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In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm cell , ( spermatozoon ). [1]
Throughout the animal kingdom, an incredible variety of embryonic types exist, but most patterns of embryogenesis are variations on five themes: 1. Immediately following fertilization, cleavage occurs.
EXPERIMENTAL EMBRYOLOGY: It involves all those studies that attempt to understand the various fundamental mechanism in the development of different animals, like fertilization, Cleavage, Gastrulation, Embryonic induction, determination and differentiation. 4.
Embryogenesis: — formation of body structures & organs (organogenesis) — requires cell division (proliferation) and cell differentiation (specialization) — produces the great variety of cell types and extracellular products found in the body. Cell specialization:
Feb 6, 2018 · Embryogenesis start from the time of fertilization of female germ cell or ovum by a sperm. The zygote formed is surrounded by a strong membrane of glycoproteins called the zona pellucida which...
Jan 1, 2016 · Fertilization generally takes place in the oviduct and the zygote is implanted into the uterus. In the preimplantation embryo several maternal genes are expressed. After fertilization the oocyte-stored mRNAs are degraded in about 90% by the two-cell stage of mice.
As an animal embryo develops, its cells divide, grow, and migrate in specific patterns to make a more and more elaborate body (plant cells perform differential expansion instead of migration). To function correctly, that body needs well-defined axes (such as head vs. tail aka anterior vs. posterior).
