Male Reproductive System

The male reproductive system consists of a pair of testes, epididymis, vas deferens, prostate, seminal vesicle and the urethra. Each feature plays an important role in the production and maturation of spermatozoa.

Here we will start looking about the testis. Within the testis, from birth, there is a process of mitosis occurring. This allows the production of new, identical germ line cells to be formed. At puberty, in a male, a hormone called testosterone is produced and released into the blood stream and this causes some of the germ line cells to undergo the first meiotic division, Meiosis I. Meiosis I forms haploid cells which contain half of the amount of genetic material, chromosomes (There are 46 chromosomes within a human and these get halved to 23 individual chromosomes). After meiosis I has finished, Meiosis II occurs, where crossing over of bivalent chromatids at the chiasmata to produce four spermatids, each of a random assortment of the parent cells genetic information. No spermatids are equal to each other. In other words, each spermatid has different genetic material due to crossing over at the chiasmata during the second meiotic division. The spermatids are then protected and nourished by a cell called the Sertoli Cell. This cell has the ability to protect the spermatid from the immune system of the male. The spermatids take up to a month to be produced and pass into the epididymis.

The Epididymis is a sac like structure, attached to each testis, which acts like a bag to hold the spermatids until they develop into spermatozoa. After maturation, the sperm are then transported into the seminal vesicle by movements of peristalsis by the vas deferens.

At the seminal vesicle, the spermatozoa is mixed with seminal fluid, which makes up a percentage average around sixty percent of the ejaculate produced. The spermatozoa remain at this point until the male becomes sexual stimulated. Once sexually stimulated, the spermatozoa pass into the urethra to exit the penis as ejaculate. Some of the sperm is propelled strong enough through the thick muscular cervix. This is where the sperm enter the female reproductive track and make their way up to the ovum at ovulation in a woman.

Biology


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