Male Urogenital System

about 5 deg. F below core body temperature

At what temperature does spermatogenesis occur?

copulatory organ = deposits semen within the female reproductive tract (Prepuce (sheath) = skin adaptation (penis))

Function of the penis

produce seminal fluid to add bulk to semen (help with sperm swimming)

Function of the prostate (accessory sex glands)

1. Testicular artery and vein (suspended by mesorchium) 2. Deferent duct (suspended by mesoductus deferens)

What 2 structures are found in the vaginal tunic of the male?

a - Ischiourethral m (male) b - constrictor vestibulae m (female) - constricting vestibular bulb

What 3 muscles are responsible for decreased venous outflow during erection?

1. vaginal ring 2. deep inguinal ring 3. superficial inguinal ring

What 3 structures form the inguinal canal?

1. skin 2. Tunica dartos m 3. spermatic fascia (scrotal fascia)

What 3 structures make up the scrotal wall/sac? (first layer)

1. Ampullary glands (ampullar of the ductus deferens) -- glands in the wall that secrete seminal fluid 2. Prostate

What are the 2 accessory sex glands of the dog?

1. bulbus glandis 2. pars longa glandis

What are the 2 parts of the glans of the penis?

1. Root 2. Body 3. Glans

What are the 3 regions of the penis?

1. First stage coitus (male mounts female) 2. The turn (discourages detumescence) - detumescence = swelling of penis - penis twists to keep blood, female holds the bulb 3. second stage coitus (butt to butt) - encourages uterine rather than vaginal insemination whole process takes about 45 min

What are the 3 steps of mating?

1. Ischiourethralis m (not mentioned anywhere else..?) 2. Ischiocavernosus m 3. Bulbospongiosus m 4. retractor penis m

What are the 4 muscles of the urogenital triangle?

- corpus cavernosum penis (cavernous tissue) - surrounded by tunica albuginea (thick, fibrous tunic) - supplied by the deep artery of the penis

What are the R and L crus composed of? What are they surrounded by? Blood supply?

extends from where the 2 crura blend to the glans covering the os penis in the caudal portion of the prepuce

What are the boundaries of the body of the penis?

1. pampiniform plexus 2. ductus (vas) deferens (deferent duct) + corresponding a&v

What are the major components of the spermatic cord?

1. prostate 2. bulbourethral glands -- located at the level of the ischial arch

What are the two accessory sex glands of the tomcat?

1. connects the testis with ductus deferens 2. site of final maturation and storage (tail) of sperm

What are the two major functions of the epididymis (EP)?

1. increases arterial blood inflow 2. decreased venous outflow

What are the two major hemodynamic changes that occur with erection?

1. Intra-pelvic = pelvic urethra -- pre-prestatic and prostatic parts 2. Extra-pelvic = penile (spongy) urethra

What are the two regions of the urethra?

colliculus seminalis

hillock in the middle of the urethral crest - where seminal fluid is collected from the prostate and ampullary glands - where the ductus deferens opens

urethral crest

mucosal ridge that protrudes into the lumen of the cranial part of the pelvic urethra

- originates from aorta - must be ligated in neutering - passes through the inguinal canal

Clinical significance of the testicular artery

dog: horizontal, between the thigh regions tomcat: perineal, tipped or tilted toward the anus (hidden by hair in some cats) (cats and pigs also have hair on their testes but dogs do not)

Difference between location of non-erect penis in dog vs tomcat

vaginal process

Diverticulum of peritoneum present in box sexes

They converge on the dorsal side of the body of the penis and extend side by side throughout the body of the penis to the os penis. - a median septum completely separates the two corpus cavernosum penis - covered by tunica albuginea the whole length - form a groove ventrally that contains the urethra and corpus spongiosum (surrounds the urethra)

Explain how the corpus cavernosum penis of each crus travel along the body of the penis

The DD passes under the ureter as it heads to the prostate gland..... when neutering, if you pull too hard on the spermatic cord, you could tear the ureter

Explain the anatomical relationship of the DD and ureter....clinical significance?

