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spermatogenesis - okt3
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09-03-2007, 07:39 PM
In spermatogenesis, at which stage do the sex chromosomes
segregate? (A) Meiosis II, primary spermatocyte (B) Meiosis I, primary spermatocyte © Meiosis II, secondary spermatocyte (D) Meiosis I, secondary spermatocyte (E) Meiosis II, spermatid
09-03-2007, 07:47 PM
what means chromosomes segregate? with or without centromere seperation? not sure, what about B?
09-03-2007, 07:51 PM
The answer is B.
Spermatogenesis occurs in the seminiferous tubules of the testes of the male from the time of sexual maturity onward throughout adulthood. Spermatogonia are found at the periphery of the tubules. These spermatogonia are of several cell types, ranging from a self-renewing stem cell to a more specialized cell that is committed to sperm formation. The last stage of the developmental sequence is the primary spermatocyte. This cell undergoes meiosis I: the primary spermatocyte divides to form two secondary spermatocytes, each with 23 chromosomes. These cells rapidly undergo meiosis II, forming two spermatids. The spermatids mature without further division into spermatozoa and are released into the lumen of the tubule. The total time involved for all stages of spermatogenesis from the beginning of meiosis I to the formation of a mature sperm is approximately 64 days, and as many as 200 million sperm are produced per ejaculate. |
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