5 – Male Reproduction III

Question 1

Efferent ductules

Answer 1

• Lined by simple columnar epithelium w/ciliated and non-ciliated cells
• Ciliated cells: help move sperm
• Non-ciliated cells; absorb and digest duct fluid (90% reabsorbed in here and head of epididymis)

Question 2

Epididymis

Answer 2

• Lined by pseudostratified columnar epithelium with stereocilia
• Surrounded by circularly arranged smooth muscle fibers
• THICKNESS AND NUMBER OF SMOOTH LAYERS INCREASE FROM HEAD TO TAIL
• Principal cells

Question 3

Principal cells (epididymis)

Answer 3

• Resorptive and secretory cells
• Taller in head than body and tail

Question 4

Stereocilia (epididymis)

Answer 4

• Become shorter towards tail
• For reabsorption

Question 5

Depletion of sperm reserve in tail of epididymis

Answer 5

• Frequent sequential ejaculations DEPLETE spermatozoa reserves in distal tail of epididymis

Question 6

Ampulla

Answer 6

• Glandular part of ductus deferens (terminal part)
• Numerous pockets
• Glandular
• Forms male accessory sex gland
• Open into pelvic urethra
• Stallion and ruminants

Question 7

Vesicular glands

Answer 7

• Lined by pseudostratified secretory columnar epithelium and basal cells
• Empty into pelvic urethra (bulls and boars) and contribute to ejaculate (30%)
• Produce white or yellowish-white gelatinous secretion rich in FRUCTOSE
• Highly (dehydro)testosterone dependent and SHRINK in CASTRATED animals

Question 8

Prostate gland contribution to ejaculate

Answer 8

• Boars: 35-60%
• Stallions: 25-30%
• Ruminants: 4-6%

Question 9

Prostatic secretion

Answer 9

• Contains serous and some mucous secretions
• NEUTRALIZES seminal plasma (makes it acidic by accumulation of CO2)
• Initiates active movement of sperm

Question 10

2 portions of prostate

Answer 10

• Body/compact/external portion: surrounds pelvic urethra
• Disseminate/internal portion
• *histologically both are similar

Question 11

Bulbourethral gland

Answer 11

• Absent in dogs
• Well developed in boar (15-30%)
• Mucous and proteinaceous secretion is discharged BEFORE ejaculation

Question 12

Mucous and proteinaceous secretion is discharged BEFORE ejaculation

Answer 12

• Neutralizes urethral environment
• Lubricates urethra and vagina
• Boar: sialic acid rich, possible involved in occlusion of cervix to prevent sperm loss
• Cat: mucous material contains glycogen acting as energy source in seminal plasma
  o No vesicular glands=no fructose

Question 13

Flehmen response

Answer 13

• Curling of upper lip so that AIRFLOW thru the nasal passage is restricted
• Sub-atmospheric pressure created in nasopalatine duct
• Fluids can be aspirated thru the duct and sensory surface of vomeronasal organ
• Specialized epithelium of VNS can sense pheromones

Question 14

Anatomical basis of erection

Answer 14

• 2 corpus carvernosum and a corpus spongiosum
• Arterial blood supply is thru DORSAL and cavernosal arteries
• Drain thru deep dorsal vein and superficial dorsal vein
• Horse penis: large sinusoids
• Ruminants: fibrous penis
• Dogs: os penis

Question 15

Flaccid penis

Answer 15

• Sinusoids flattened due to NE release from adrenergic nerves causing constriction
• Blood flow to cavernous tissue is low
• If no erotogenic stimuli=PS neurons do NOT fire=do not release NO
• *leads to vasoconstriction

Question 16

Erect penis

Answer 16

• Erotogenic stimuli are present=NANC (nonadrenergic noncholinergic) neurons fire and release NO
  o GTP converted to cGMP (by guanylate cyclase)
• Relaxation of smooth muscle of sinusoids (vasodilation)
  o Engorge with blood and increase pressure which compresses venules=blood trapped within penis=erection