1. Parasympathetic initiates erection - pelvic n 2. Sympathetic initiates ejaculation - hypogastric n 3. Pudendal n branches.... -- sensory = dorsal n of penis -- motor branches allow for contraction of urogenital triangle muscles

Explain the mechanism of erection (nerves/muscles involved)

INSL3 (descendine) secreted by Leydig cells allows the gubernaculum to grow/balloon, increasing abdominal pressure and pulling the testis through the inguinal canal - gubernaculum regresses and leaves two remnant ligaments

Explain the mechanism of testicular decent

both are folds of the visceral vaginal tunic (visceral peritoneum) and communicate with each other as one fold. mesorchium suspends the pampiniform plexus and nerve plexus mesoductus deferens suspends the DD

Explain the relationship between the mesorchium and mesoductus deferens

Transportation of the sperm from the tail of the epididymis to the pelvic urethra, opens into the prostate (continuation of the tail of the epididymis)

Function of the ductus (or vas) deferens (aka - deferent duct)

Origin = caudal border of IAO Skeletal muscle that raises testicles in cold weather close to the trunk Innervation = Genitofemoral n (somatic/voluntary control)

How does the Cremaster m. contribute to testicular thermoregulation? What type of muscle is it, where does it originate from and what nerve is it innervated by?

tomcat = very weak cremaster m.

How does the cremaster muscle differ between dogs and cats?

allows for contact of testicular artery and vein (wraps around the artery) which cools arterial blood

How does the pampiniform plexus contribute to testicular thermoregulation?

Dog : pre-prostatic pelvic urethra = very short Tomcat : long pre-prostatic pelvic urethra 2 - dip in pelvic urethra = colliculus seminals (prostate in that region)

How does the pelvic urethra differ between the dog and tomcat? ID #2

Tomcat = keratinized spines on the penis - induce ovulation in the queen (contact between the spines and the vagina are through to be responsible for the "loud vocalization" made by the queen during mating)

How does the penis in the tomcat differ from the male dog?

- contains sweat glands - no fat within scrotal fascia

How does the scrotum contribute to testicular thermoregulation?

tom: vertical and close to anus (perineal) - also haired dog: horizontal - little to no hair

How does the scrotum/testis differ from the dog vs tomcat?

it is a smooth muscle that involuntarily contracts to tighten scrotum

How does the tunica dartos m. contribute to testicular thermoregulation? What type of muscle is it?

MALE: covers the spermatic cord and is called the vaginal tunic (clinically called the spermatic cord) FEMALE: fat-filled process with round ligament of the uterus, called the vaginal process

How does the vaginal process differ in the male vs female?

exocrine function = spermatogenesis = compromised - needs to be 5 deg F below body temp endocrine function = not affected by temperature (can still produce testosterone)

How is a testicle's exocrine and endocrine functions impacted if they remain inside the abdomen?

1. head of the epididymis 2. body of the epididymis 3. proper ligament of the TESTIS 4. ligament of the tail of the epididymis 5. tail of the epididymis

ID Epididymal regions

1. Artery of the penis (terminates at level of ischial arch as 3 branches....) 2. Artery of the bulb of the penis ---- corpus spongiosum penis and penile urethra 3. Deep artery of the penis ---- corpus cavernosum penis 4. Dorsal artery of the penis --- Glans and prepuce

ID blood supply to the penis... what does each supply?

1,3 = ischiocavernosus muscle - originates from ischiatic tuberosity, covers origin of the crus and inserts distally on the corresponding crus 2 = bulbospongiosus muscle - bulges between the ischiocavernosus muscles, ventral to the external anal sphincter. - fibers are transverse and cover the bulbs of the penis and proximal end of the body of the penis

ID muscles

1. bulbospongiosus m. 2. retractor penis 3. ischiocavernosus m. **all innervated by pudendal nerve (important in errection)**

ID muscles of urogenital triangle..... innervation?

1. bulbus glandis (proximal) - expansile vascular structure responsible for retaining the penis within the vagina during copulation 2. pars longa glandis (distal) - partially encircles the os penis and urethra

ID, functions?

1. parietal vaginal tunic - covered in scrotal fascia 2. visceral vaginal tunic 3. vaginal cavity

Image showing an open castration

retractor penis muscle and external anal sphincter muscle

In the region of the anal sphincter, there is a muscle fiber exchange between what two muscles?

1. Perianal area - look for hernias, masses, and evidence of discharge 2. Anal sac - palpate for impacted or abscessed 3. Prepuce/penis - look for discharge, inflammation, tumors 4. Exposed penis - look for masses, evidence of trauma, color abnormalities 5. Testicles (if intact) - symmetry, size, location

List 5 areas of the external genitalia and perineum region that should be assessed during a physical exam of a male dog...

