Male Reproductive System

Veterinary anatomy

Male Reproductive System

The male reproductive system consists of the

Scrotum Testes Spermatic cord Excurrent duct system

EpididymisDuctus deferenceUrethraAccessory sex glandsPenis

Scrotum

Functions Thermoregulation

Sweat glands Thermosensetive nerves

Protection and support of testis

- The scrotum is a two lobed sack. It protects and supports

the testes and is required for proper temperature regulation.

- The scrotum consists of four major layer. They are: 1) the skin. 2) the tunica dartos

Smooth muscleElevate testes for a sustained period of time in

response to temperature or stress3) the scrotal fascia 4) parietal tunica vaginalis

- The scrotal skin is heavily populated with sweat glands. These sweat glands are required for maintenance of proper testicular temperature. Sweating allows the scrotum to be cooled by evaporative heat transfer.

Scrotum

Descent of testes into scrotumTiming:

Sheep / cattle = midgestation Humans / horses = just before or after

birth

Testes

FunctionsProduce male germ cells (spermatozoa) Produce testosterone, inhibin and estrogen

Testes Structure:Structure:

1. Testicular capsule

2. Parenchyma

3. Mediastinum

4. Rete tubules (rete testis)

5. Efferent ductules

Testes - Structure

1- Testicular capsule

1)Tunica vaginalis Visceral Parietal

2) Tunica albuginea

TestisTestis

Testes - Structure

2- Parenchyma

A- Tubular compartmentSeminiferous tubules

B- Interstitial compartmentLeydig cellsCapillariesLymphatic vesselsConnective tissue

Testes - Structure

3- MediastinumCentral connective tissue core that houses

rete tubules

4- Rete tubules (rete testis)Tiny channels thru which spermatozoa

transported out of testis

Testes - Structure

5. Vasa efferentia (efferent ductules)

a. Collect sperm from rete testis

b. Carry sperm out of testis proper

Testes

Seminiferous tubulesSite of sperm productionConsists of 2 cell types:

Germ cells (eventual sperm cells) Sertoli or nurse cells

Testes

Sertoli cells Surround developing germ cellsProvide structural & metabolic support to

spermatogenic cellsProduces:

Androgen binding protein (ABP) Inhibin Sulfated glycoprotein

Testes

Blood-testis Barriers

a. Cells surrounding seminiferous tubules

b. Prevent autoimmune reaction from destroying developing germ cells

Testes

Leydig cellsLocated between seminiferous tubulesProduce androgens (testosterone)

Epididymis

Three partsHead (caput)Body (corpus)Tail (cauda)

Epididymis - Functions

Sperm Transport MaturationMotilityConcentrationStorageGains ability of fertilization

Vas Deferens

Ductus deferens or deferent ductPaired ducts

Ampulla Wide end of vas deferens

Function Sperm transport from epididymis to pelvic

urethra

Spermatic Cord

- spermatic cord extends from the inguinal ring to it’s attachment on the dorsal pole of the testis. It suspends the testis in the scrotum.

- The function of the spermatic cord is provides the pathway to and from the body for testicular vasculature, Lymphatic and nerves.

Spermatic Cord

- The spermatic cord also houses the ductus deferent, cremaster muscle and specialized vascular network called the pampiniform plexus.

- The pampiniform plexus is a vascular structure

consisting of an intimately intertwined artery and vein and this structure is important for proper temperature control of the testis

Spermatic Cord - Functions

Suspends testis in scrotumPathway to blood vessels, lymphatics, & nervesThermoregulation mechanism

Pampiniform plexus Cremaster muscle

Pulse pressure eliminator

Spermatic CordSpermatic Cord

Accessory Sex Glands

Vesicular glands (seminal vesicles)Prostate glandBulbourethral glands (Cowper’s gland)Ampulla of ductus deference

Vesicular Glands

Paired glandsLocated at junction of urethra & vas deferensRough structureContribute large amount of fluid

Fructose & sorbitol: energy sourcesPhosphate & bicarbonate: buffers

Seminal vesicle

• Absent in camel, dog and cat.• Lobulated type in ox and pig• Vesicular type in horse.

• Shape:• Pyramidal in pig• Elongated and lobulated in ox, sheep and goat• Elongated sac in horse

Prostate Gland

Located caudal to seminal vesicles and close proximity to pelvic urethra

Bilobed in bull

Diffuse in ram

Surrounds urethra in dogs & humans

Function = cleanse & lubricate and secretes just prior during ejaculation

Only accessory gland in dog

Prostate Gland

• The prostate gland of the dog is spherical, smooth and divided into right and left lobes which completely surrounded the urethra.

• In the cat the prostate gland has an uneven surface and covers the urethra dorsally and laterally only.

Bulbourethral Glands

Paired glandsBuried under bulbospongiosus muscleFunction:

Cleanse urethra prior to ejaculation Produce gel fraction Adds considerable volume

Colliculus Seminalis

Region of urethra where sperm mixes with

seminal vesicle secretions

Mixing incomplete in stallion

Sperm-free fraction & Sperm-rich fraction

Comparative of accessory sex gland

AnimalsSeminal vesicle

Ext. prostate Int. prostate

Bulbourethral Ampulla

Horse ++-++

Ox +++++

Sheep&goat +-+++

Camel -++++

Dog -+--+

Cat -++++

Pig ++++-

Penis

Male copulatory organ Consists of

BaseShaftGlans penis

Penis

Cavernous bodies:Corpus spongiosumCorpus cavernosum

Penis

Sigmoid flexure Ram, buck, bullAllows penis to be retracted inside body until

erection occurs

Penis

Retractor penis musclePair of smooth muscleDorsally attached to tail vertebrae Holds penis inside sheath

Glans Distal end of penis, contains sensory nerves

SheathCovers penis

Penis

Two Types1. Fibroelastic

Bull, buck, ram, dog2. Vasomuscular

Stallion, human