BIOL 102 Lecture Notes - Lecture 24: Teiidae, Spermatocyte, Spermatogonium
Document Summary
May also engage in sexual reproduction or sexual behavior. Part of the mechanism that determines sex (ex: honey bees: males develop from unfertilized eggs and are haploid, females develop from fertilized eggs and are diploid. Male and female germ cells proliferate by mitosis and produce diploid spermatogonia and oogonia that mature into primary spermatocytes and oocytes before entering meiosis. Male germ cells mitosis in the embryo spermatogonia. Primary spermatocytes first meiotic division secondary spermatocytes. Second meiotic division 4 haploid spermatids for each primary spermatocyte. Mammals: progeny of primary spermatocytes remain connected by cytoplasmic bridges after each division (due to asymmetry of male sex chromosomes) Half spermatocytes receive an x chromosome and the other half a y chromosome. Genes on x chromosome are essential for spermatocyte development. Cytoplasmic contact = all four spermatocytes can share the gene products of the x chromosomes. Spermatid spermiogenesis compact, streamlines and grows a flagellum to become motile. Oogonia mitosis primary oocytes (immediately enter prophase) meiosis.