1. Pampiniform plexus 2. Ductus deferens (+ corresponding sm. a &v) 3. Visceral vaginal tunic - mesorchium = fold covering testicular a&v - mesoductus deferens = fold attaching DD to abdominal and pelvic walls 4. Testicular lymph vessels (scrotum drains separately) 5. Autonomic nn (sympathetic) - inconspicuous

List the 5 contents of the vaginal tunic

1. Cryptorchidism (hidden testis) - testis may remain within the abdomen or inguinal canal 2. Inguinal hernia

List two implications of/clinical significance of testicular descent

1. skin adaptation, protects and supports testis 2. regulates testicular temperature (sweat/sebaceous glands)

Name 2 functions of the scrutum

1. Exocrine function = spermatogenesis 2. Endocrine function = secretion of hormones (Testosterone)

Name 2 functions of the testes

1. Bladder 2. Pelvic urethra 3. Behind the os penis (most common)

Name 3 locations where urinary calculi can get lodged... which is the most common?

1. ductus deferens 2. (testicular a/v) / pampiniform plexus 3. testicle (1 and (2) make up the spermatic cord)

Name 3 structures involved with neutering

1. Cryptorchidism -- unilateral or bilateral (anorchidsm) -- causes = genetic, epigenetic, environmental 2. Phimosis = stenosis of the preputial orifice 3. Hypospadias (rare) = abnormal opening of the urethra due to failure or incomplete closure of the embryonic urethral groove 4. Persistent penile frenulum = failure of the penis to separate completely from the prepuce when animal reaches puberty (important in bulls BSE at 12 mo)

Name 4 developmental anomalies of the male urogenital system

1. Prostatic cyst 2. Prostatic hyperplasia (enlarged prostate gland my impinge on rectum and cause constipation) 3. Penile trauma secondary to paraphimosis (inability to retract penis) 4. Transmissible venereal tumor (Penile TVTs) -- most common tumor, Tx with chemotherapy -- transmitted through intercourse (affects female also - vulva)

Name 4 medical conditions that can be avoided via castration

1. vaginal process (contains round ligament of the uterus) 2. external pudendal a&v 3. genitofemoral n

Name the 3 structures that pass through the inguinal canal in the FEMALE

1. Scrotum 2. Pampiniform plexus 3. Tunica dartos m 4. Cremaster m

Name the 4 structures involved in thermoregulation

1. Vaginal tunic (contains spermatic cord) 2. Cremaster m. 3. External pudendal a&v 4. Genitofemoral n.

Name the 4 structures that pass through the inguinal canal in the MALE

1. os penis 2. urethral groove 3. urethra

Note location of cross section

FALSE!! unilateral = still fertile but not recommended to breed due to high chance of inherited condition (Bilateral cryptorchidism =. infertile)

T or F: An animal with unilateral cryptorchidism is infertile

true

T or F: Keratinized spines of the tomcat regress with castration

FALSE! Cremaster muscle is between the internal and external spermatic fascia

T or F: The cremaster muscle is located within the vaginal tunic

FALSE! - Tom also has an os penis but its is poorly developed (~1/4 inch)

T or F: Tomcats do not have an os penis

level of pars longa glandis 1. os penis (baculum) 2. urethra 3. corpus spongiosum penis

This is a cross section of what level of the penis?

1. Corpus cavernosum (CCP) = PAIRD dorsal bodies surrounded by tunica albuginea penis 2. Corpus spongiosum (CSP) = UNPAIRED ventral body, surrounds spongy urethra and expands distally as the glans

What are the two types of penile erectile tissue? How do they compare/contrast?

results from maximal engorgement of the bulbous glandis caused by pressure from: - engorged female vestibular bulb - constrictor vestibuli and vulvae mm Implications: - the system becomes closed - makes the penis hard and firm and thus capable of intromission and coitus

What causes the coital tie? Implications?

Testes remain in the abdomen - elephants - rhinoceros - seals - crocodiles - whales - dolphins - birds

What does it mean if an animal is a "testicond animal"? Give examples

Ossification of the distal 3-4 inches of the corpus cavernosum penis

What forms the os penis (baculum) and where is it located?

