquinone and production of reactive oxygen species

Sperm storage by females after mating for species-dependent periods is used widely among animals with internal fertilization to allow asynchrony between mating and ovulation. Many mammals store sperm in the lower oviduct where specific glycans on epithelial cells retain sperm to form a reservoir. Binding to oviduct cells suppresses sperm intracellular Ca 2+ and increases sperm longevity. We investigated the mechanisms by which a specific oviduct glycan, 3-O-sulfated Lewis X trisaccharide (suLe X ), prolongs the lifespan of porcine sperm. Using targeted metabolomics, we report that binding to suLe X diminishes the abundance of the precursor to ubiquinone and suppresses formation of fumarate, a specific citric acid cycle component, diminishing the activity of the electron transport chain and reducing the production of harmful reactive oxygen species (ROS). The enhanced sperm lifespan in the oviduct may be due to suppressed ROS production as many reports have demonstrated toxic effects of high ROS concentrations on sperm.

Optical coherence tomography for dynamic investigation of mammalian reproductive processes

The biological events associated with mammalian reproductive processes are highly dynamic and tightly regulated by molecular, genetic, and biomechanical factors. Implementation of live imaging in reproductive research is vital for the advancement of our understanding of normal reproductive physiology and for improving the management of reproductive disorders. Optical coherence tomography (OCT) is emerging as a promising tool for dynamic volumetric imaging of various reproductive processes in mice and other animal models. In this review, we summarize recent studies employing OCT-based approaches toward the investigation of reproductive processes in both, males and females. We describe how OCT can be applied to study structural features of the male reproductive system and sperm transport through the male reproductive tract. We review OCT applications for in vitro and dynamic in vivo imaging of the female reproductive system, staging and tracking of oocytes and embryos, and investigations of the oocyte/embryo transport through the oviduct. We describe how the functional OCT approach can be applied to the analysis of cilia dynamics within the male and female reproductive systems. We also discuss the areas of research, where OCT could find potential applications to progress our understanding of normal reproductive physiology and reproductive disorders.

Pharmacological perturbation of peroxisome-proliferator-activated receptor gamma alters motility and mitochondrial function of bovine sperm

BACKGROUND

Sperm transit through the female reproductive relies upon maintenance of sperm motility. Peroxisome-proliferator-activated receptor gamma (PPARγ) is a ligand-activated nuclear transcription factor with roles in glucose metabolism and reproductive processes including placental function. PPARγ roles in the mammalian postejaculatory sperm function are incompletely defined.

OBJECTIVES

Determine expression, localization, and functions of PPARγ in postejaculatory bovine sperm.

MATERIALS AND METHODS

Frozen-thawed bovine sperm from three to four different bulls were pooled and subjected to immunofluorescence and western blot for detection and localization of PPARγ. Functions in sperm energetics were explored through the addition of pharmacological inhibition (GW; GW9662) and activation (Ros; Rosiglitazone) in the culture medium at 0 and 24 h under non-capacitating conditions. Samples were analyzed for sperm kinematics (CASA) and mitochondrial membrane potential (MMP; JC-1 fluorophore).

RESULTS

PPARγ was detected in bovine sperm and co-localized to the acrosome with re-localization to the equatorial region in acrosome-compromised sperm. The addition of Ros 50 µM for 24 h maintained superior total and progressive motility of sperm compared to vehicle control (VC-DMSO 0.01%). The PPARγ antagonist GW 1 µM was detrimental to both total and progressive motility. A challenge experiment (Ros + GW) partially rescued total and progressive motility phenotypes observed with GW incubation. GW-treated samples had a lower number of sperm with high MMP at 24 h compared to Ros or VC. The negative GW MMP phenotype was reversed with the addition of Ros + GW. Likewise, GW-treated samples had more sperm with low MMP compared to VC and Ros, and this phenotype was partially restored with Ros + GW.

CONCLUSION

PPARγ is expressed in post-ejaculatory bovine sperm with regulatory roles in sperm motility and MMP. These findings implicate PPARγ as a novel regulator of postejaculatory mammalian sperm energetics through non-canonical signaling mechanisms.

