Testis: In humans each testis weighs about 25 grams (0.875 ounce) and is 4–5 cm (1.6–2.0 inches) long and 2–3 cm (0.8–1.2 inches) in diameter. Each is covered by a fibrous capsule called the tunica albuginea and is divided by partitions of fibrous tissue from the tunica albuginea into 200 to 400 wedge-shaped sections, or lobes. Within each lobe are 3 to 10 coiled tubules, called seminiferous tubules, which produce the sperm cells. The partitions between the lobes and the seminiferous tubules both converge in one area near the anal side of each testis to form what is called the mediastinum testis.
Functions of Testis
- It is the male reproductive gland in all animals, including humans. It is similar to the ovary in females.
- It is a mixed gland, which means it has both exocrine and endocrine functions.
- The endocrine function of the testis is the secretion of testosterone which occurs from the Leydig cells. It is the predominant male steroid hormone.
- The exocrine function of the testis is the release of sperm. The sperms are the male gametes produced inside the male reproductive gland.
- It also acts as the storage structure of the sperm and the testis is present inside the scrotum. The temperature inside the scrotum is lower than the actual body temperature, which keeps the sperms stored in the testis viable.
Histology of Testis
- It is an oval egg-like structure found in men.
- They are two in number.
- It is a structure consisting of three layers known as the tunica vaginalis, tunica vasculosa, and tunica albuginea.
- Each testis has many compartments described as testicular lobules.
- In each lobule, there are 1-3 coiled seminiferous tubules.
- Sperm is produced by these tubules.
- The stratified epithelia of the seminiferous tubules are constituted of Sertoli cells and male germ cells.
- These cells divide to become spermatozoa.
- The Leydig cells are found between the testosterone-secreting tubules.
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By Team Learning Mantras