Gastrulation in birds and frogs differs considerably. The main feature that both share is a. three germ layers are established. This is an example of the cells being a. totipotent. The mammalian egg cell is about twice as large as the sperm. The zygote's mitochondria come from the sperm.
Spermatogenesis produces four haploid spermatids from the precursor cell.
Oogenesis produces a. four haploid egg cells. All rights reserved.