Fertility of Holstein cows and heifers submitted to timed artificial insemination and receiving one or two doses (12 h apart) of semen

The objective of this retrospective study was to assess the effect of receiving a single (n = 50,285) or double (n = 4392) artificial insemination (AI), 12 h apart, within a timed artificial insemination protocol on pregnancy per AI (P/AI) in nulliparous heifers (inseminated with either sex-sorted or conventional semen) and pluriparous Holstein cows in a commercial dairy herd. Also, this study aimed to investigate the relationship between temperature-humidity index (THI) and time of the first AI and fertility. Fertility of cows receiving two AI with normothermia (THI <68) was higher (p < .05) than cows receiving a single AI (42.9% vs. 36.4%). P/AI of cows receiving two AI with severe heat stress (THI >85) was higher (p < .05) than cows receiving a single AI (21.0% vs. 12.6%). Regardless of heat stress conditions, applying the first AI in the morning increased (p < .05) P/AI in cows with double AI than in cows whose first AI occurred in the afternoon (38.4 vs. 33.3%). With moderate heat stress, and sexed-sorted semen, P/AI to timed AI was higher (65.0 vs. 51.9%; p < .05) in heifers receiving double AI than those serviced once. It was concluded that double AI, 12 h apart, enhanced fertility at timed AI than herd mates with a single AI, particularly with heat stress at breeding.

Motility Assessment of Ram Spermatozoa

For successful fertilisation to occur, spermatozoa need to successfully migrate through the female reproductive tract and penetrate the oocyte. Predictably, poor sperm motility has been associated with low rates of fertilisation in many mammalian species, including the ram. As such, motility is one of the most important parameters used for in vitro evaluation of ram sperm quality and function. This review aims to outline the mechanical and energetic processes which underpin sperm motility, describe changes in motility which occur as a result of differences in sperm structure and the surrounding microenvironment, and assess the effectiveness of the various methods used to assess sperm motility in rams. Methods of subjective motility estimation are convenient, inexpensive methods widely used in the livestock industries, however, the subjective nature of these methods can make them unreliable. Computer-assisted sperm analysis (CASA) technology accurately and objectively measures sperm motility via two-dimensional tracing of sperm head motion, making it a popular method for sperm quality assurance in domesticated animal production laboratories. Newly developed methods of motility assessment including flagellar tracing, three-dimensional sperm tracing, in vivo motility assessment, and molecular assays which quantify motility-associated biomarkers, enable analysis of a new range of sperm motion parameters with the potential to reveal new mechanistic insights and improve ram semen assessment. Experimental application of these technologies is required to fully understand their potential to improve semen quality assessment and prediction of reproductive success in ovine artificial breeding programs.

Interaction of sperm cells with the female reproductive tract in cattle: Focus on neutrophil extracellular trap formation

After insemination of cows, either naturally or artificially, the deposition of semen into the vagina or uterus results in an immune reaction which is based on polymorphonuclear neutrophil activity. Sperm must be resistant to immune system actions of the female for an adequate time to allow fertilization to occur. Neutrophils, however, either directly phagocytize sperm through cell-cell attachment or entrap sperm cells in neutrophil extracellular traps (NETs), structures consisting of neutrophil nuclear DNA and associated proteins. In this review article, the interaction of neutrophils and sperm cells in t cattle will be described, with a special focus on the formation of neutrophil extracellular traps (NETs).

Prolonging the time of semen deposition increases the pregnancy rates of ewes subjected to fixed time cervical insemination during the breeding season

The main limiting factor of artificial cervical insemination in ewes is the long and narrow fibrous cervical canal, which impedes the transport of spermatozoa and leads to lower pregnancy rates. The hypothesis that prolonging the time of semen deposition during ovine cervical insemination can increase pregnancy rates was investigated in this study. Estrus was synchronized in 150 multiparous Ujimqin ewes using a polyurethane intravaginal sponge impregnated with 45 mg of flurogestone acetate. The sponge was left in the vagina for 12 days followed by an injection of 330 IU of eCG at sponge removal. After exclusion of two ewes due to sponge loss, the remaining 148 ewes were divided into the Treatment group (n = 75) and the Control group (n = 73). Each ewe was inseminated once between 56 h to 60 h after the removal of sponges, using a new type of insemination device containing 0.25 ml of diluted semen. Semen was collected from eight Black Suffolk rams and all the ejaculates were pooled and diluted in ultra-high temperature-treated commercial skimmed milk. The time of semen deposition was prolonged to 60 s in the Treatment group, while ewes were given a traditional insemination in the Control group. Pregnancy status was determined by transabdominal ultrasound examination 45 days after insemination. Lambing performance was calculated after all the ewes had delivered. Significant differences were observed between the Treatment group and the Control group in terms of the pregnancy rate and the fecundity rate (73.3% and 93.3% vs 56.2% and 71.2%, p < 0.05 and p < 0.01, respectively). In conclusion, prolonging the time of semen deposition significantly increased pregnancy and fecundity rates in estrus-synchronized Ujimqin ewes subjected to fixed time cervical insemination.

