The reproductive tract of live-bearing mammals undergoes vast remodelling to accommodate the developing embryo. The aim of this study was to determine the effect of the reproductive hormones progesterone and 17β-oestradiol on the reproductive tract of the marsupial Sminthopsis crassicaudata. We concluded that the remodelling of the uterine epithelium is regulated by the same hormonal mechanisms among mammalian species.

In all, 3163 microRNAs (miRNAs) were expressed and detected in mouse blastocysts and outgrowth embryos. Of these, the expression of10 miRNA candidates (let-7b, miR-23a, miR-27a, miR-92a, miR-183, miR-200c, miR-291a, miR-425, miR-429 and miR-652) was identified as significantly different in outgrowth embryos. These differentially expressed miRNAs could be involved in embryo attachment and the implantation process between the embryo proper and the maternal endometrium.

Platelet-activating factor (PAF) is a well-known growth factor, modulating various physiological processes, including reproduction. For many years, PAF was believed to reside solely at the plasma membrane. Here, we describe for the first time its nuclear origin in oocytes and embryos of cattle, mice and humans. This distinct location hints towards unique subcellular functions, left to be characterised.

Approximately 45% of azoospermia patients are able to father their own offspring via microsurgery, but there is no reliable test to predict testicular spermatozoa existence before the surgery. We detected and compared specific molecules called microRNAs in the testis from patients whom spermatozoa were successfully versus unsuccessfully extracted, and found that there were significant differences between the two groups. The findings suggest the possibility of using differentially expressed microRNAs in the testis of the patients as a non-invasive technique for preoperative diagnoses.

The testes of most mammals need to be cooler than body temperature; increased temperatures cause formation of abnormal spermatozoa and poor fertility. When ram testes were warmed, there was increased blood flow and adequate oxygen. These results challenge a long-standing belief that testicular warming causes inadequate oxygen and may enable novel treatments to protect spermatozoa from the negative effects of increased testicular temperature.

Exposure to high levels of oestradiol that produces local accumulation of active oestrogen metabolites can affect normal implantation. Herein the role of 2-methoxyoestradiol on the anti-implantation effect of oestradiol in the mouse was investigated. We found that oestradiol impairs embryo implantation through its conversion to 2-methoxyoestradiol and subsequent increase of F-spondin in the mouse uterus. These findings highlight the role of 2-methoxyoestradiol in embryo implantation failures under hyperoestrogenic conditions.

Transcription factors are essential mediators of ovulation and luteinisation. The present study demonstrates that there are significantly increase in levels of the transcription factor high mobility group AT-hook 1 (HMGA1) after administration of human chorionic gonadotropin to rats. Induction of Hmga1 mRNA is mediated through both the protein kinase (PK) A and PKC signalling pathways by activation of the epidermal growth factor receptor and requires the synthesis of a new protein(s). Temporal stimulation of HMGA1 may be important for theca and granulosa cell differentiation into luteal cells.

This study investigates the interspecific diversity in relative testes mass (RTM) and sperm morphology across the Philippine chrotomyine rodents. Major interspecific differences were found with coevolution being evident between RTM, sperm head shape and sperm tail length. The findings suggest differences in intensity of intermale sperm competition and hence breeding system across the species.

Sperm macrocephaly syndrome (SMS), characterised by spermatozoa with enlarged heads and multiple tails, has not been described in birds. In the ostrich, affected spermatozoa are diploid, swim slower but straighter and the multiple tails are collectively bound within the cell membrane. SMS can occur in birds and may adversely affect breeding programs, particularly for endangered species.

Haemoglobin is an important protein commonly found in red blood cells. In addition to carrying oxygen around the body, haemoglobin has the capacity to act as an antioxidant. We discovered surprisingly high amounts of haemoglobin in embryos grown in mice compared with those grown in the laboratory, which had much lower haemoglobin concentrations. Haemoglobin may play an important role in regulating oxygen during early embryo development and the absence of this protein may affect the health of embryos grown in the laboratory.

