TESTIS

Location: within the scrotum were the temperature is 2-3^oC below body temperature.

Function: production of sperm and secretion of androgens.

Composition: 250 lobules with 1-4 seminiferous tubules and connective tissue stroma with Leydig cells and intratesticular ducts.

Capsule

Function: protection

Composition:

• Tunica vaginalis, the extension of the peritoneum, simple squamous epithelium - mesothelium and small amount of loose connective tissue
• Tunica albuginea - thick fibrous connective tissue
• Tunica vasculosa - loose connective tissue that contains blood vessels

SEMINIFEROUS TUBULES

Composition:

• Tunica propria (lamina propria), some layers of myoid cells (peritubular contractile cells), collagen fibers, and basal lamina

Function: contraction

• Seminiferous epithelium is composed of two basic cell populations on the basal lamina:

• Sertoli cells (supporting or sustentacular cells) that contain characteristic inclusion bodies.

Function: supporting cells for the developing sperm, exchange of metabolic substrates and wastes between the developing spermatogenic cells and the circulatory system, exocrine secretion of androgen-binding protein, endocrine secretion of inhibin.

• Spermatogenic cells, they regularly replicate and differentiate into mature sperm

Location: between Sertoli cells

• Type A dark (Ad) spermatogonia, stem cells, undergo mitosis.
• Type A pale (Ap) spermatogonia are committed to the differentiation, undergo several mitotic divisions.
• Type B spermatogonia, ubdergo several mitotic division.
• Primary spermatocytes - undergo first meiotic division that results in reduction of number of chromosomes.
• Secondary spermatocytes enter the second meiotic division without synthesizing new DNA.

• Spermatids, the haploid sells, undergo a maturation process (spermiogenesis).

• Sperm, mobile cells, contain acrosomal cap in the head, what is essential for penetration of the ovum, and tail.

Location: in connective tissue stroma.

Function: epithelioid androgen, steroid-secreting cells.

TUBULI RECTI AND RETE TESTIS

Location: vascular connective tissue of mediastinum, the project of tunica albuginea.

Composition: Simple cuboidal or columnar epithelium on basal lamina.