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The epididymis is present in male reptiles, birds, mammals, and cartilaginous fish. [1] The caput epididymidis is fused to the testis in eutherian mammals, but not in marsupials. [13] In reptiles, there is an additional canal between the testis and the head of the epididymis and which receives the various efferent ducts.
The mechanism by which sperm storage in the epididymis is enhanced at lower extra-abdominal temperatures has been shown to be a consequence of the biophysics of oxygen availability and sperm oxidative respiration. [12] The cauda epididymis, where sperm are stored, can be up to 7 °C below abdominal temperatures.
As a result of the epididymis being attached to the testis, and the cauda epididymis extending below the lower extremity of the testis (Figure 1C), it was proposed that the epididymis was the prime mover in the evolution of testicular decent, whereby the cauda epididymis preceded the testis into a scrotal location. [1]
The function of the blood–testis barrier may be to prevent an auto-immune reaction. [13] Mature sperm (and their antigens) emerge significantly after immune tolerance is set in infancy. [13] Since sperm are antigenically different from self-tissue, a male animal can react immunologically to his own sperm. The male can make antibodies against ...
The epididymis is a long whitish mass of tightly coiled tube. The sperm that are produced in the seminiferous tubules flow into the epididymis. During passage via the epididymis, the sperm undergo maturation and are concentrated by the action of ion channels located on the apical membrane of the epididymis. [2]
The seminiferous tubules of the testes are the starting point for the process, where spermatogonial stem cells adjacent to the inner tubule wall divide in a centripetal direction—beginning at the walls and proceeding into the innermost part, or lumen—to produce immature sperm. [2] Maturation occurs in the epididymis.
If the fetus has testes and the testes produce testosterone, and if the cells of the genitals respond to the testosterone, the outer urogenital folds swell and fuse in the midline to produce the scrotum; the protuberance grows larger and straighter to form the penis; the inner urogenital swellings grow, wrap around the penis, and fuse in the ...
In a male embryo, the testicular cords will induce the development of the Wolffian duct into the vas deferens, epididymis and the seminal vesicle and cause the repression and regression of the Mullerian duct. [4] The other male sex organs (ex. the prostate) as well as external genitalia are also formed under the influence of testosterone. [4]