Scrotum & Testicle

Scrotum

A.  Function

            Thermoregulation/radiation, protection, and support of testis

B.  Thermoregulation Mechanism

Sweat glands and thermosensetive nerves are involved

C.  Scrotum layers

1.  Skin

1. Tunica dartos (dartos muscle)
   - Smooth muscle

- Elevate the testes for a sustained period of time in response to temperature or stress

3.  Scrotal fascia

4. Parietal and visceral tunica vaginalis

5. Tunica Albugania

- Closely related with secretory tissues of testicle

D.  Descent of Testes into Scrotum

1.  Inguinal canal

2.  Gubernaculum

3.  Inguinal hernia

4.  Tunica vaginalis formed

5.  Timing:

a.  Sheep/cattle = midgestation

b.  Swine = last 1/3 of gestation

c.  Humans/horses = just before or after birth

Testicle

A.  Functions

1.  Produce male germ cells (spermatozoa)

2.  Produce male hormone (testosterone)

3. Produce inhibin and estrogen, and other proteins

B.  Structure

1.  Tunica vaginalis

a.  Thin membrane

b.  Provides support

c.  From peritoneum

2.  Tunica albuginea

a.  Connective tissue

b.  Provides structure

3.  Mediastinum

a.  Connective tissue

1. Provides internal support
   4.  Seminiferous tubules
   part of the testicular parenchyma
   a.  Site of sperm production
   b. Consists of 2 cell types 
   - Germ cells (eventual sperm cells)
   - Sertoli or nurse cells which produces variety of substances including androgen binding hormone, sulfated glycoprotein, transferin, and inhibin
   - Surround developing germ cells
   - Providing structural and metabolic support to the developing spermatogenic cells
   
   
   3.  Blood-testis Barriers
   a. Cells surrounding the seminiferous tubules
   b. Prevent autoimmune reaction from destroying the developing germ cells
   5.  Interstitial or Leydig cells
   a.  Located between seminiferous tubules
   b.  Produce androgens (testosterone)
   6.  Rete testis
   a.  Collect sperm from seminiferous tubules
   7.  Vasa efferentia (efferent ductules)
   a.  Collect sperm from rete testis
   b.  Carry sperm out of testis proper