Male Reproductive System

Reproductive system is designed and crafted by nature over time to help sperm travels from its home, the testes, to its partners, the oocyte. Sperm starts from the testes, matures and is stored in the epididymis, passes through seminal vesicle and the prostate gland and is released through the vas deferens, ejaculatory duct and urethra. Testes produce sperm and testosterone. Therefore if they are damaged this can affect semen quality. Damage can occur through infection, injury or surgery. Vas deferens is a smooth muscle duct which transports sperm from the epididymis into the ejaculatory duct. (6)

Spermatogenesis happens in testes. Spermatogenesis is the process of producing motile sperm cells also known as spermatozoa from primordial germ cells in males. The process begins with spermatogonia, which are undifferentiated germ cells found in the seminiferous tubules in the testis. Spermatogonia (2n) divide by mitosis to produce 2 daughter cells. One of which is a spermatogonium (2n) and the other a primary spermatocyte (2n). The primary spermatocyte divides by meiosis to produce secondary spermatocytes (n). Secondary spermatocytes divide again producing spermatids (n). Spermatids, contain the correct number of genes to act as gametes. In order to obtain their physical characteristics spermatids differentiate into sperm cells.  (9)

Sperm need specialized structures to increase speed and efficiency. Each sperm consists of a head ,middle piece and tail covered by a single plasma membrane. The haploid nucleus is located in the head of the sperm cell. The acrosomal vesicle located in the head of the sperm secretes hydrolytic enzymes that help the sperm penetrate the outer membrane of the egg and bind it tightly. Highly specialized mitochondria at the midpiece generate ATP that is hydrolysed to provide energy for flagellar movement of the sperm tail.  (4) 

Luteinizing hormone (LH) and follicle stimulating hormone (FSH) play an important role in the production of sperm. LH and FSH are released in the blood stream from anterior pituitary gland and act on the testis. FSH acts on the Sertoli cells in testis to stimulate the production of sperm. LH acts on the Leydig cells to trigger the production of testosterone, an essential steroid hormone that aids sperm production. (4)

Semen is the fluid produced by males for sexual reproduction and is ejaculated out of the body during sexual intercourse. In healthy adult males, semen contains above 15 million sperm cells per millilitre. The seminal vesicle secretions comprise 60% and the prostate gland fluids contribute to 30% of semen.The function of semen is to ensure sperm self-motility. Potassium and magnesium, the presence of adequate amounts of oxygen in the plasma, proper temperature, and a slightly alkaline pH help the sperm move freely within the vagina after intercourse and to neutralize the acidic environment.  (5)

Penis deliver semen to the vagina during ejaculation. Nitric oxide is the neurotransmitter responsible for blood flow into the penis, causing it to be erect and turgid. Penis muscle contract and projects seminal fluid out. However, problem can occur during ejaculation  thus preventing the sperm to meets the egg,example premature ejaculation where ejaculation happens too fast so not enough semen may be deposited in the vagina.

A low sperm count (oligospermia) is fewer than 15 million sperm per milliliter of semen or fewer than 39 million per ejaculate. There are two possible causes of low sperm count which is obstructive  such as trauma, and non- obstructive like medicine. The abnormal shape and size of sperm may affect the possibility to fertilize an egg. The classification of sperm motility is described into 4 parts, straight and zig-zag moving, vibrating and also non-motile. The problem is the slow movement of sperm to reach the egg in female reproductive tract. Sperm movement is activated by changes in intracellular ion concentration, also pH.