Male Reproductive System Veterinary anatomy

Male Reproductive System The male reproductive system consists of the Scrotum Testes Spermatic cord Excurrent duct system Epididymis Ductus deference Urethra Accessory sex glands Penis

Scrotum Functions Thermoregulation Sweat glands Thermosensetive nerves Protection and support of testis

The scrotum is a two lobed sack 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 muscle Elevate testes for a sustained period of time in response to temperature or stress 3) 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 scrotum Timing: Sheep / cattle = midgestation Humans / horses = just before or after birth

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

Testes Structure: Testicular capsule Parenchyma Mediastinum Rete tubules (rete testis) Efferent ductules

Testes - Structure 1- Testicular capsule 1)Tunica vaginalis Visceral Parietal 2) Tunica albuginea

Testis

Testes - Structure 2- Parenchyma A- Tubular compartment Seminiferous tubules B- Interstitial compartment Leydig cells Capillaries Lymphatic vessels Connective tissue

Testes - Structure 3- Mediastinum Central 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 tubules Site of sperm production Consists of 2 cell types: Germ cells (eventual sperm cells) Sertoli or nurse cells

Testes Sertoli cells Surround developing germ cells Provide structural & metabolic support to spermatogenic cells Produces: 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 cells Located between seminiferous tubules Produce androgens (testosterone)

Epididymis Three parts Head (caput) Body (corpus) Tail (cauda)

Epididymis - Functions Sperm Transport Maturation Motility Concentration Storage Gains ability of fertilization

Vas Deferens Ductus deferens or deferent duct Paired 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 scrotum Pathway to blood vessels, lymphatics, & nerves Thermoregulation mechanism Pampiniform plexus Cremaster muscle Pulse pressure eliminator

Spermatic Cord

Accessory Sex Glands Vesicular glands (seminal vesicles) Prostate gland Bulbourethral glands (Cowper’s gland) Ampulla of ductus deference

Vesicular Glands Paired glands Located at junction of urethra & vas deferens Rough structure Contribute large amount of fluid Fructose & sorbitol: energy sources Phosphate & 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 glands Buried under bulbospongiosus muscle Function: 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 Ampulla Bulbourethral Int. prostate Ext. prostate Seminal vesicle Animals + - Horse Ox Sheep&goat Camel Dog Cat Pig

Penis Male copulatory organ Consists of Base Shaft Glans penis

Penis Cavernous bodies: Corpus spongiosum Corpus cavernosum

Penis Sigmoid flexure Ram, buck, bull Allows penis to be retracted inside body until erection occurs

Penis Retractor penis muscle Pair of smooth muscle Dorsally attached to tail vertebrae Holds penis inside sheath Glans Distal end of penis, contains sensory nerves Sheath Covers penis

Penis Two Types 1. Fibroelastic Bull, buck, ram, dog 2. Vasomuscular Stallion, human