BIOL 3530 Lecture 3: Chapter 3.1
7 Oct 2016
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A few have been studied extensively, each has advantages and disadvantages. Frog (xenopus laevis): independent development but the known genetics is poor. Chick (gallus gallus): available, surgical manipulation and in vitro culture but poor genetics. Mouse: good genetics (knockouts) but development is in utero. All vertebrate embryos undergo a similar pattern of development: fertilization, cleavage, blastulation, gastrulation (where ectoderm covers embryo, endoderm and mesoderm are inside). The vertebrate body plan consists of the antero-posterior axis (segmented vertebral column and skull) and the dorso-ventral axis (including the ventrally located mouth). All vertebrate embryos pass through the phylotypic stage when the embryos are all similar in appearance. The large eggs of fish, frogs and bird have large yolks that provide nutrients to the developing embryo. Mammalian eggs are small and obtain nutrients from the ovoduct then the placenta. The egg is composed of an animal & a vegetal region, both covered by vitelline membrane.