Progesterone-Induced Sperm Release from the Oviduct Sperm Reservoir

In mammalian females, after sperm are deposited in the reproductive tract, a fraction of sperm migrates to the lower oviduct (isthmus) and forms a sperm storage site known as the functional sperm reservoir. The interactions between sperm membrane proteins and oviduct epithelial cells facilitate sperm binding to the oviductal epithelium and retention in the reservoir. Sperm are bound by glycans that contain specific motifs present on isthmic epithelial cells. Capacitated sperm are released from the reservoir and travel further in the oviduct to the ampulla where fertilization occurs. For decades, researchers have been studying the molecules and mechanisms of sperm release from the oviductal sperm reservoir. However, it is still not clear if the release of sperm is triggered by changes in sperm, oviduct cells, oviduct fluid, or a combination of these. While there is a possibility that more than one of these events are involved in the release of sperm from the reservoir, one activator of sperm release has the largest accumulation of supporting evidence. This mechanism involves the steroid hormone, progesterone, as a signal that induces the release of sperm from the reservoir. This review gathers and synthesizes evidence for the role of progesterone in inducing sperm release from the oviduct functional sperm reservoir.

Pre-Treatment of Swine Oviductal Epithelial Cells with Progesterone Increases the Sperm Fertilizing Ability in an IVF Model

Mammalian spermatozoa are infertile immediately after ejaculation and need to undergo a functional modification, called capacitation, in order to acquire their fertilizing ability. Since oviductal epithelial cells (SOECs) and progesterone (P4) are two major modulators of capacitation, here we investigated their impact on sperm functionality by using an IVF swine model. To that, we treated SOECs with P4 at 10, 100, and 1000 ng/mL before the coincubation with spermatozoa, thus finding that P4 at 100 ng/mL does not interfere with the cytoskeleton dynamics nor the cells’ doubling time, but it promotes the sperm capacitation by increasing the number of spermatozoa per polyspermic oocyte (p < 0.05). Moreover, we found that SOECs pre-treatment with P4 100 ng/mL is able to promote an increase in the sperm fertilizing ability, without needing the hormone addition at the time of fertilization. Our results are probably due to the downregulation in the expression of OVGP1, SPP1 and DMBT1 genes, confirming an increase in the dynamism of our system compared to the classic IVF protocols. The results obtained are intended to contribute to the development of more physiological and efficient IVF systems.

Amino Acid Transport and Metabolism Regulate Early Embryo Development: Species Differences, Clinical Significance, and Evolutionary Implications

In this review we discuss the beneficial effects of amino acid transport and metabolism on pre- and peri-implantation embryo development, and we consider how disturbances in these processes lead to undesirable health outcomes in adults. Proline, glutamine, glycine, and methionine transport each foster cleavage-stage development, whereas leucine uptake by blastocysts via transport system B^0,+ promotes the development of trophoblast motility and the penetration of the uterine epithelium in mammalian species exhibiting invasive implantation. (Amino acid transport systems and transporters, such as B^0,+, are often oddly named. The reader is urged to focus on the transporters’ functions, not their names.) B^0,+ also accumulates leucine and other amino acids in oocytes of species with noninvasive implantation, thus helping them to produce proteins to support later development. This difference in the timing of the expression of system B^0,+ is termed heterochrony—a process employed in evolution. Disturbances in leucine uptake via system B^0,+ in blastocysts appear to alter the subsequent development of embryos, fetuses, and placentae, with undesirable consequences for offspring. These consequences may include greater adiposity, cardiovascular dysfunction, hypertension, neural abnormalities, and altered bone growth in adults. Similarly, alterations in amino acid transport and metabolism in pluripotent cells in the blastocyst inner cell mass likely lead to epigenetic DNA and histone modifications that produce unwanted transgenerational health outcomes. Such outcomes might be avoided if we learn more about the mechanisms of these effects.

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

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

Immunological response of fallopian tube epithelial cells to spermatozoa through modulating cytokines and chemokines

BACKGROUND

Spermatozoa interactions with fallopian tubes may influence fertilization. The purpose was to investigate cytokines, chemokines and growth factors expression from human fallopian tube epithelial cells (OE-E6/E7) exposed to spermatozoa.

METHODS

Fresh semen samples were obtained from 10 healthy normozoospermic men. Sperms were prepared and co-cultured with OE-E6/E7. The cell line without spermatozoa was considered as the control group. Afterwards, Expression of 84 cytokines from OE-E6/E7 cell line in the presence and absence of spermatozoa were measured using PCR-array. Quantitative PCR was performed on seven genes to confirm the results of PCR-array analysis. Differentially expressed genes were subjected to www.geneontology.org and www.pantherdb.org to perform GO enrichment and panther pathway analysis. The concentration of IL-8, IL-10, IL-1B and BMP-4 in culture medium were analyzed by ELISA.

