Comparative Male Repro Anatomy (Mod. 5)

Ruminant Repro Anatomy

What “type” of penis is the ruminant penis? (and in this case, the boar penis as well)

Type: Fibroelastic penis

• Has the same basic anatomy as the other species -

  • Has two crura of corpus cavernosum, forming the body of penis

  • Corpus spongiosum surrounds urethra… runs down penis and forms glans

HOWEVER, has a couple different notable features:

• The “blood spaces” (cavernous tissue) are much smaller than in the musculocavernous type penis

• Mainly composed of fibroelastic tissue (particularly in the tunica albuginea)

  • Maintains some rigidity even when not erect

The combo of fibroelastic tissue + small cavernous spaces means only a SMALL AMOUNT OF BLOOD is needed for erection… is very rapid

• Penis is also much more narrow than the musculocavernous type

What is the sigmoid flexure?

The sigmoid flexure is a bend in the body of the penis

• Is found ventral to the pelvis, within the body

When the penis is NOT erect, the body is “thrown” into a sigmoid flexure conformity and is drawn into the prepuce

• During erection, blood flowing into the cavernous spaces straightens out the flexure

Function: draws penis into prepuce when not erect

What are the 5 different penile muscles, and what are their functions? (the same as all of the others, but have different conformities)

1) Paired retractor penis muscles

• Attaches at second bend in sigmoid flexure (makes sense… structure = function)

• Maintains the sigmoid flexure

2) Urethralis:

• Wraps around the urethra

3) Bulbospongiosus muscle

• Accompanies urethra over ischial arch (see image)

4) Ischiocavernosus muscle

• Surrounds crura

5) Ischiourethralis muscle

• Controls the fibrous ring surrounding the dorsal vein that drains the penis

Describe the erection process of the fibroelastic penis…

Again, is rapid because of the small cavernous spaces and already rigid fibroelastic tissue

BUT is the same 2 stage process as canine and equine erection

1) Increased blood in cavernous spaces, bringing up blood pressure

2) Ischiocavernosus muscle contracts, bringing up blood pressure ABOVE arterial pressure in the cavernous spaces; also venous occlusion

• Straightens sigmoid flexure

Okay, now SPECIFICALLY about the ruminant penis… describe the glans penis, and the differences between bulls and rams…

The glans penis of BOTH is small and soft, slightly cone shaped with ventral deviation of tip. HOWEVER:

• Small ruminants - have a distinct extension called the urethral process

  • Looks like a little hair ***** BIG defining feature, remember for PSQ

• Big ruminants - Have an atypical ligament which causes a slight left spiral of the glans… if severe, can cause fertility issues

Describe the ruminant prepuce (just very basic…)

Is “long and narrow”, mimicking the shape of the penis

Is looser caudally to allow for protrusion of penis

Is the little belly button looking thing on the cow… not the umbilicus. peen.

Describe the ruminant testes… very basic, but also describe the orientation of the epididymis

Testes:

• Proportionally large, rounded, and plump

• For some reason, small ruminants have proportionally larger testes than larger ruminants

• Vertically oriented?? (OH WAIT like the oval goes up down… this is different in stallions, where their’s are horizontal)

• Testicular capsule is tortuous… can see curvy vessels on surface

Epididymis:

• Tail - Projects ventrally at bottom of testes

  • VAS DEFERENS ORIGINATES HERE… runs up to join the spermatic cord

• Body - Runs around the caudo-medial side, then doubles back over

• Head - Extends over free border of testes, then doubles back and down

Describe the ruminant scrotum… again, super basic

Pendulous (that shit swangin)

Has a median groove as well

Narrows at the junction with body wall

• Caudal to superficial inguinal ring

• Can have a deposition of fat called “cod fat” around the spermatic cord at the neck

Thin skin of scrotum is firmly attached to underlying dartos

What is the “rudimentary teat” on the scrotal tissue?

A “false teat” on the cranial face of the scrotum

What are the characteristics of the 4 main accessory glands in the bull and ram?

1) Ampulla

• Bull: 10-12 cm, visible but smaller than the stallion’s

• Ram: about 5 cm

2) Seminal vesicle

• Bull: Paired, large; irregular, lobulated surface; produces the bulk of seminal tissue

• Ram: ^^^

3) Prostate

• Bull: Compact part and a lot of diffuse prostatic tissue within the wall of the urethra

• Ram: Diffuse prostatic tissue ONLY, no compact prostate

4) Bulbourethral glands

• Bull and Ram: Small and flattened; paired

In ruminants, when do the balls drop? And what are 4 unique features of the ruminant neonate?

Testes descend DURING GESTATION…

• At time of birth, should be descended

Features of the neonate penis:

1) Initially slender and short at birth

2) NO SIGMOID FLEXTURE
3) Has an initial attachment of prepuce to the tip of the penis by a frenulum (see image)… also like this in carnivores

4) The quick lengthening of the penis is what develops the sigmoid flexure