Temperature dependent sex determination ppt to pdf in Kingston upon Hull

Spermatocytogenesis is the male form of gametocytogenesis and results in the formation of spermatocytes possessing half the normal complement of genetic material. This anatomic arrangement prolongs the time of contact and the thermal exchange between the testicular arterial and venous blood streams and may, in part, explain the temperature gradient between aortic and testicular arterial blood reported in dogs5 and rams.

If the pituitary gland is removed, spermatogenesis can still be initiated by follicle stimulating hormone FSH and testosterone. Spermatozoa are the mature male gametes in many sexually reproducing organisms.

While the sex of most snakes and most lizards is determined by sex chromosomes at the time of fertilization, the sex of most turtles and all species of crocodilians is determined by the environment after fertilization. Results indicated that in the second season, during which most lizards became reproductive, males raised at intermediate temperatures had the greatest reproductive success of all the males, while females at extreme temperatures had more offspring than those raised at intermediate temperatures.

Other species show disproportionately high female production at both high and low temperatures, with intermediate temperatures causing mostly male development. Ohno, Susumu. Individuals with low levels of aromatase during the thermosensitive period will develop male characteristics.

Temperature dependent sex determination ppt to pdf in Kingston upon Hull

Seminiferous epithelium is sensitive to elevated temperature in humans and some other species, and will be adversely affected by temperatures as high as normal body temperature. Male reproductive system. They are capable of producing the hormones estradiol and inhibin.

In spermatocytogenesis, a diploid spermatogoniumwhich resides in the basal compartment of the seminiferous tubules, divides mitotically, producing two diploid intermediate cells called primary spermatocytes. Endocrinology 6th ed. Testosterone is required in large local concentrations to maintain the process, which is achieved via the binding of testosterone by androgen binding protein present in the seminiferous tubules.

The resulting spermatozoa are now mature but lack motility.

One important mechanism is a thermal exchange between testicular arterial and venous blood streams. Categories : Animal developmental biology Animal physiology Mammal male reproductive system. Maturation then takes place under the influence of testosterone, which removes the remaining unnecessary cytoplasm and organelles.

Spermatid DNA also undergoes packaging, becoming highly condensed. The entire process of spermatogenesis can be broken up into several distinct stages, each corresponding to a particular type of cell in humans.

Temperature dependent sex determination ppt to pdf in Kingston upon Hull

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