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A testicle or testis (pl. testes) is the gonad in all male bilaterians, including humans, and is homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of androgens, primarily testosterone. The release of testosterone is regulated by luteinizing hormone (LH) from the anterior pituitary gland.
The lobules are conical in shape, the base being directed toward the circumference of the organ, the apex toward the mediastinum testis. Each lobule is contained in one of the intervals between the fibrous septa which extend between the mediastinum testis and the tunica albuginea , and consists of from one to three, or more, minute convoluted ...
There are two types: convoluted and straight, convoluted toward the lateral side, and straight as the tubule comes medially to form ducts that will exit the testis. The seminiferous tubules are formed from the testis cords that develop from the primitive gonadal cords, formed from the gonadal ridge.
It carries with it the ductus deference, which are testicular vessels and nerves, a portion of the abdominal muscle, and lymph vessels. All of the structures remain attached to the testis and form what is known as the spermatic cord. By the time the testis is in the scrotal sac, the gubernaculum is no more than a remnant of scar like tissue. [10]
The tunica albuginea is a dense, [1] [2] blue-white [3] layer of fibrous tissue surrounding the testis. [1] [4] It is the middle of three envelopes forming the capsule of the testis; it is deep to the visceral layer of tunica vaginalis, and superficial to the tunica vasculosa testis (vascular layer of testis).
Sertoli cells are a type of sustentacular "nurse" cell found in human testes which contribute to the process of spermatogenesis (the production of sperm) as a structural component of the seminiferous tubules. They are activated by follicle-stimulating hormone (FSH) secreted by the adenohypophysis and express FSH receptor on their membranes.
The mediastinum testis is a thick yet incomplete septum at the posterior part of the testis formed by the tunica albuginea of testis projecting into the testis at its posterior aspect where the testis is not lined by the serous membrane to allow for the attachment of the epididymis.
Normally the testes begin its descent through the inguinal canal to the scrotum at 36 weeks’ of gestation and completed at birth. Failure in the course of testes descent will result in undescended testes (Cryptorchidism). Undescended testis is found in 4% of full-term infants but only 0.8% of males at the age of 1 year have true cryptorchidism.