- The right and left crura which originate on the ischiatic tuberosity of each side - root ends where the crura blend with eachother on the midline

What forms the root of the penis? (where does it start and end)

Insulin-like factor 3 (INSL3) = descendine - produced by Leydig cells (also produce testosterone in testis)

What induces growth of the gubernaculum testis?

vaginal cavity (extension of the peritoneal cavity)

What is the 3rd layer of the scrotum/testicle?

- bilobed dorsal expansion of the corpus spongiosum penis that surrounds the urethra - located between the crura - supplied by artery of the bulb

What is the bulb of the penis and where is it located? Blood supply?

used to pexy the bladder to the body wall in perineal hernias to prevent bladder retroflexion

What is the clinical relevance of the ductus deferens?

Ureter opens into the bladder, if there is an infection in the bladder it may translate to infection in the penis or prostate

What is the clinical significance of the genital and urinary tracts being connected?

left gonadal v = more caudal, drains into L renal v right gonadal v = more cranial, drains into caudal vena cava

What is the difference between the left and right gonadal veins?

the sheath of skin surrounding and protecting the penis

What is the prepuce?

constrictor vestibuli/vulvae (constricts around bulbous glandis)

What is the structure from the female that relates to the coital (copulatory) tie?

Cut through skin and tunica dartos, then peel the testicles out from the scrotal fascia (leave testicle inside the parietal vaginal tunic)

What layers do you cut through for a closed castration?

cut through skin, tunica dartos, scrotal fascia AND parietal vaginal tunic -- risk infection

What layers do you cut through for an open castration? implications?

parietal vaginal tunic

What makes up the parietal peritoneum of the scrotum/testicles? (second layer)

Tunica albuginea testis = testicular capsule

What makes up the testicular capsule (5th layer) of the scrotum/testicular layers

Visceral vaginal tunic

What makes up the visceral peritoneum (4th layer) of the scrotum/testicle layers?

Urethralis m (skeletal) -- becomes bulbospongiosus muscle Innervation = pudendal nerve Function = voluntary control of urine

What muscle (+type) surrounds the pelvic urethra? Innervation? Function?

muscles of the urogenital triangle... -- bulbospongiosus m. (spazmatic contractions push on urethra) -- retractor penis -- ischiocavernosus m. (rhythmic contractions increase penile intra-cavernous pressure) Push on the urethra when they contract which increases pressure All innervated by the pudendal n.

What muscles are linked to erection/ejaculation and how so? innervation?

dorsal nerve of the penis (sensory branch of pudendal n)

What nerve is responsible for sensation to the glans penis?

Pelvic n = erection (parasympathetic) Hypogastric n = ejaculation (sympathetic)

What nerves are responsible for erection and ejaculation?

1. Bulbourethral glands at ischial arch 2. Retractor penis m

What serves as the landmark for a perineal urethrostomy in a tomcat?

the vaginal ring

What structure does the ductus deferens pass thru before reaching the bladder?

Gubernaculum testis

What structure is responsible for testicular descent?

FEMALE = vaginal process + round ligament of the uterus MALE = vaginal tunic + spermatic cord

What structures pass through the inguinal canal in the male vs female?

1. Proper ligament of the testis 2. Ligament of the tail of the epididymis

What two ligaments are remnants of the gubernaculum testis?

starts aprox. day 3 after birth and is complete by aprox. day 10 after birth

When does testicular descend occur normally in dogs?

on either side of the colliculus seminalis (eminence in the prostate) - dump contents into urethra

Where do the ductus deferens terminate?

behind the kidneys (descend to the scrotum after birth)

Where do the testes develop during fetal life?

behind the os penis

Where is the most common location of a urethral obstruction (stone) in the male dog?

at the tip of the penis = urethral plug - distended urinary bladder - hemorrhages on the surface of the bladder

Where is the most common location of a urethral obstruction (stone) in the tomcat? What secondary effects does this have on the bladder?

because the diameter of the lumen of the urethra widens at the ischial arch

Why is a perineal urethrostomy performed at the ischiatic arch rather than another location along the urethra?

bulbous glandis

____________ becomes engorged with blood during erection

1. scrotum 2. anus 3. ischiocavernosus m. (covering crura of penis) 4. retractor penis 5. bulbospongiosus m.

what is #3 covering?