Seasonal breeders have distinct reproductive strategies, which include synchronised cycles of active and inactive epididymal function between the breeding and non-breeding seasons. The expression of pituitary-derived hormone receptors was positively correlated with morphological and histological changes in the epididymis of the wild ground squirrel. Pituitary-derived hormones may regulate the epididymal functional changes required to adapt to seasonal environmental changes.

In sheep, the association between temperament associated with two single nucleotide polymorphism (SNP) genotypes and sheep reproduction has not yet been studied. This study investigated the association between steroid 17-alpha-hydroxylase/17,20 lyase (CYP17) SNP628 and dopamine receptor D2 (DRD2) SNP939 genotypes and concluded that sheep with the DRD2 SNP939 T/T genotype combined with the CYP17 SNP628 G/G genotype had better reproductive performance and maternal behaviour. The findings may be beneficial for sheep genetics and breeding.

Optimum luteal function is essential for sound reproductive health in animals. In the present study, regulation of luteal function by thrombospondins and insulin was demonstrated in water buffalo and it was observed that thrombospondins impaired progesterone production by decreasing the viability of luteal cells, whereas insulin reversed the findings. This observation will help in controlling the life span of the corpus luteum and its function.

We report two novel and unique phenotypes of MRL/MpJ mice in the female reproductive function. Superovulation treatment resulted in the production of significantly more oocytes with lower quality, and the faster luteinisation of ovulated follicles in MRL/MpJ than C57BL/6 mice. Our results provide novel insights into the effects of artificial ovulation on oocytes and ovaries in mice.

Epididymal spermatozoa of the Chinese soft-shelled turtle possess usually large cytoplasmic droplets with several lipid droplets (LDs), which serve as an important energy source. During long-term sperm storage in the epididymis, LDs were degraded by lipophagy to sustain sperm longevity. Understanding the mechanism underlying sperm storage would provide insights into the reproductive strategy of the Chinese soft-shelled turtle and contribute to further studies on sperm conservation in vitro.

In addition to diabetes, the clinical use of metformin in different pathologies is growing, and late-phase clinical trials of metformin in cancer therapy are underway. This study investigates the effects of metformin on human spermatozoa, and demonstrates undesirable effects, namely inhibition of sperm motility and essential sperm signalling pathways. This study is relevant to human reproduction, particularly for the fertility of patients who may be treated with metformin in the future.

Although hibernation is an integral part of the life history of species living in seasonal environments, little is known about how hibernation affects reproductive success in amphibians. Our study shows that sperm output (quality and quantity) was not affected by hibernation lengths in the endangered Wyoming toad. These unexpected findings illustrate the potential of temperate amphibians to adapt to varying environmental conditions during winter months.

Not surprisingly, the number of oocytes is correlated with litter size, but the effects of mitochondrial (mt) DNA polymorphisms on porcine oocyte numbers remain unclear. In this study, mtDNA polymorphic sites, haplotypes and haplogroups were significantly associated with the number of porcine oocytes. Particular mtDNA haplotypes in pigs can be used as potential molecular markers for selection based on oocyte quantity and litter size.

Ovaries secrete anti-Müllerian hormone (AMH), which stimulates gonadotrophin secretion from gonadotrophs in bovines. This study revealed that gonadotrophs themselves express AMH. The AMH expression levels in anterior pituitaries (APs) were not affected by oestrous phase. The APs of old Holsteins exhibited lower AMH mRNA levels but higher AMH protein levels than those in young Japanese Black APs.

Accurate dissection of blastocysts into inner cell mass and trophectoderm is critical for numerous experiments in embryology and developmental biology. We show that serum from α-1,3-galactosyltransferase deficient pigs can be used as an antibody source for embryo immunosurgery in several species, which allows standardised experimental approaches and facilitates comparative developmental studies, e.g. in lineage-specific transcriptome profiling and chimeric aggregation studies.