The organs of the male reproductive system include the testes, a system of ducts, accessory sex glands, and several supporting structures, including the scrotum and the penis.
The testes (male gonads) produce sperm and secrete hormones.
Ducts
Epididymis
Vas deferens
Ejaculatory ducts
Urethra
The duct system transports and stores sperm, assists in their maturation, and conveys them to the exterior.
Epididymis (Structure and location)
A tube receiving sperm from the efferent ductules
20 feet long, tightly coiled
Functions of the epididymis
Duct for sperm to pass through on the way out of the body
Site for sperm maturation (1 to 3 weeks)
Secretes small amounts of seminal fluid
Vas deferens (ductus deferens) Structure and location
Extends from epididymis to ejaculatory duct
Has highly muscular walls
Function of the vas deferens
Sperm storage site
Ejaculatory ducts (two)
Formed by the union of the seminal vesicle ducts and the vas deferens
Pass through the prostate gland and terminate in the urethra
Urethra
Serves as a passageway for urine and semen
Seminal vesicles location
Lower posterior bladder
The function of the seminal vesicle
Secrete alkaline, fructose, fibrinogen, and prostaglandins (stimulates contraction, and sperm motility)
Prostate gland location
Just below the bladder
Ejaculatory ducts and urethra pass-through
Function of the prostate gland
Secrete alkaline fluid, clotting enzymes, and citric acid
Bulbourethral glands(Cowper's Gland) location
below the prostate gland
Function of Cowper's gland
Alkaline secretion; lubricant
Scrotum
Internally divided into two compartments, a testis in each
Muscles of the scrotum
Dartos fascia and muscle (Contracts to give a slight elevation of the scrotum)
Cremaster muscle (Significant elevation of testes caused by its contraction, Important since sperm develop at about 3degreesF lower than body temperature)
Penis (external)Structure
Three columns of erectile tissue (blood sinuses in tissue)
Corpora cavernosa (Two upper cylinders)
Corpus spongiosum (One lower cylinder, containing the urethra, External opening of the urethra called the external urinary meatus)
Function of the penis
Erection due to blood flowing into the cavernous tissue faster than it flows out
Spermatic cords (internal)
Between the scrotum and abdominal cavity, in the inguinal canal 2. Contains the vas deferens, nerves, and blood vessels in the testes
Seminal fluid is made of secretions from the following structures:
Testes and epididymis (5% of seminal fluid)
Seminal vesicles (60% of seminal fluid)
Prostate gland (30% of seminal fluid)
Bulbourethral glands (5% of seminal fluid)
Testes (Structure and location)
In the scrotal sac
Spermatic cords
Function of the testes
Provide access for nerves, blood vessels, and vas deferens
Tunica albuginea
Connective tissue around the testis
Extends in as septa dividing the testis into 200 lobules
Each lobule contains the following:
Interstitial cells make testosterone
Seminiferous tubules make sperm
Rete testis
Formed by the uniting of the seminiferous tubules
Efferent ductules
Connect the rete testis to the epididymis
Microscopic anatomy of the testis
1. Interstitial cells produce hormones
2. In spaces between seminiferous tubules
Seminiferous tubules produce sperm
Sertoli cells -supporting cells in seminiferous tubules
Blood-testis barrier formed by Sertoli cells
Prevents the blood from contacting the sperm
If blood did contact sperm, there would be a production of antibodies against the sperm. The male could be sterile.
produce inhibin which stops FSH production
Functions of the testes:
Spermatogenesis (Sperm formation)
Secretion of hormones by interstitial cells
Testosterone function
Promotes "maleness"
Helps regulate metabolism
Plays a part in fluid and electrolyte metabolism
Inhibits secretion of FSH and LH by anterior pituitary
Structure of spermatozoa: Head, middle and tail
Head
1) Contains chromatin
2) Acrosome-covers anterior end and contains hydrolytic enzymes released during capacitation
Enzymes-break down cervical plug
Penetrate the outer covering of the egg
Middle piece
Has mitochondria to produce energy for locomotion
Tail
A flagellum used for locomotion
Capacitation
The process of making the sperm able to fertilize the ovum
Occurs after ejaculation (in the vagina)
Perineum
From the symphysis pubis to the coccyx;
Divided into two triangles formed by drawing a line from ischial tuberosity to ischial tuberosity
Urogenital triangle
The anterior triangle with the external genitalia
Anal triangle - The posterior triangle with the anus