REPRODUCTION IN MAMMALS (Past Year Essay)

Master reproduction: compare mammal gametes & double fertilization!

PSPM I 2012 between the spermatogenesis and oogenesis ( 10m)Complete the paragraph with the correct answers. Similarities-Hormone such as LH,FSHand GnRHare involved in both spermatogenesis and oogenesis-Spermatogenesis and oogenesisinvolved meiosis to produced haploid gametesDifferences-Spermatogenesis take place in the seminiferous tubulesof the testesbut oogenesis takes place in ovaries-Spermatogonia divide by mitosis , some differentiate and become primary spermatocytes, which undergo meiosis.-The first meiotic division produces two secondary spermatocytes.-In the second meiotic division, each secondary spermatocytes produces two spermatids .-Each spermatid differentiates to form mature sperm-while Oogonia differentiate into primary oocytes in oogenesis-A primary oocyte and the granulosa cells surrounding it make up follicle.- As the follicle matures, the primary oocyte undergoes the first meiotic division, giving rise to a secondary oocyteand a polar body .-The secondary oocyte begins the second meioticdivision but the process stop at metaphase .- If fertilizationoccurs, meiosis IIwill be completed producing an ovumand the second polar body . PSPM 1 2012 the process of double fertilization beginning with pollen germination (8m) -Pollen tube emerges from the pollen (through a pore in the exine) --Pierces the style-It grows until it reaches the micropyle-The generative nucleus divides by mitosis-Produces two nuclei sperm cells/ 2 male gamete-The tube nucleus degenerates-One male gamete fuses with an egg cell- Forms diploid zygote- Another male gamete fuses with two polar nuclei- Forms triploid 3n endosperm