Male Reproductive System III

Question 1

What are efferent ductules?

Answer 1

• lined by simple columnar epithelium w/ ciliated & non ciliated cells
• ciliated cells help move sperm, non-ciliated cells absorb & digest duct fluid (90% resorbed here & head of epididymis)

Question 2

What is the epididymis?

Answer 2

• lined by pseudostratified columnar epithelium w/ stereocilia (for resorption)
• surrounded by circularly arranged smooth muscle fibers
• thickness & number of smooth layers increase from head towards tail
• principal cells function as resorptive & secretory cells
• principal cells are taller inn head than in body & tail
• stereocilia become shorter towards tail

Question 3

How is the sperm reserve depleted in the tail of the epididymis?

Answer 3

• frequent (w/in 1 day) sequential ejaculations will deplete spermatozoal reserves in distal tail of epididymis

Question 4

What is the ampulla?

Answer 4

GLANDULAR PART OF DUCTUS DEFERENS
- terminal part of ductus deferens has numerous pockets, is GLANDULAR & FORMS A MALE ACCESSORY SEX GLAND
- they open into pelvic urethra
- well developed in stallion & Ru

Question 5

What are vesicular glands?

Answer 5

• lined by pseudostratified secretary columnar epithelium & basal cells
• empty into pelvic urethra, in bulls & boar contribute considerably to ejaculate (~30%)
• produce WHITE OR YELLOWISH-WHITE GELATINOUS SECRETION RICH IN FRUCTOSE
• these & other male accessory sex glands ARE HIGHLY (DEHYDRO)-TESTOSTERONE DEPENDENT & shrink in castrated animals

Question 6

What is the prostate gland’s contribution to ejaculate?

Answer 6

• in boars, 35-60%, stallions 25-30%, Ru 4-6%

Question 7

What is prostatic secretion (from prostate gland)?

Answer 7

• contains serous & some mucus secretions
• NEUTRALIZES SEMINAL PLASMA (makes it acidic by accumulation of CO2)
• INITIATES ACTIVE MOVEMENT OF SPERM

Question 8

What are the 2 portions of the topographical prostate?

Answer 8

• body/compact/external portion; surrounds pelvic urethra
• disseminate/internal portion
• histologically both are similar

Question 9

What is the bulbourethral (Cowper’s) gland?

Answer 9

• absent in Ca, well-developed in boar (15-30% contribution to ejaculate)
• mucous & proteinaceous secretion is DISCHARGED BEFORE EJACULATION

Question 10

What does the secretion of the bulbourethral (Cowper’s) gland do?

Answer 10

• neutralizes urethral environment
• lubricates urethra & vagina
• in boar, mucous material is sialic acid rich (gel-like) & possibly involved in occlusion of cervix to prevent sperm loss
  in Fe, mucous material also contains glycogen acting as the energy source in seminal plasma (vesicular glands are absent in Fe, thus no fructose)

Question 11

what is the Flehmen response & vomeronasal organ?

Answer 11

• Flehmen response involves curling of the upper lip so that airflow through the nasal passage is restricted
• sub-atmospheric pressure is thus created in the nasopalatine duct
• hence, fluids can be aspirated through the duct & into the sensory surface of the vomeronasal organ (VNO)
• specialized epithelium of the VNO can sense pheromones

Question 12

What is the anatomical basis of erection?

Answer 12

• shaft of penis has 2 corpora cavernosa & a corpus spongiosum
• arterial blood supply is through dorsal & cavernosal arteries
• corporal sinusoids supplied by helicine arteries
• drain is through deep dorsa vein & superficial dorsal vein
• Eq penis has large corporal sinusoids
• Ru have more fibrous penises
• Os penis in Ca

Question 13

Describe a flaccid penis:

Answer 13

• sinusoids are flattened due to NE release from adrenergic nerves causing constriction
• hence, blood flow to cavernous tissue is low
• in absence of erotogenic stimuli, nonadrenergic noncholinergic (NANC) Parasym neurons do not fire & do not release nitric oxide (NO)
• this leads to vasoconstriction

Question 14

Describe an erect penis:

Answer 14

• when erotogenic stimuli are present, NANC NEURONS FIRE & RELEASE NO
• NO activates guanylate cyclase which converts GTP to cGMP
• this causes relaxation of the smooth muscle of corporal sinusoids (vasodilation)
• cavernous sinusoids engorge w/ blood & intracorporal pressure increases dramatically
• increased pressure compresses the venules which drain blood from the penis
• blood is trapped w/in penis causing an erection

flaccid penis -> sexual arousal (visual, tactile, olfactory) -> vasodilation of helicine arteries (increased blood flow) -> increased blood flow to cavernous tissue & decreased venous outflow -> ejaculation -> venous outflow