Reproductive System - Male

" And God created a Woman from ... "

LH - Luteinizing hormone - LH causes testosterone to be produced and released.

          Testosterone - Causes the formation of the primary sex characteristics at week 10 (growth of penis and reproductive organs), and at puberty the secondary sex characteristics (deep voice, large muscle mass, body hair growth).

FSH - Follicle stimulating hormone - Initiates sperm formation (spermatogenesis).

Scrotum - Is a bag that is external to the body and controls the temperature of the testes.

          Testes - Are where sperm are made, they must be kept at 95 degrees for normal sperm development.

                    Seminiferous tubules - Are coiled tubes inside the testis where sperm are produced continuously after puberty.

                    Interstitial cells - Cells outside and between the seminiferous tubules which make testosterone which is necessary for continued sperm production.

Sperm - Male gamete. Men make 200 million sperm / day (about 2,000/second).

          Head - Contains the nucleus which contains the 23 chromosomes.

                    Acrosome - A cap-like structure on the head of the sperm, contains enzymes used to penetrate the egg

          Body - Has mitochondria which make ATP

          Tail - Used for swimming.

Epididymis - leave the seminiferous tubules and complete maturity here (last about a month). From mother sperm cell till maturity = 75 days.

Vas deferens - Male has 1 from each testes that go from the scrotum into the body cavity.

Ejaculatory duct - Conveys the seminal fluid and sperm to the urethra.

Urethra - This tube carries either urine or sperm out through the tip of the penis.

Glans penis - The tip of the penis.

Baculum - Penis bone. Found in all primates except man. Baculum not in humans, marsupials, horses, rabbits, whales and dolphins.

Semen - Made of sperm (10%) and the fluid (90%) they are in. About 2 - 5 ml (1/2 a teaspoon) of semen are ejaculated during orgasm. There should be 50 - 150 million sperm/ ml.

          Sterile / Impotent - If he has less than 20 million sperm / ml.

Seminal vesicles - They add most (about 60%) of the fluid to sperm. They release a sugar which provides an energy source for the sperm. It also releases prostaglandins.

          Prostaglandins - Cause the female's uterus to contract.

Prostate gland - Its fluid (about 30 %) has a basic quality which neutralizes acids in the vagina.

Bulbourethral gland - Add a tiny amount of fluid which prepares and lubricates the urethra before ejaculation.

The Pathway of Gametes


Seminiferous Tubules --> Epididymis --> Vas Deferens --> Ejaculatory Duct --> Urethra

Return to Greg Sievert's GB 100 Syllabus
Last updated on 4 January 2018