Sexual reproduction in mammals Flashcards
Germ cell
diploid cells which give rise to gametes through meiosis
Polar body
a small haploid cell that is formed at the same time as an egg cell during oogenesis, but generally does not have ability to be fertilised
Germinal epithelium
a single layer of cells that undergoes regular mitosis, producing other cells
Sertoli cells
supply metabolises and nutritive factors to spermatocytes, spermatids and developing sperm
Graafian follicle
each follicle starts as a layer of cells around the oocyte but eventually develops into a fluid filled sac
Corpus luteum
the empty graafian follicle becomes filled with hormone secreting cells, forming a yellow body
Gametogenesis
process of gamete production
- the female and male gametes are produced in organs called gonads
what is the female gonads called ?
ovaries - produces ova
what is the male gonads called ?
testes - produces spermatozoa
Spermatogenesis
- germ cells divide several times by mitosis to form spermatogonia
- spermatogonia grow without further division to form primary spermatocytes
- primary spermatocytes undergo the first meiotic division to form secondary spermatocytes
- secondary spermatocytes undergo the second meiotic division to form spermatids
- spermatids differentiate and grow to form mature spermatozoa
Oogenesis
- germ cells divide several times by mitosis to form oogonia
- only one oogonium continues to grow to form a primary oocyte
- the first meiotic division forms one secondary oocyte and one polar body
- the second meiotic division of the secondary oocyte forms one haploid ootid and one polar body - than forms two more polar bodies
- degenerate and die as the ootid develops
what does the ovum contain ?
- zona pellucida
- haploid nucleus
- cortical granules
- follicle cells
Zona pellucida
protective coating that the sperm have to penetrate in order for fertilisation to occur
main purpose: to prevent polyspermy
Haploid nucleus - ovum
full set of chromosomes is restored at fertilisation
Cortical granules
release substances which cause the zona pellucida to harden, forming a tough fertilisation membrane