question_answer 56)

  (a) How many spermatozoa are formed from one secondary spermatocyte? (b) Where does the first cleavage division of zygote take place?

Answer:

                  (a) A primary spermatocyte completes the firstmeiotic division (reduction division) leading to formation of two equal, haploid cells called secondary spermatocytes (n=23chromosomes each). The secondary spermatocytes undergo the second meiotic division to produce four equal, haploid spermatids (n)., each spermatids produces permatazoa. (b) The mitotic division called cleavage starts 30 h after fertilization when as to the zygote moves through the isthmus the Fallopian tube (oviduct) towards the uterus and forms blastomeres.