Lecture 40 - Male reproductive system

Question 1

testes

Answer 1

o Divided into approximately 250 lobules by connective tissue septa
o Each lobule contains 3 - 10 seminiferous tubules
o Each tubule forms a highly convoluted loop within lobule
o Tubules end as straight tubule (tubulus erectus) at mediastinum
o Connected to rete testis (anastomosing channel system)

Question 2

layers around the testis

Answer 2

o Tunica vaginalis: during decent, extension of abdominal peritoneum
o Tunica albuginea: dense connective tissue capsule

Question 3

testicular decent

Answer 3

o Gonadal development occurs along posterior abdominal wall
o Testes desend towards inguinal canal by 7 months gestation
o Through inguinal canal into scrotum just before birth
o Drags blood vessels, nerves, duct system and layers of abdominal wall into scrotum

Question 4

Cryptorchidism (undescended testes) (hidden testis)

Answer 4

o Histological changes – infertility
o Increased risk of testicular cancer
o Needs to be surgically corrected preferentially before 18 months/2 years of age

Question 5

epididymis

Answer 5

o About 5m long, highly coiled
o Consist of caput (head), corpus (body) and caudal (tail) segments
o Surrounded by smooth muscle cells
o Storage and maturation of sperm

Question 6

vas deferens (ductus deferens)

Answer 6

o Penetrates abdominal wall through inguinal canal
o Descends along lateral wall of pelvic cavity
o Meets duct of seminal vesicle to form ejaculatory duct
o Muscular duct (smooth muscle wall) which transports spermazoa to ejaculatory duct
o Part of spermatic cord
o Ejaculation mediated by sympathetic nervous system

Question 7

vasectomy

Answer 7

Involves ligating duct to prevent sperm from reaching penis

Question 8

accessory glands

Answer 8

o Contribute to volume of ejaculate
o Each has different secretion with different functions
o Seminal vesicles, prostate, bulbourethral glands

Question 9

seminal vesicles

Answer 9

o Posterior surface of bladder
o Ducts of seminal vesicles join vas deferens to form ejaculatory duct, which empties into prostatic urethra
o Contribute to volume of semen
o Secretes alkaline, viscous fluid (55-61% of seminal fluid) - neutralization of acidic female reproductive tract environment
o Contributes to sperm motility and viability

Question 10

prostate

Answer 10

o Inferior to bladder – anterior to rectum – superior to pelvic diaphragm – surrounds urethra
o Approximately size of walnut

Question 11

prostate

Answer 11

o function Secretion (~30-35% of semen): watery liquid containing zinc, citric acid, prostaglandins, and proteolytic enzymes (slightly acidic)
o One component: prostate specific antigen - liquifies semen (helps movement of sperm)
o Muscles help move seminal fluid into urethra Acts as valve, ensures the right fluid flows at the right time – urination or ejaculation

Question 12

Benign prostatic hypertrophy

Answer 12

o Occurs in most elderly men
o Hypertrophy of prostate
o Compresses urethra and can eventually block it entirely
o DRE reveals “bulky” prostate

Question 13

prostate cancer

Answer 13

o Common malignancy in men
o 70% are in peripheral region
o Diagnosed by DRE (feels rock hard) and blood tests
o Can be treated by radiotherapy, chemotherapy or removal

Question 14

Bulbourethral glands = Cowper’s gland

Answer 14

o Paired, pea-shaped
o In deep perineal pouch
o Duct opens into spongy urethra
o Mucous type secretion
o To lubricate urethra
o Forms pre-ejaculate

Question 15

hypospadias

Answer 15

o Congenital disorder of the penis
o Urethra opens somewhere along the shaft of the penis
o Occurs in approximately 1:250 boys at birth (increasing)

Question 16

External genitalia

Answer 16

o Erectile tissues covered by skin
o Body of penis is pendulous and entirely surrounded by skin
o Scrotum = homologue of labia majora. The skin fuses in midline = raphe
o Testes descend into this pouch
o Skin over glans penis = prepuce is open anteriorly and attached to glans at the frenulum

Question 17

penis

Answer 17

o Perineal membrane and pubic arch = attachment for roots of penis
o Erectile tissues: two corpora cavernosa and a single corpus spongiosum
o Corpus spongiosum expands distally to form glans penis
o Urethra pierces perineal membrane, enters corpus spongiosum, and opens at glans penis

Question 18

Erectile tissues in male and female

Answer 18

o Two corpora cavernous (male and female)
o A single corpus spongiosum (male) and two bulbs of vestibule (female)

Question 19

Penis erection

Answer 19

o Erection is mediated by parasympathetic nervous system, which relaxes arteries in penis, allowing blood to fill erectile tissues
o Ischiocavernosus and bulbospongiosus muscles move blood from root into body of penis and constrict venous drain