Transverse Section (T.S.) of Mammalian Testis

The mammalian testis is a crucial organ in the male reproductive system, primarily responsible for the production of sperm (spermatogenesis) and the secretion of hormones like testosterone. A transverse section (T.S.) reveals its detailed internal structure, which is organized into compartments and contains various cell types.

Key Structures Visible in a T.S. of Testis:

1. Tunica Albuginea: This is the outer, tough, fibrous protective covering of the testis. It is made of dense connective tissue and provides structural integrity.

2. Septa: Extending inward from the tunica albuginea are fibrous partitions called septa. These divide the testis into about 200-300 wedge-shaped lobules.

3. Seminiferous Tubules: Each lobule contains 1-3 highly coiled tubes called seminiferous tubules. These are the functional units where sperm production occurs. The tubules are lined with a complex stratified epithelium called the germinal epithelium, which consists of two main cell types:

Spermatogenic cells: These cells undergo division and differentiation to form spermatozoa (sperm). They are arranged in layers from the basement membrane towards the lumen:
- Spermatogonia (stem cells)
- Primary Spermatocytes
- Secondary Spermatocytes
- Spermatids
- Spermatozoa
Sertoli cells (Sustentacular cells): These are large, columnar cells that extend from the basement membrane to the lumen. They provide nourishment, support, and protection to the developing sperm cells. They also form the blood-testis barrier, which creates a privileged environment for meiosis.

4. Interstitial Cells (Leydig cells): Located in the connective tissue between the seminiferous tubules, these cells are responsible for the synthesis and secretion of the hormone testosterone, which is essential for sperm production and the development of male secondary sexual characteristics.

5. Rete Testis: The seminiferous tubules open into a network of channels called the rete testis, which is located at the posterior side of the testis. This serves as a collection area for sperm before they move into the epididymis.

6. Blood Vessels and Nerves: The connective tissue stroma contains a rich supply of blood vessels and nerves that nourish the organ and regulate its function.

Process Occurring Inside:

The entire process of spermatogenesis (sperm formation) takes place within the seminiferous tubules. It begins with mitotic divisions of spermatogonia, followed by meiosis in spermatocytes, and finally spermiogenesis (maturation of spermatids into spermatozoa). The mature sperm are released into the lumen of the tubule.

Related Topics:

Male Reproductive System: Understanding the testis is key to the overall male reproductive anatomy, which includes structures like the epididymis, vas deferens, and accessory glands.

Spermatogenesis: This is the detailed process of sperm formation, involving cellular divisions and differentiation within the seminiferous tubules.

Endocrine Function: The testis also acts as an endocrine gland, primarily through Leydig cells producing testosterone, which regulates various bodily functions.

Important Formulae (Hormonal Regulation):

The function of the testis is regulated by hormones from the pituitary gland. The key hormonal axis involves:

$GnRH \to LH \to Testosterone$

$GnRH \to FSH \to Spermatogenesis$

Where GnRH (Gonadotropin-Releasing Hormone) from the hypothalamus stimulates the anterior pituitary to release LH (Luteinizing Hormone) and FSH (Follicle-Stimulating Hormone). LH acts on Leydig cells to produce testosterone, and FSH acts on Sertoli cells to support sperm production.