Practice question

Chick oogenesis deposits massive lipoprotein yolk platelets vegetally, displacing metabolically active ooplasm, mitochondria and germinal vesicle to a tiny animal cap. Such extreme polarization where yolk concentrated vegetally and cytoplasm forms thin disc animally defines telolecithal organization. Mesolecithal amphibian eggs have moderate yolk, alecithal mammalian eggs almost none, centrolecithal insect eggs have central yolk surrounded by cytoplasm. Telolecithal architecture dictates meroblastic discoidal cleavage, blastodisc formation, and dependence on epiblast-driven primitive streak gastrulation rather than blastopore invagination, influencing extraembryonic membrane development.