RESULTS

Sperm interaction with the epithelial cells resulted in a significant increase in expression of TGF-β2, BMP-4, IL-10, IL-9, and CD40LG markers. Moreover, expression of IL-16, IL-17F, SPP-1, CXCL-13, MSTN, IL-1A, IL-1B, IL-8, BMP-7, CSF-2, CSF-3, VEGF-A, OSM, LTA, TNF, TNFRSF11B, TNFSF11, CCL-11, CCL-20, CCL-24, CCL-3, CCL-8, CX3CL1 and CXCL-9 were considerably reduced in presence of spermatozoa. Panther pathway analysis discovered 3 pathways for upregulated genes including gonadotropin-releasing hormone receptor, TGF-beta and interleukin signaling pathways. Furthermore, 9 pathways were detected for down-regulated genes. Inflammation signaling pathway which is mediated by chemokine and cytokine contains the most number of genes.

CONCLUSION

This study indicates that sperm modifies expression of cytokines, chemokines and growth factors from OE-E6/E7. Moreover, altered genes expression are toward higher survival chance of the spermatozoa.

Vaginal neutrophils eliminate sperm by trogocytosis

STUDY QUESTION

What is the vaginal polymorphonuclear (PMN) spermicidal mechanism to reduce the excess of sperm?

SUMMARY ANSWER

We show that PMNs are very efficient at killing sperm by a trogocytosis-dependent spermicidal activity independent of neutrophil extracellular traps (NETs).

WHAT IS KNOWN ALREADY

Trogocytosis has been described as an active membrane exchange between immune cells with a regulatory purpose. Recently, trogocytosis has been reported as a mechanism which PMNs use to kill tumour cells or Trichomonas vaginalis.

STUDY DESIGN, SIZE, DURATION

We used in vivo murine models and human ex vivo sperm and PMNs to investigate the early PMN-sperm response.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We set up a live/dead sperm detection system in the presence of PMNs to investigate in vivo and ex vivo PMN-spermicidal activity by confocal microscopy, flow cytometry and computer-assisted sperm analysis (SCA).

MAIN RESULTS AND THE ROLE OF CHANCE

We revealed that PMNs are highly efficient at killing sperm by way of a NETs-independent, contact-dependent and serine proteases-dependent engulfment mechanism. PMNs 'bite' sperm and quickly reduce sperm motility (within 5 min) and viability (within 20 min) after contact.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This study was conducted using murine models and healthy human blood PMNs; whether it is relevant to human vaginal PMNs or to cases of infertility is unknown.

WIDER IMPLICATIONS OF THE FINDINGS

Vaginal PMNs attack and immobilize excess sperm in the vagina by trogocytosis because sperm are exogenous and may carry pathogens. Furthermore, this mechanism of sperm regulation has low mucosal impact and avoids an exacerbated inflammatory response that could lead to mucosal damage or infertility.

STUDY FUNDING/COMPETING INTEREST(S)

This work was partially supported by Ministry of Economy and Competitiveness ISCIII-FIS grants, PI16/00050, and PI19/00078, co-financed by ERDF (FEDER) Funds from the European Commission, 'A way of making Europe' and IiSGM intramural grant II-PI-MRC-2017. M.R. holds a Miguel Servet II contract (CPII14/00009). M.C.L. holds IiSGM intramural contract. There are no competing interests.

Role and Modulation of TRPV1 in Mammalian Spermatozoa: An Updated Review

Based on the abundance of scientific publications, the polymodal sensor TRPV1 is known as one of the most studied proteins within the TRP channel family. This receptor has been found in numerous cell types from different species as well as in spermatozoa. The present review is focused on analyzing the role played by this important channel in the post-ejaculatory life of spermatozoa, where it has been described to be involved in events such as capacitation, acrosome reaction, calcium trafficking, sperm migration, and fertilization. By performing an exhaustive bibliographic search, this review gathers, for the first time, all the modulators of the TRPV1 function that, to our knowledge, were described to date in different species and cell types. Moreover, all those modulators with a relationship with the reproductive process, either found in the female tract, seminal plasma, or spermatozoa, are presented here. Since the sperm migration through the female reproductive tract is one of the most intriguing and less understood events of the fertilization process, in the present work, chemotaxis, thermotaxis, and rheotaxis guiding mechanisms and their relationship with TRPV1 receptor are deeply analyzed, hypothesizing its (in)direct participation during the sperm migration. Last, TRPV1 is presented as a pharmacological target, with a special focus on humans and some pathologies in mammals strictly related to the male reproductive system.

