Physiology of sperm cells

It originally needed that extra speed to break the egg barrier. Later on, evolution enabled sperm to use its souped-up swimming to navigate tricky reproductive pathways even before reaching the egg. That is the finding of a new study led by Jean-Ju Chung , an assistant professor of cellular and molecular physiology at the Yale School of Medicine. The study appears in the journal Cells. In her previous work, Chung has looked at the molecular structures and mobility of sperm in placental mammals such as mice and humans. Placental mammals are distinguished by the presence of a placenta that sustains the fetus during development.

The testes are where sperm are produced. The testes are linked to the rest of the male reproductive organs by the vas deferens, which extends over the base of the pelvic bone or ilium, and wraps around to the ampulla, seminal vesicle, and prostate. The urethra then runs from the bladder through the penis. Along the top of each testicle is the epididymis. This is a cordlike structure where the sperm mature and are stored.

Compared to other species, human males have relatively poor sperm producing capacity and human testicular function is very sensitive to a wide variety of environmental insults. This may be related to the human upright posture and hydrostatic pressure on venous testicular outflow, or other unknown factors, but it is necessary for clinicians to be aware of the high incidence of subfertility in men. Perhaps it is a reflection of the incredible ability of humans to adapt the environment to promote their own survival or the expectation that fertility should be nearly spontaneous, but many human couples seek evaluation for infertility. The human male reproductive system includes the hypothalamic-pituitary-testis axis as well as the epididymis, vas deferens, seminal vesicles, prostate and urethra. Production of spermatozoa requires approximately 3 months from the initial mitotic divisions through the myriad changes readying sperm for ejaculation and fertilization.

Semen , also known as seminal fluid , is an organic bodily fluid created to contain spermatozoa. It is secreted by the gonads sexual glands and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. Semen is produced and originates from the seminal vesicle , which is located in the pelvis. The process that results in the discharge of semen from the urethral orifice is called ejaculation. In humans, seminal fluid contains several components besides spermatozoa: proteolytic and other enzymes as well as fructose are elements of seminal fluid which promote the survival of spermatozoa, and provide a medium through which they can move or "swim".