After the discovery of hypoxia-inducible factor-1 (HIF1), the importance of low oxygen conditions (hypoxia) in physiological responses has become recognized. This review focuses on the roles of hypoxia in ovarian physiology, especially during luteal phase. Because the reports concerning the roles of hypoxia in ovarian function are increasing, the understanding of this area will help further understanding of ovarian function.

Successful implantation relies on the interaction between a competent embryo and a receptive endometrium. The aim of the present study was to investigate genes specifically expressed in early invasive embryonic tissue versus decidual tissue using microarray analysis. Genes differentially expressed in the maternal compartment included chemokines, lipoproteins, growth factors and transcription factors, whereas the embryonic invasive tissue expressed genes commonly observed in invasive tumour-like processes. The results provide information about genes involved in early embryonic invasion and the control exerted by the surrounding decidua.

β-defensins are small cationic proteins that have been shown to play a pivotal reproductive–immunobiological role across a range of species including mice, macaques and men. This study profiles a cluster of 13 novel β-defensin genes along Chromosome 22 of the Equus caballus genome and characterises their expression in the reproductive tract of the stallion and mare. β-defensin preferential regional expression in the caput epididymis in the stallion and the oviduct in the mare suggests a possible role in immunoprotection of the equine reproductive tract.

The present study was undertaken to investigate the association between the chemokine RANTES and epididymal spermatozoa. RANTES and its receptors were not in the same sperm location, suggesting that if RANTES binds to mouse epididymal spermatozoa, it would be independent of the receptors. Our study provides a new basis for further investigations of the association of RANTES with spermatozoa.

The levels of trace elements in spermatozoa and whole semen may significantly affect male fertility. The aim of this study was to analyse the levels of Na, Cu and Se in human semen and GPx activity in seminal plasma: Na, Cu, Se and GPx are related to sperm characteristics and male fertility and their survey could improve male infertility diagnosis.

Obtaining control of the koala reproductive cycle in order to manipulate the timing of oestrus is a fundamental component of artificial insemination in this species. Synthetic progesterone implants were used to temporarily suppress oestrous cycle activity in female koalas. Implant removal resulted in the synchronous return to oestrus in three of the four treated animals. These results provide hope for the effective use of a progesterone-based oestrus synchronisation tool in the koala.

Early embryo mortality hinders fertility in domestic species and humans, and is associated with poor maternal receptivity. Receptivity depends on sex-hormone priming of the maternal tissue to result in balanced secretions of nutrients and growth factors for the embryo. Here, we showed that abundance of molecules important for embryo receptivity differs according to the region of the reproductive tract. This provides the molecular basis for the characterisation of microenvironments within the reproductive tract that are associated with embryo receptivity and fertility.

The use of chilled semen has a special importance in canine breeding; however, the quality of chilled dog semen decreases during cold storage. This study compared the efficacy of simple sperm washing (SW), single-layer centrifugation (SLC) and modified swim-up (SU) techniques in the preparation of dog spermatozoa for cooling. It was concluded that SU through Androcoll-C can be integrated into canine semen preservation protocols.

C-Type natriuretic peptide (CNP) plays an essential role in maintaining meiotic arrest of mouse and porcine oocytes. Herein we studied the effect of CNP on spontaneous maturation of oocytes from the domestic cat and found that CNP is required to maintain oocyte meiotic arrest and prevent oocyte degeneration in this species. Therefore, CNP seems ubiquitously involved in the meiotic arrest of oocytes in mammals.

Bovine oocytes are particularly difficult to cryopreserve successfully. In the present study we examined whether exposure of in vitro-matured bovine oocytes to high concentrations of NaCl or sucrose before vitrification and warming would improve their cryotolerance. Pretreatment with 375 mOsmol NaCl or sucrose had no adverse effects on the spindle status of vitrified–warmed cow oocytes. However, sucrose pretreatment offered no benefits for embryo development.

There are many problems with trying to grow or culture follicles and eggs outside the human body for reproductive therapies. Even with current best practice, success rates of 10% or less are commonplace. We show that paying particular attention to the level of oxygen in the culture environment can greatly improve follicle growth.

Endometrial prostaglandins (PGs) are the most important modulators of the oestrous cycle and are regulated by ovarian hormones. This study aimed to clarify the regulatory mechanisms of progesterone on PG production. Our findings demonstrate that progesterone has at least two actuating pathways and precisely controls PG production by regulating enzymes of the arachidonate cascade via genomic pathways and by controlling signal transduction via non-genomic pathways.

This study explored the relationship between testis miRNAs and sperm DNA damage. We found that miR-424/322 was significantly downregulated in semen of patients with severe DNA damage and its downregulated expression in mouse testis increased sperm DNA damage. This is, therefore, a novel mechanism of sperm DNA damage and potential therapeutic target.

Mammalian epididymides secrete proteins into the lumen, which contribute to sperm maturation. The aim of the present study was to investigate the activity and distribution of lysosomal enzymes in bull epididymides at two different reproductive ages. It was found that enzyme activity and distribution vary during sexual maturity in bull epididymides and are regulated by mannose-6-phophate receptors. These findings could provide some molecular basis for male infertility.

Age at puberty is an important trait for reproductive performance of cattle, so the identification of genes regulating this character could assist in the selection for early pubertal animals. Through an association analysis in Angus bulls, two candidate genes for puberty were detected. These results could contribute to the understanding of puberty regulation and advanced research in the context of reproduction.

Assessment of semen quality is important to improve fertility in the buffalo. The aim of this study was to assess the seminal plasma protein profile in relation to semen function. We found that tuberoinfundibular peptide of 39 residues (TIP39) protein in seminal plasma was important for maintaining sperm function and fertilising ability. TIP39 could be a potential molecule to assess semen quality in buffalo bulls.

How pathogens lead to pregnancy failure remains unclear. To explore signal transduction in the effects of pathogens, a mouse model of pathogen-induced embryo loss was established. Pathogen-produced double-stranded RNA may activate an immune response via interferon regulatory factor 4, subsequently leading to embryo loss. The findings of the present study may be useful in preventing or treating infection-related pregnancy failure.

Leukaemia inhibitory factor (LIF) is essential for murine blastocyst survival and implantation. We demonstrate that LIF expression increases at the conceptus–maternal interface in the mare when the trophectoderm and endometrium first come into direct contact, i.e. as the intervening blastocyst capsule disintegrates. Since LIF receptor expression in the trophoblast increases simultaneously, we propose that LIF contributes to trophoblast development and non-invasive implantation in horses.