Gametogenesis Flashcards
Describe in single terms spermatogenesis.
Germinal epithelial - mitosis - spermatogonia - mitosis - primary spermatocytes - meiosis 1 - secondary spermatocytes - meiosis 2 - spermatids - maturation - spermatozoa
What cells are diploid and haploid in spermatogenesis?
Germinal epithelial - diploid Spermatogonia- diploid Primary spermatocytes - diploid Secondary spermatocytes - haploid Spermatids- haploid Spermatozoa - haploid
Briefly describe the structure of a sperm cell.
Head containing the nucleus, surrounded by the acrosome which contains enzymes for fertilisation, microtubules extend from the centriole to the axial filament, surrounded by mitochondria for ATP, flagellum used to swim (but not until motile).
Describe in single terms oogenesis.
Germinal epithelium - mitosis - oogonia + follicle cells - mitosis - primary oocytes and polar body - start meiosis 1 but stop at prophase 1 - finish meiosis 1 - secondary oocytes and polar body - start meiosis 2 but stop at metaphase 2 - complete meiosis 2 - ovum - fertilisation - zygote
What stages occur before birth and during puberty and fertilisation?
Germinal epithelium - oogonia - primary oocytes and polar body - start meiosis 1 but stop at prophase 1 = BEFORE BIRTH
Primary oocytes - finish meiosis 1 - secondary oocytes and polar body - start meiosis 2 but stop at metaphase 2 = PUBERTY EVERY MONTH
Secondary oocytes finish meiosis 2 - ovum = FERTILISATION
What cells are diploid and haploid in oogenesis?
Germinal epithelium = diploid Oogonia = diploid Primary oocytes = diploid Secondary oocytes = haploid Ovum = haploid Zygote = diploid Polar bodies = haploid
What are polar bodies and why are they necessary?
In oogenesis meiosis results in uneven splitting of the cytoplasm. The oocytes must have as much cytoplasm as possible to provide nourishment for the embryo until it reaches the endometrium. This is achieved by making polar bodies which are haploid and very small so can’t be fertilised.
