Human Reproductive System 1 Netter’s, et al, Images used under Fair Use Copyright Practice for Educational Purposes. DISCLAIMER! • This lecture is a clinically and scientifically frank ADULT discussion about the human reproductive system with ADULT students who are studying to go into fields of health care and need a fundamental knowledge of: – The anatomy and physiology of the human reproductive system, – Elementary concepts of anatomy, physiology and biochemistry of sexual intercourse, and – Embryogenesis, fetal development, gestation and delivery of the human fetus. • If you feel uncomfortable with and/or about this[these] topic[s], it is quite likely that you’re probably not going into an appropriate field of study for your future and may wish to reconsider your career path. You’ve been forewarned. 2 Perineal Musculature – Compare and Contrast – Male and Female 3 Male Reproductive System • The penis is the organ of copulation and is an accessory organ. • The reproductive organs in the male are the testes. • The dartos is involuntary muscle that puts the wrinkles in the scrotum; remember the cremaster is the muscle that lifts the testes towards the body or lowers them from the body. • The epididymis is 4-6 meters in length and is where spermiogenesis (sperm maturation) occurs. • It takes sperm about 12 days to traverse the epididymis. • Spermatogenesis (production of sperm) takes place, specifically, in the seminiferous tubules. • The testes produce the sperm and secrete testosterone. 4 5 Male Reproductive System • The seminal vesical secretes fructose, vitamin C, prostaglandins, amino acids and the bulk of the semen. • It also contains clotting precursors (fibrinogen) and is a yellowish, alkaline fluid. • The prostate gland is about the size of a chestnut, contains two lobes and is a firm organ. • It secretes "plasmin". • The fluid released from the prostate is thin, milky, alkaline and makes up about a third of the semen. • Cowper's glands are utilized to flush the urethra of residual urine or other substances that will damage the sperm when they are ejaculated through the urethra. • These secretions are alkaline and mucous-like; they provide only about 2-3 drops of lubricant, so these glands aren't of great significance in terms of lubrication for intercourse. • In general, the volume of semen runs around 3-6 mL and contains in the neighborhood of 300 to 400 million sperm. • Succeeding ejaculates in a short period of time contain a smaller volume of semen. 6 • Spongy urethra, Prostatic urethra, Membranous urethra . • The spongy urethra is approximately 15 cm in length. 7 Male Reproductive System • This graphic simply reinforces that which you learned in the chapter on muscles and illustrates some orientation of organs with vessels and other anatomical landmarks. • Note that the spermatic cord contains blood vessels and nerves to provide a source of nourishment, sensation and waste removal for the testes. 8 • At 7 months of gestation, the testes Testis descend towards the inguinal canal from the abdominal cavity. • By 8 months, they are generally through the inguinal canal. • The outer coating of the testis (the tunica albuginea) is eventually surrounded by the tunica vaginalis (this if from "vaginal“ growth during embryological differentiation). • At 7 months, the tunica vaginalis "drops" into the scrotum; at 8 months, it is in the scrotum anterior to the testis. • By one month of post-natal age, it is called the tunica vaginalis. • The tunica albuginea give rise to the septa in the testes, which separate the tissue into lobules. • The lobules consist of the seminiferous tubules (where the sperm are synthesized). • ALL seminiferous tubules converge on the rete testis and the epididymis. 9 What Can Go • Cryptorchidism occurs when testes Wrong do not descend into the scrotum. • The left graphic illustrates various sites where these testes may be found. "A" is the site of greatest frequency and "D" is the site of least frequency. • Note that "A" is the site between the inguinal canals (deep ring and shallow ring). • Ectopic testes occur when the testes descend through the two inguinal canals, but get "side- tracked". • Note the different sites of ectopism illustrated with the oval shapes. • Approximately 5% of undescended testes are ectopic. 10