Testes - Anatomy and Functions

The testes are a pair of oval-shaped endocrine glands present in the male reproductive system. They are the primary male reproductive organs and play a dual role by producing male gametes (sperms) and secreting hormones. The testes are essential for reproduction and the development of male secondary sexual characteristics.

Characteristics of the Testis

• The testes are located in the scrotum, outside the abdominal cavity.
• It is present as a pair, one on each side.
• Each testis is oval in shape.
• It is covered by a tough fibrous layer called the tunica albuginea.
• It is maintained at a temperature slightly lower than body temperature (important for sperm production).

Structure of the Testis

The testes are oval-shaped organs, each about 4–5 cm long and 2–3 cm wide. Usually, the left testis hangs slightly lower than the right.

Coverings of the Testis

Each testis is covered by three protective layers:

1. Tunica vaginalis: Outer covering and double-layered membrane that reduces friction
2. Tunica albuginea: Thick, fibrous middle layer that divides the testis into compartments called lobules
3. Tunica vasculosa: Inner vascular layer, rich in blood vessels supplying the testis

Internal Structure

Each testis contains numerous coiled structures and ducts involved in sperm production and transport.

• Seminiferous Tubules: Highly coiled tubes present inside each lobule and are the site of sperm production (spermatogenesis). Sertoli cells and germ cells are present inside the seminiferous tubules, while Leydig cells are located in the interstitial spaces between the tubules and produce testosterone.
• Rete Testis: A network of tubules connecting the seminiferous tubules, collects sperm and transports them forward, and absorbs excess fluid to concentrate sperm
• Efferent Ducts: They carry sperm from the rete testis to the epididymis and also help in fluid absorption
• Epididymis: A long, coiled tube attached to the testis, divided into head, body, and tail. Storage of sperm, maturation of sperm, and transport of sperm to the vas deferens are the functions of the epididymis.

Hormones of the Testis

Testosterone

• This hormone is the main male sex hormone
• Development of male reproductive organs and development of secondary sexual characteristics (deep voice, facial hair, etc.)
• It stimulates sperm production

Inhibin

• It is secreted by Sertoli cells
• It regulates sperm production by inhibiting FSH (Follicle Stimulating Hormone).

Functions of the Testis

• Production of sperms
• Secretion of male sex hormones
• Development of male secondary sexual characters
• Regulation of reproductive functions

Disorders of the Testis

• Hypogonadism: Reduced hormone production leading to delayed puberty
• Cryptorchidism: A condition where one or both testes fail to descend into the scrotum
• Testicular Tumours: Abnormal growth of cells in the testis

Related Articles:

• Diagram of Testicle
• Male Reproductive System - Structure, Organs, Functions
• Human Body