Effects of In Vitro Interactions of Oviduct Epithelial Cells with Frozen-Thawed Stallion Spermatozoa on Their Motility, Viability and Capacitation Status

Simple Summary

The use of assisted reproductive techniques, which involve the manipulation of sperm and oocytes in the laboratory, support owner production of valuable animals’ offspring. However, several limitations remain underlining the need to further optimize existing protocols as well as to develop new strategies. For example, the required conditions to make equine spermatozoa competent to fertilize an oocyte in vitro (IVF) have not been established. Therefore, our initial goal was to optimize different conditions associated with frozen equine sperm manipulations in order to improve their quality. We observed that simple factors such as sample concentration, incubation period and centrifugation time affect the sperm motility. Since in vivo fertilization involves the interaction between spermatozoa and epithelial cells in the mare’s oviductal tract, our next goal was to mimic this environment by establishing primary cultures of oviductal cells. Using this in vitro system, we were able to select a sperm population capable of fertilization. In short, this study provides a novel protocol that improves the yield of fertilization-capable sperm obtained from equine frozen spermatozoa.

Abstract

Cryopreservation by negatively affecting sperm quality decreases the efficiency of assisted reproduction techniques (ARTs). Thus, we first evaluated sperm motility at different conditions for the manipulation of equine cryopreserved spermatozoa. Higher motility was observed when spermatozoa were incubated for 30 min at 30 × 10⁶/mL compared to lower concentrations (p < 0.05) and when a short centrifugation at 200× g was performed (p < 0.05). Moreover, because sperm suitable for oocyte fertilization is released from oviduct epithelial cells (OECs), in response to the capacitation process, we established an in vitro OEC culture model to select a sperm population with potential fertilizing capacity in this species. We demonstrated E-cadherin and cytokeratin expression in cultures of OECs obtained. When sperm–OEC cocultures were performed, the attached spermatozoa were motile and presented an intact acrosome, suggesting a selection by the oviductal model. When co-cultures were incubated in capacitating conditions a greater number of alive (p < 0.05), capacitated (p < 0.05), with progressive motility (p < 0.05) and with the intact acrosome sperm population was observed (p < 0.05) suggesting that the sperm population released from OECs in vitro presents potential fertilizing capacity. Improvements in handling and selection of cryopreserved sperm would improve efficiencies in ARTs allowing the use of a population of higher-quality sperm.

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

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

Sex Manipulation Technologies Progress in Livestock: A Review

Sex manipulation technologies allow predetermination of the sex of animal offspring by altering the normal reproductive process. In livestock production, the difference in type and gender can translate into significant economic benefits, including alleviation of severe food shortages. In livestock, however, the commercial application of sex manipulation technologies is currently available for cattle only. In this review, we described the brief history of sex manipulation, and the research progresses of common methods used in sex manipulation thus far. Information presented in this review can inform future studies on expanding the scope and use of sex manipulation technologies in livestock.

The Acrosomal Status of Density Purified Spermatozoa Differentiates Men from Couples in IVF and ICSI Treatment and Is Associated with Fecundity

The acrosome of the spermatozoa is required for fertilization and in the raw ejaculate the percentage of viable acrosome-intact spermatozoa, the acrosomal status, is higher among men with good semen quality. Here we investigated if the acrosomal status of the processed semen preparations used at a fertility clinic can also be informative and whether it is associated with fecundity. The acrosomal status was measured by image cytometry on purified semen samples from couples during in vitro fertilization (IVF) (n = 99) and intracytoplasmic sperm injection (ICSI) (n = 107) treatment. Purified frozen-thawed donor samples were also analyzed (n = 199). In purified semen preparations the acrosomal status was significantly higher among sperm donors (p = 5.3 × 10^-8) and men from IVF couples (p = 2.2 × 10^-5) when compared to men from ICSI couples. A significant difference was also found between female, male and mixed factor infertility (p = 0.003). No association with lifestyle factors was found. In frozen-thawed donor samples, a significant positive (r = 0.16, p = 0.025) association with the number of pregnancies per sold straw was observed together with an area under the curve of 75.3%, when comparing the top and bottom deciles. Our results indicate that the acrosomal status may be a valuable parameter for personalizing fertility treatments and might be a good predictor of pregnancy success among normozoospermic men.

Sperm velocity in a promiscuous bird across experimental media of different viscosities

