With the discovery of much earlier events that established the embryonic axes in the 1980s, insights began to be gained about where and how the blastopore and the organizer will form. For more than fifty years following Spemann, there was confusion about what property or product of the dorsal lip tissue was responsible for in its role as an organizer. The more dorsal part of the organizer is characterized by expression of TF-Xnot, and can induce trunk. Spemann concluded that the mesoderm of the dorsal lip region is important. Convergent extension closes the blastopore at the yolk plug and elongates the embryo along the anterior. The blastopore continues to develop from the early 'frown' until it can be observed as a complete circular ring of involuting cells. Eventually the embryo developed two heads. Early on, the dorsal lip of the blastopore forms due to the contraction of bottle cells (see below). Later, neural ridges formed not only near the normal blastopore, but also near a secondary blastopore. The blastopore lip is the group of cells in the developing embryo that induces the beginning of gastrulation and the development of the germ layers. Since then, it has been known as Spemann’s organizer. What experimental evidence (by Spemann and Mangold) demonstrated the organizing ability of the dorsal lip of the blastopore When the Spemann organizer was graved onto the ventral side of the marginal zone, a twinned embryo was the result. The transplanted mesoderm formed a blastopore and moved inside the embryo. It was Hans Spemann ((1869-1941) who identified the dorsal lip as the organizer, together with his graduate student Hilde Mangold (1898-1924), for which he received the Nobel Prize for Physiology or Medicine in 1935. Frequently mentioned examples of an organizer are the dorsal lip of the blastopore and Hensen’s node. Any part of an embryo capable of inducing another part to differentiate.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |