Assisted reproductive technologies like artificial insemination help address equine infertility, but selecting high-quality sperm beforehand can further boost fertility rates. Traditional methods like centrifugation may damage sperm DNA, whereas newer techniques – microfluidics (using tiny fluid channels to filter healthy sperm) and electrophoresis (sorting sperm by electric charge) – offer gentler alternatives. Innovations like VetMotl™ and Felix™ enhance sperm selection, improving pregnancy outcomes. While cost of these devices remains a challenge, ongoing research could make these advancements more accessible for equine breeding. Illustration by Ashlee Medica.

This article belongs to the collection: Frontiers in Reproduction Science – Rising Stars at the Society for Reproductive Biology 2024.

Wallabies require rapid embryonic development as they give birth after a short pregnancy, immediately followed by ovulation. We analyzed and quantified differences between the gravid and the non-gravid uterus, which included a greater blood vessel area and increased surface area in the gravid endometrium and investigated the features ensuring the most efficient embryo-maternal exchange, such as polyploidy of trophoblast cells. However, these adaptations seem to be self-limiting making birth at the designated time inevitable. Image by Marie Muenzenberger.

A very small proportion of eggs in the ovaries are ever ovulated but it is not known how the ovary chooses which eggs ovulate. We discuss the evidence that high-quality eggs produce signals that increase their rate of maturation allowing them to win the race to ovulate. If the ovary can detect which eggs are good quality, then it might be possible to adapt this to improve treatment in fertility clinics. Image by Michael Pankhurst.

This article belongs to the collection: The biology of the ovary – Honouring the contributions of Ken P McNatty and Rex J Scaramuzzi.

Regulated growth and development of ovarian follicles are important for fertility, and locally produced factors are key regulators of these processes. We investigated whether locally produced platelet derived growth factors (PDGF) play an important role in the growth and function of ovine follicles. Multiple PDGF ligands, as well as their receptors, were expressed in developing follicles, and PDGFBB altered key follicular functions, indicating these growth factors are important for the regulation of growth and development of ovarian follicles in sheep. Image by Jennifer Juengel.

This article belongs to the collection: The biology of the ovary – Honouring the contributions of Ken P McNatty and Rex J Scaramuzzi.

A temporal decline in human sperm counts and dog sperm motility has been linked with environmental factors. This viewpoint article explores the basis of this contention and its implications for male fertility. Image by Richard G. Lea using Biorender.

We give a brief overview of sperm–egg interactions at the time of fertilisation in an Australian hydromyine rodent, the Plains Mouse Pseudomys australis emphasising the unique features of its spermatozoon: the presence of two ventral processes. These may be the most morphologically complex sperm to have evolved in eutherian mammals, and may have evolved in an early common ancestor of the hydromyine rodents several million years ago. These ventral processes may facilitate the binding of the spermatozoon to the zona pellucida of the ovulated egg to maximise the chances of fertilisation. Photographs by William Breed.

Textbooks, websites and YouTube videos present misinformation about the ovary with statements and illustrations that are patently inaccurate or incorrect. Even multiple edition textbooks still have major misleading inaccuracies occurring in text and illustrations. Amongst other inaccuracies many report that the prepubertal human ovary is dormant and that a human primordial follicle grows into preovulatory follicles during the course of the follicular phase of 14 days. How did we get here and more importantly how can it be rectified? Diagram byProfessor Jeffrey B. Kerr.

This article belongs to the collection: The biology of the ovary – Honouring the contributions of Ken P McNatty and Rex J Scaramuzzi.

Establishing uterine receptivity to embryo implantation remains a major bottleneck in reproductive success – hence there is a need to better understand the underpinning biological mechanisms. This review summarises and integrates insights gained from gene expression studies that collectively demonstrate seminal fluid drives uterine immune and vascular changes accompanying acquisition of uterine receptivity. Defining the impact of seminal fluid on implantation biology will help us to better understand the determinants of healthy fertility, and develop novel interventions for managing reproduction in humans and animals. Illustration by Hon Y. Chan and Sarah A. Robertson using BioRender.

This article belongs to the collection: Frontiers in Reproduction Science – Rising Stars at the Society for Reproductive Biology 2023.

More couples are delaying childbearing, which unfortunately can negatively influence the health of their child. Using reproductively old mice at 12 months old, we examined the characteristics of the offspring of older mothers at birth, and then followed them to adulthood and measured markers of adult health, namely growth, glucose tolerance, immune function and behaviour. This study provides insights into how maternal age influences the health and development of their offspring. Image by Macarena B. Gonzalez.

This article belongs to the collection: Frontiers in Reproduction Science – Rising Stars at the Society for Reproductive Biology 2023.

The optimization of sperm freezing and storage program has an important impact on reducing breeding costs, improving reproductive efficiency, overcoming reproductive diseases, and protecting germplasm resources. In this paper, we have included two potential additives, sodium alginate (SA) and bovine serum albumin (BSA), which can effectively improve sperm motility after cryopreservation. This is of great significance for improving the quality of pig semen, improving reproductive ability and the development of modern pig breeding industry. Image by Jing Wang using Figdraw.

In the past decade, flow cytometry has emerged as a crucial tool for assessing cellular viability in non-domestic animals, including non-human primates, marine life, and birds. Its application in sperm-quality assessments could revolutionize how we evaluate sperm concentration and viability, enhancing efficiency and reliability. This study validated the effectiveness of flow cytometry in assessing amphibian sperm, demonstrating its viability when compared with traditional, time-consuming methods. Such advancements highlight the potential of flow cytometry to significantly streamline conservation efforts for amphibians. Photograph by Ingrid Niesman, SDSU EM Facility.