In species with internal fertilization, the female genital tract appears challenging to sperm, possibly resulting from selection on for example ovarian fluid to control sperm behaviour and, ultimately, fertilization. Few studies, however, have examined the effects of swimming media viscosities on sperm performance. We quantified effects of media viscosities on sperm velocity in promiscuous willow warblers Phylloscopus trochilus. We used both a reaction norm and a character-state approach to model phenotypic plasticity of sperm behaviour across three experimental media of different viscosities. Compared with a standard medium (Dulbecco's Modified Eagle Medium, DMEM), media enriched with 1% or 2% w/v methyl cellulose decreased sperm velocity by up to about 50%. Spermatozoa from experimental ejaculates of different males responded similarly to different viscosities, and a lack of covariance between elevations and slopes of individual velocity-by-viscosity reaction norms indicated that spermatozoa from high- and low-velocity ejaculates were slowed down by a similar degree when confronted with high-viscosity environments. Positive cross-environment (1% versus 2% cellulose) covariances of sperm velocity under the character-state approach suggested that sperm performance represents a transitive trait, with rank order of individual ejaculates maintained when expressed against different environmental backgrounds. Importantly, however, a lack of significant covariances in sperm velocity involving a cellulose concentration of 0% indicated that pure DMEM represented a qualitatively different environment, questioning the validity of this widely used standard medium for assaying sperm performance. Enriching sperm environments along ecologically relevant gradients prior to assessing sperm performance will strengthen explanatory power of in vitro studies of sperm behaviour.

Methodological considerations for examining the relationship between sperm morphology and motility

Sperm cells of all taxa share a common goal to reach and fertilize an ovum, yet sperm are one of the most diverse cell types in nature. While the structural diversity of these cells is well recognized, the functional significance of variation in sperm design remains elusive. An important function of spermatozoa is a need to migrate toward the ova, often over long distances in a foreign environment, which may include a complex and hostile female reproductive tract. Several comparative and experimental studies have attempted to address the link between sperm morphology and motility, yet the conclusions drawn from these studies are often inconsistent, even within the same taxa. Much of what we know about the functional significance of sperm design in internally fertilizing species has been gleaned from in vitro studies, for which experimental parameters often vary among studies. We propose that discordant results from these studies are in part due to a lack of consistency of methods, conditions that do not replicate those of the female reproductive tract, and the overuse of simple linear measures of sperm shape. Within this review, we provide a toolkit for imaging, quantifying, and analyzing sperm morphology and movement patterns for in vitro studies and discuss emerging approaches. Results from studies linking morphology to motility enhance our understanding of the evolution of adaptive sperm traits and the mechanisms that regulate fertility, thus offering new insights into methods used in assisted reproductive technologies in animal science, conservation and public health.

Vitamin D Effects on the Immune System from Periconception through Pregnancy

Vitamin D is a well-known secosteroid and guardian of bone health and calcium homeostasis. Studies on its role in immunomodulatory functions have expanded its field in recent years. In addition to its impact on human physiology, vitamin D influences the differentiation and proliferation of immune system modulators, interleukin expression and antimicrobial responses. Furthermore, it has been shown that vitamin D is synthesized in female reproductive tissues and, by modulating the immune system, affects the periconception period and reproductive outcomes. B cells, T cells, macrophages and dendritic cells can all synthesize active vitamin D and are involved in processes which occur from fertilization, implantation and maintenance of pregnancy. Components of vitamin D synthesis are expressed in the ovary, decidua, endometrium and placenta. An inadequate vitamin D level has been associated with recurrent implantation failure and pregnancy loss and is associated with pregnancy-related disorders like preeclampsia. This paper reviews the most important data on immunomodulatory vitamin D effects in relation to the immune system from periconception to pregnancy and provides an insight into the possible consequences of vitamin D deficiency before and during pregnancy.

Motility Analysis of Trypanosomatids

Motility analysis of microswimmers has long been limited to a few model cell types and broadly restricted by technical challenges of high-resolution in vivo microscopy. Recently, interdisciplinary interest in detailed analysis of the motile behavior of various species has gained momentum. Here we describe a basic protocol for motility analysis of an important, highly diverse group of eukaryotic flagellate microswimmers, using high spatiotemporal resolution videomicroscopy. Further, we provide a special, time-dependent tomographic approach for the proof of rotational locomotion of periodically oscillating microswimmers, using the same data. Taken together, the methods describe part of an integrative approach to generate decisive information on three-dimensional in vivo motility from standard two-dimensional videomicroscopy data.

Marantodes pumilum (Blume) Kuntze (Kacip Fatimah) stimulates uterine contraction in rats in post-partum period

ETHNOPHARMACOLOGICAL RELEVANCE

Marantodes pumilum (Blume) Kuntze has traditionally been used to firm the uterus after delivery, however scientific evidences behind this claim is still lacking.

AIMS OF STUDY

To demonstrate Marantodes pumilum leaves aqueous extract (MPE) has an effect on uterine contraction after delivery and to elucidate the molecular mechanisms involved.

