Male Reproductive Biology

Male Reproductive Biology

Male reproductive biology is one of the core areas in reproductive sciences. From conception, our biological sex is determined by our sex chromosomes. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). However, certain genetic anomalies or variations in sexual development can disrupt this process. Cases of sex reversal, where an XX individual develops male characteristics or, conversely, an XY individual develops female characteristics, are of particular interest to the teams of Nicolas Pilon and Robert S. Viger. More specifically, Nicolas Pilon studies sex-related conditions such as Hirschsprung's disease, which is four times more common in boys than in girls, and CHARGE syndrome (subfertility and male-to-female sex reversal).

Testis

The testis is the central organ of the male reproductive system. It has two main roles: producing sperm and synthesizing sex hormones such as testosterone.

Sperm production relies on the activity of spermatogonial stem cells (SSCs), which are present from birth and capable of both self-renewal and differentiation throughout life. Makoto Nagano's team explores strategies to preserve this capacity, with the goal of developing fertility preservation approaches.

Inside the testis, Sertoli cells nourish and support the cells that will become sperm, while Leydig cells produce testosterone, a hormone essential for the proper functioning of this entire process. Within the RQR, several research teams are studying testicular function. Alexandre Boyer’s team focuses on the development and proper function of the testes, particularly how mature Sertoli cells support germ cells by providing a stable, nourishing, and protective environment. Robert S. Viger investigates how certain genes are activated or deactivated in the testicular cells that support sperm production, such as Sertoli and Leydig cells. Jacques J. Tremblay’s research group is also interested in the development and function of Leydig cells.

Vas efferens and Epididymis

Once produced, immature sperm are transported from the testis to the epididymis via the vas efferens. It is during their transit through the epididymis that sperm maturation occurs—a crucial process that enables them to acquire motility and the ability to fertilize an egg. The epididymal environment, rich in proteins, lipids, and enzymes, plays a key role in the acquisition of these functional properties. The teams of Daniel Cyr, Sylvie Breton, and Clémence Belleannée study the physiology of the vas efferens and epididymis. Their research opens new avenues for developing treatments for male infertility and for creating male contraceptives.

Prostate

The prostate is a gland of the male reproductive system located beneath the bladder. It produces part of the seminal fluid, which is essential for sperm survival and motility. With age, the prostate can be affected by conditions such as benign prostatic hyperplasia or prostate cancer. The teams of Clémence Belleannée and Étienne Audet-Walsh study the function of this gland and aim to develop new approaches for treating prostate cancer.

Reproductive Function

A sperm cell's ability to fertilize an egg depends on specific transformations that occur after ejaculation. Pierre Leclerc’s team studies capacitation, a process that enables the sperm to fertilize by modifying its membrane and enzymatic activity. Cristian O’Flaherty and his team investigate how sperm acquire their fertilizing capacity and the role of reactive oxygen species (ROS) in this process. Although these molecules can damage sperm at high concentrations, they are beneficial in low amounts. The team also explores the influence of the gut microbiome on male fertility.

The quality of sperm and their fertilizing potential depend on the environment and the proper functioning of the organs in the male reproductive system. Exposure to toxic substances in the environment or resulting from lifestyle habits can impair the function of these organs and affect male fertility. The teams of Géraldine Delbès, Sarah Kimmins, and Bernard Robaire study the effects of such factors on male reproductive health and on the health of their offspring.