The male gonads, testes or testicles, begin their development high in the abdominal cavity , near the kidneys. During the last two months before birth, or shortly after birth, they descend through the inguinal canal into the scrotum , a pouch that extends below the abdomen , posterior to the penis. This lower temperature is necessary for the production of viable sperm.
The scrotum consists of skin and subcutaneous tissue. A vertical septum , or partition, of subcutaneous tissue in the center divides it into two parts, each containing one testis. Smooth muscle fibers, called the dartos muscle , in the subcutaneous tissue contract to give the scrotum its wrinkled appearance. When these fibers are relaxed, the scrotum is smooth. Another muscle, the cremaster muscle , consists of skeletal muscle fibers and controls the position of the scrotum and testes.
When it is cold or a man is sexually aroused, this muscle contracts to pull the testes closer to the body for warmth. Each testis is an oval structure about 5 cm long and 3 cm in diameter. A tough, white fibrous connective tissue capsule , the tunica albuginea , surrounds each testis and extends inward to form septa that partition the organ into lobules.
There are about lobules in each testis. Each lobule contains 1 to 4 highly coiled seminiferous tubules that converge to form a single straight tubule, which leads into the rete testis.
Short efferent ducts exit the testes. Interstitial cells cells of Leydig , which produce male sex hormones, are located between the seminiferous tubules within a lobule. Sperm are produced by spermatogenesis within the seminiferous tubules.
What is the use of testis? The testicles are the male gonads — the primary male reproductive organs. They have two, very important functions that are very important to the male reproductive system: they produce gametes, or sperm, and they secrete hormones, primarily testosterone. Where are Sertoli cells located? The supporting cells Sertoli are located within the seminiferous tubules. Their task is the creation of a hemato-testicular barrier and the nourishment of the spermatozoa.
What is the rete testis? It is the counterpart of the rete ovarii in females. What is the function of epididymis? It transports and stores sperm cells that are produced in the testes. It also is the job of the epididymis to bring the sperm to maturity, since the sperm that emerge from the testes are immature and incapable of fertilization.
During sexual arousal, contractions force the sperm into the vas deferens. What is a testicle made out of? The testes are covered by a tough membranous shell called the tunica albuginea.
Within the testes are very fine coiled tubes called seminiferous tubules. The tubules are lined with a layer of cells germ cells that develop from puberty through old age into sperm cells also known as spermatozoa or male gametes. There are about of these tubes in each testis, each is the length of an arm and the width of a few hairs; the whole collection of tubules is longer than a football pitch! Once the sperm are produced in the seminiferous tubules they pass into the epididymis, a long coiled tube in which sperm mature as they are conveyed along it.
They are then ready to be released at ejaculation via the vas deferens. The main hormone secreted by the testes is testosterone, an androgenic hormone. Testosterone is secreted by cells that lie between the seminiferous tubules, known as the Leydig cells. Testosterone is important in the first stages of developing the male reproductive organs in a foetus. It also causes the development of male characteristics such as growth of facial hair, deepening of the voice and the growth spurt that takes place during puberty.
From puberty onwards, testosterone provides the main stimulus for sperm production. Many things can wrong with the testes; they can be grouped into physical injury and diseases or conditions that affect the function of the testes:.
Other factors that can affect the function of the testes are radiation and chemotherapy used in the treatment of cancer , certain drugs, and disorders of the pituitary gland that stop signals from the hormone endocrine system that trigger production of testosterone from the testes. About Contact Events News.
0コメント