METHODS

Day-1 post-delivery female rats were given MPE (100, 250 and 500 mg/kg/day) orally for seven consecutive days. A day after the last treatment (day-8), rats were sacrificed and uteri were harvested and subjected for ex-vivo contraction study using organ bath followed by protein expression and distribution study by Western blotting and immunohistochemistry techniques, respectively. The proteins of interest include calmodulin-CaM, myosin light chain kinase-MLCK, sarcoplasmic reticulum Ca²⁺-ATPase (SERCA), G-protein α and β (Gα and Gβ), inositol-triphosphate 3-kinase (IP3K), oxytocin receptor-OTR, prostaglandin (PGF)2α receptor-PGFR, muscarinic receptor-MAChR and estrogen receptor (ER) isoforms α and β. Levels of estradiol and progesterone in serum were determined by enzyme-linked immunoassay (ELISA).

RESULTS

Ex-vivo contraction study revealed the force of uterine contraction increased with increasing doses of MPE. In addition, expression of CaM, MLCK, SERCA, Gα, Gβ, IP3K, OTR, PGF2α, MAChR, Erα and ERβ in the uterus increased with increasing doses of MPE. Serum analysis indicate that estradiol levels decreased while progesterone levels remained low at day-8 post-partum in rats receiving 250 and 500 mg/kg/day MPE.

CONCLUSIONS

These findings support the claims that MPE help to firm the uterus and pave the way for its use as a uterotonic agent after delivery.

One-Carbon Metabolism Regulates Embryonic Stem Cell Fate Through Epigenetic DNA and Histone Modifications: Implications for Transgenerational Metabolic Disorders in Adults

Human (h) and mouse (m) embryonic stem (ES) cells need specific amino acids to proliferate. mES cells require threonine (Thr) metabolism for epigenetic histone modifications. Thr is converted to glycine and acetyl CoA, and the glycine is metabolized specifically to regulate trimethylation of lysine (Lys) residue 4 in histone H3 (H3K4me3). DNA methylation and methylation of other H3 Lys residues remain unimpaired by Thr deprivation in mES cell culture medium. Similarly, hES cells require methionine (Met) to maintain the Met-SAM (S-adenosyl methionine) cycle of 1-carbon metabolism also for H3K4me3 formation. H3K4me3 is needed specifically to regulate and maintain both mES and hES cell proliferation and their pluripotent states. Better understanding of this regulation is essential since treatment of human diseases and disorders will increasingly involve hES cells. Furthermore, since ES cells are derived from their progenitor cells in preimplantation blastocysts, they serve as models of 1-carbon metabolism in these precursors of all mammalian tissues and organs. One-carbon metabolism challenges, such as a maternal low protein diet (LPD) during preimplantation blastocyst development, contribute to development of metabolic syndrome and related abnormalities in adults. These 1-carbon metabolism challenges result in altered epigenetic DNA and histone modifications in ES progenitor cells and the tissues and organs to which they develop. Moreover, the modified histones could have extracellular as well as intracellular effects, since histones are secreted in uterine fluid and influence early embryo development. Hence, the mechanisms and transgenerational implications of these altered epigenetic DNA and histone modifications warrant concerted further study.

Sialylated Cervical Mucins Inhibit the Activation of Neutrophils to Form Neutrophil Extracellular Traps in Bovine in vitro Model

In order to combat invading pathogens neutrophils can release neutrophil extracellular traps (NETs). However, since NETs can also damage endogenous cells, several control mechanisms for the formation of NETs must work effectively. For instance, neutrophil activation is silenced within blood circulation by the binding of sialylated glycoconjugates to sialic acid binding immunoglobulin-like lectins (Siglecs) on neutrophils. As neutrophils are recruited within the female reproductive tract, after mating, a comparable mechanism may also take place within the bovine cervix to prevent an exaggerated NET formation and thus, infertility. We examined, if the highly glycosylated mucins, which are the major functional fraction of biomolecules in mucus, represent a potential regulator of NET formation. The qPCR data revealed that in polymorphonuclear neutrophils (PMNs) inhibitory Siglecs are the most frequently expressed Siglecs and might be a potential target of sialylated glycans to modulate the activation of PMNs. Remarkably, the addition of bovine cervical mucins significantly inhibited the formation of NET, which had been induced in response to lipopolysaccharides (LPS) or a combination of phorbol myristate acetate (PMA) and ionomycin. The inhibitory effects were independent of the stage of estrous cycle (estrus, luteal, and follicular mucins). PMNs retained their segmented nuclei and membrane perforation was prevented. However, the inhibitory effects were diminished, when sialic acids were released under acidic conditions. Comparable results were achieved, when sialic acids were targeted by neuraminidase digestion, indicating a sialic acid dependent inhibition of NET release. Thus, bovine cervical mucins have an anti-inflammatory capability to modulate NET formation and might be further immunomodulatory biomolecules that support fertility.

