Male Reproductive System Nestor T. Hilvano, M.D., M.P.H.

Learning Objectives Describe the components of the male reproductive system and state their functions. Describe the anatomy of the testes, scrotum, and penis. Explain the roles played by the male reproductive tract and accessory glands in maturation, nourishment, storage and transport of spermatozoa. Outline the process of spermatogenesis and describe the role of sertoli cells. Describe a sperm cell and trace the pathway taken by a sperm cell from its formation to its ejaculation. State the normal composition of semen. Discuss the hormonal control that regulate male reproductive functions. Discuss BPH and prostatic cancer.

Components and Functions of Male Reproductive System _______ – produce gametes and hormones - testes _______ - receive and transmit gametes - epididymis, ejaculatory duct, urethra _______ - secrete fluids - seminal vesicles, prostate gland, bulbo-urehtral glands _______ - perineal structures - scrotum, penis a. genital ducts b. accessory glands c. gonads d. external genitalia

Testes Male gonads, found in pouch called the scrotal sac. Descent of testes (2 to 7 months) - Gubernaculum testis (C.T.) shortens - Essential for ________ What is cryptorchidism?

Spermatic Cord Extend bet. Abdominopelvic cavity and testes Consist of layers of fascia and muscle What structures are contained in spermatic cord? Pass through inguinal canal, descend into scrotum _______ - protrusion of visceral tissues into inguinal canal a. femoral hernia b. hiatal hernia c. inguinale hernia d. all

Testes Tunica vaginalis Tunica albuginea Septa divide testes into compartments containing seminiferous tubules Sperm cells Sustentacular (nurse/sertoli) cells Interstitial (Leydig) cells produce _____. Estrogen b. Testosterone c. FSH d. LH

Spermatogenesis Spermatogenesis- differentiation from spermatogonium to spermatozoas (sperm cells) Stages of spermatogenesis: Mitosis = Spermatogonia - type A produce more daughter cells (type A); some forms type B Growth = type B differentiate into primary spermatocytes Meiosis - MI  primary spermatocytes to secondary spermatocytes - MII  secondary spermatocytes to spermatids 4. Spermiogenesis= transformation of spermatids to spermatozoas (sperm cells)

Spermatic Ducts Efferent ductules Epididymis (head, body and tail) collecting sperm from semineferous tubules Epididymis (head, body and tail) coiled duct adhering to posterior of testis Function _____________ Ductus deferens muscular tube 45 cm long Ejaculatory duct formed from union of _____________ and duct of _____________.

Male Urethra ___Prostatic ___Membranous ___Penile Middle and shortest segment Traverses the corpus spongiosum; longest segment First segment

Accessory Glands Seminal vesicles posterior to bladder Secretion ___________ Prostate gland below bladder, surrounds urethra and ejaculatory duct Bulbourethral glands near bulb of penis; lubricating fluid Mucus and alkaline b. acid phosphatase c. Fructose d. lactose

Penis Root, shaft, and glans skin over shaft loosely attached prepuce (foreskin) 3 cylindrical bodies of erectile tissue corpus spongiosum encloses ____________ corpora cavernosa

Hormonal Control Hypothalamus produces GnRH Stimulates anterior pituitary to secrete LH stimulates interstitial cells to produce testosterone FSH stimulates sustentacular cells to secrete androgen-binding protein that interacts with testosterone to stimulate spermatogenesis

Effects of Testosterone Enlargement of secondary sexual organs During adulthood, testosterone sustains libido, spermatogenesis and reproductive tract

Semen or Seminal Fluid 2-5 mL of fluid Other components of semen 60% seminal vesicle fluid, 30% prostatic normal sperm count 20-100 million/mL Other components of semen fructose - energy for sperm motility fibrinolysin liquefies semen within 30 minutes prostaglandins stimulate female peristaltic contractions spermine is a base stabilizing sperm pH at 7.2 to 7.6

Excitement and Ejaculation Erection of penis - parasympathetic triggering of nitric oxide secretion Ejaculation - sympathetic nervous system propels sperm through ducts Resolution - sympathetic signals constrict internal pudendal artery and reduce blood flow to penis

Homework (Self-Review) Define terms: spermatogenesis, dartos muscle, cremasteric muscle, vasectomy, spermiogenesis, ejaculatory duct, inguinale hernia, & cryptorchidism. Trace the pathway of sperm from its formation to ejaculation. Give function(s) of the following: sertoli cell, testosterone, testes, epididymis, seminal vesicle, prostate gland, cowper’s gland, vas deferens, & male urethra. Describe the spermatic cord.