BIOL 3530 Lecture 5: Chapter 3.3
7 Oct 2016
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All vertebrate embryos are similar at the phylotypic stage. Somites, notochord and neural tube show a/p organization. Patterning turns mesoderm into repeated structures of skeleton and trunk muscles. Dorsal mesoderm during gastrulation is internalized to eventually become the notochord and the somites. The notochord is transient & becomes part of spinal column. With neuralation, ectoderm overlaying the notochord forms the neural tube to give rise to brain & spinal cord. Somites, mesoderm in blocks flanking notochord, become the : vertebrae and ribs, muscles of the trunk and limbs and, contribute to the dermis. The role of the organizer and neural induction. Spemann organizer (dorsal blastopore lip) grafted to the ventral side of the marginal zone results in a twinned embryo. The second embryo can have head, trunk and, sometimes, a tail) but will be joined to primary embryo along the axis. Late gastrula induces only tail. and as it progresses the.