Expression of Immune Regulatory Genes in the Porcine Internal Genital Tract Is Differentially Triggered by Spermatozoa and Seminal Plasma

Mating or cervical deposition of spermatozoa or seminal plasma (SP) modifies the expression of genes affecting local immune defense processes at the oviductal sperm reservoir in animals with internal fertilization, frequently by down-regulation. Such responses may occur alongside sperm transport to or even beyond the reservoir. Here, immune-related gene expression was explored with cDNA microarrays on porcine cervix-to-infundibulum tissues, pre-/peri-ovulation. Samples were collected 24 h post-mating or cervical deposition of sperm-peak spermatozoa or SP (from the sperm-peak fraction or the whole ejaculate). All treatments of this interventional study affected gene expression. The concerted action of spermatozoa and SP down-regulated chemokine and cytokine (P00031), interferon-gamma signaling (P00035), and JAK/STAT (P00038) pathways in segments up to the sperm reservoir (utero-tubal junction (UTJ)/isthmus). Spermatozoa in the vanguard sperm-peak fraction (P1-AI), uniquely displayed an up-regulatory effect on these pathways in the ampulla and infundibulum. Sperm-free SP, on the other hand, did not lead to major effects on gene expression, despite the clinical notion that SP mitigates reactivity by the female immune system after mating or artificial insemination.

Progesterone induces the release of bull spermatozoa from oviductal epithelial cells

The mechanism that causes the detachment of spermatozoa from the oviductal reservoir around the time of ovulation remains to be elucidated. Because the cumulus cells of the bovine oocyte are known to secrete progesterone (P4), and P4 has been shown to act upon cation channels of spermatozoa (CatSper) in human spermatozoa, it was hypothesised that P4 could induce hyperactivation due to an influx of extracellular calcium, and this would facilitate detachment of spermatozoa from oviductal epithelial cells. Therefore, this study aimed to investigate the role and mechanism of action of P4 in the release of spermatozoa from bovine oviduct epithelial cells (BOEC). Initial dose–response assessments on sperm hyperactivation determined the optimum concentration of P4 (10 nM), mibefradil (a non-specific Ca2+ channel antagonist; 5µM), NNC 55-0396 dihydrochloride (NNC; a CatSper antagonist; 2µM), mifepristone (a classical and membrane P4 receptor antagonist; 400nM) and AG205 (a membrane P4 receptor antagonist; 10μM). BOEC explants were incubated with frozen–thawed bovine spermatozoa for 30min, following which loosely bound spermatozoa were removed. Two experiments were completed. In Experiment 1, BOECs were treated for 30min with either no treatment, P4, NNC, mibefradil, P4+mibefradil, P4+NNC, P4+mibefradil+NNC or P4+EGTA. In Experiment 2, BOECs were treated for 30min with either no treatment, P4, mifepristone, AG205, mifepristone+AG205, P4+mifepristone, P4+AG205 or P4+mifepristone+AG205. The number of spermatozoa remaining bound per millimetre squared of BOEC explant was determined. Progesterone stimulated the release of bound spermatozoa from BOEC explants, whereas NNC, mibefradil and EGTA inhibited this release. The release of spermatozoa by P4 was inhibited in the presence of both mifepristone and AG205, whereas the combination of both had the greatest inhibitory action on P4 release of spermatozoa. These findings suggest the presence of a P4 membrane receptor on bovine spermatozoa and that P4-induced release of spermatozoa from BOECs is likely mediated by extracellular Ca2+.

Hyperactivated stallion spermatozoa fail to exhibit a rheotaxis-like behaviour, unlike other species

The journey of spermatozoa through the female genital tract is facilitated by rheotaxis, or the cell's preference to swim against a flow, as well as thigmotaxis, the wall tracking behaviour, which guides them to the site of fertilisation. The aim of this study was to characterise the rheotactic and thigmotactic response of stallion sperm within a microfluidic channel. Stallion sperm rheotaxis was assessed within the microfluidic channel with regard to: (i) A range of flow velocities, (ii) Varying media viscosity and (iii) Sperm hyperactivation. Sperm distribution across the microfluidic channel was also studied and compared to human and ram sperm. Stallion sperm progressed furthest at a velocity range of 10-30 µm/s, with an optimum velocity of 20 µm/s. A flow viscosity of 2.5cP or greater reduced sperm rheotaxis (P < 0.05). Stallion sperm that were hyperactivated were unable to exhibit rheotaxis within the microfluidic channel, whereas, both hyperactivated human and ram sperm did exhibit positive rheotaxis under the same conditions. The number of sperm swimming near the microfluidic channel walls was higher than in the microfluidic channel centre (P < 0.05). This is the first study to illustrate that stallion sperm are rheotactically responsive and increasing viscosity reduces this response. We also demonstrated that sperm are predominantly inclined to swim along a surface and uniquely, hyperactivated stallion sperm are non-progressive and do not exhibit a rheotactic response unlike other species.