THE REPRODUCTIVE SYSTEM
GYNECOLOGY - A branch of medicine that deals with the diseases and hygiene of women.
UROLOGY - A branch of medicine dealing with the urinary or urogenital organs, dx and tx of the disorders of the male reproductive system.
MALE REPRODUCTIVE SYSTEM:
A. ANATOMY
a. Primary reproductive organ: Testes (sing., testis)
b. Accessory reproductive structures: ducts or glands that aid in the delivery of the sperm.
1. TESTES - male gonads; paired oval glands, measuring about 4 - 5 cm. (2in) long and 2.5 cm in diameter
- Surrounded by the TUNICA VAGINALIS - serous membrane derived from the peritoneum and forms during the descent of the testes; partially covers the testes.
- TUNICA ALBUGINEA - extensions plunge into the testis and divides it into lobules which contain the seminiferous tubules; internal to the tunica vaginalis.
- SEMINIFEROUS TUBULES: "sperm producing factories"
- drains into the rete testis
- 2 types of cells in the S.T.
a. SPERMATOGENIC CELLS - sperm - forming cells.
b. SERTOLI CELLS - have several functions in supporting spermatogenesis.
- INTERSTITIAL CELLS OF LEYDIG/ Interstitial Cells/ Cells of Leydig: lies in the soft connective tissue surrounding the seminiferous tubules; produces androgens, importantly, testosterone.
- RETE TESTIS: network of ducts in the testis
- Empties into network of about 15 - 20 tubules called EFFERENT DUCTULES
- EPIDIDYMIS: first part of the duct system which hugs the external surface of the testis
** CRYPTORCHIDISM -
2. DUCT SYSTEM
A. EPIDIDYMIS
- comma - shaped organ on the posterior part of the testes measuring about 4 cm (1.5 in.) long
DUCTUS EPIDIDYMIS - tightly coiled part of the epididymis
3 PARTS: Head - larger superior portion of the epididymis
Body - Narrow, midportion
Tail - Smaller, inferior portion
- caps the superior part of the testis and runs down its posterolateral side
- temporary storage site for the sperm cells which comes from the testis
- site where they acquire motility and the ability to fertilize an ovum
- During sexual stimulation the walls of the epididymis contract to expel sperm
B. DUCTUS DEFERENS/ VAS DEFERENS
- ~ 45 cm long
- Emerges from the epididymis and ascends along the posterior aspect of the testis and passes through the inguinal canal into the pelvic cavity and arches over the superior aspect of the bladder.
- Enclosed in a connective tissue sheath called the SPERMATIC CORD
- Ends in an AMPULLA which joins the duct of the seminal vesicle to form the EJACULATORY DUCT
- Main Function: To propel live sperm from the storage sites, epididymis and distal part of the ductus deferens into the urethra.
- During Ejaculation: peristaltic waves made by the walls of the smooth muscles squeeze the sperm forward.
- Cut during VASECTOMY.
C. URETHRA - a shared terminal duct of the reproductive and urinary systems in males.
- extends from the base of the urinary bladder to the tip of the penis
- terminal part of the male duct system
- Three Regions:
c.1. Prostatic Urethra -
c.2. Membranous Urethra -
c.3. Spongy or Penile Urethra -
- during ejaculation, the bladder sphincter constricts
3. ACCESSORY GLANDS AND SEMEN
a. Seminal Vesicles - aka seminal glands
- Convoluted, pouchlike structures about 5 cm(2 in) in length
- Located at the base of the bladder which produces about 60% of the fluid volume of semen
- Secretes a thick yellowish secretion rich in fructose, Vit. C, prostaglandins which nourish and activate the sperm.
- Alkaline in nature
- The duct of the seminal vesicle joins the ampulla of the ductus deferens to form the ejaculatory duct.
b. Prostate Gland - ~ 4 cm in diameter and 3 cm in length
- Single gland, about the shape of the chestnut which encircles the prostatic part of the urethra and the 2 ejaculatory ducts
- Secretes a milky fluid substance, which helps activate the sperm - contribute to sperm motility and viability.
- Enters the urethra through several small ducts.
c. Bulbourethral Glands/ Cowper's Gland
- Tiny pea sized glands inferior to the prostate gland
- Produces thick clear mucus that drains to the penile urethra.
- DURING SEXUAL EXCITATION:
d. Semen - milky white mixture of sperm and accessory gland secretions.
- Provides a transport medium and nutrients and chemicals that protect the sperm and aid in their movement.
- Alkalinity of the semen helps in the neutralization of the acid environment of the female vagina.
- Dilutes the sperm, which promotes sperm motility.
4. EXTERNAL GENITALIA
A. Scrotum -
Maintains the temperature of the testes at 2 - 3oC lower than body temperature.
- 2 muscles that elevates the testes:
a. Dartos Muscle - wrinkles the skin of the scrotum and elevates the testis
b. Cremaster Muscle - moves the testes closer to the pelvic cavity
B. Penis
- Delivers the sperm to the female reproductive tract
Parts: B.1. Root of the Penis
B.2. Body of the Penis
B.3. Glans Penis
- Prepuce or Foreskin - covers the glans penis; removed in circumcision
- During erection, the three elongated areas of erectile tissue surrounding the spongy urethra is filled(engorged) with blood.
- helps the penis to act as penetrating organ in the delivery of the semen into the vaginal canal.
- CIRCUMCISION - the surgical removal of a part or the entire prepuce.
II. MALE REPRODUCTIVE FUNCTIONS:
1. SPERMATOGENESIS
- takes about 65 - 75 days
- Begin with the spermatogonia which contain a diploid number of chromosomes (2n)
- Spermatogonia undergo mitosis to produce two daughter cells
PRIMARY SPERMATOCYTE - undergoes meiosis
- SPERMIOGENESIS - the final stage of spermatogenesis
2. TESTOSTERONE PRODUCTION
- sometimes known as " musculinizing hormone"
- produced by the interstitial cells of Leydig
- During puberty, interstitial cells are activated by the LH, aka ICSH, which is relesed by the anterior pituitary gland.
- From this time on, the interstitial cells produce testosterone throughout a man's life
- ACTIONS of testosterone:
a. stimulates reproductive organs to develop to their adult size
b. Underlies the sex drive
c. Causes the male secondary sexual characteristics to appear
c.1. Deepening of the voice
c.2. Increased hair growth all over the body
c.3. Enlargement of the skeletal muscles
c.4. Increased heavines of the skeleton
d. Needed for sperm maturation
SEXUAL INFANTILISM:
