Fate of a blastopore code#
Fate of a blastopore series#

Fate of a blastopore code#

Edward DeRobertis identified that chordin cDNA could also induce a secondary axis, suggesting that there is redundancy in the genes that code for neural development.

These experiments determined that noggin mRNA can induce normal head and brain development, and that increasing levels of noggin result in larger brain structures and eventually a secondary axis. William Smith extracted mRNA from the dorsal lip of normally developing Xenopus embryos that was then injected into the UV-radiated embryos to see if normal head development could be rescued. Genetic information for neural induction Įxperiments to identify the genetic basis for neural induction were conducted by exposing Xenopus embryos to UV radiation, which causes them to develop with no head. Further investigations were able to identify specific factors such as noggin and chordin as genetic factors in the dorsal lip that are critical for proper neural development.

Fate of a blastopore series#

Future experiments using a series of injections of dorsal lip mRNA into irradiated embryos demonstrated that the dorsal lip contained genetic factors that were sufficient for neural induction. Interest then shifted to identifying the chemical mechanisms underlying the dorsal lip’s organizer function. The dorsal lip of the developing gastrula was thus denoted as the Spemann-Mangold organizer for its role in neural induction and organization of developing neural tissues. Transplantation of the dorsal lip from a Xenopus embryo into the ventral region of a different host embryo demonstrated that an entire secondary axis would form using the host embryo’s own tissue, indicating a clear role of the dorsal lip as a neural inducer and organizer. His research focused on the dorsal lip as a possible organizer of these fate specification changes since it is the first structure to fold inwards during gastrulation. Hans Spemann noted this phenomenon and hypothesized that the tissue rearrangements that occurred during gastrulation must somehow be linked to controlling the fates of developing tissue in the embryo. Early transplantation experiments in developing embryos demonstrated that different layers of the embryo, when isolated and transplanted before gastrulation versus after gastrulation, would develop into distinctly different mature tissues. The dorsal lip refers to the section of tissue located at the site of the first invagination in the developing pregastula and is understood to act as both the neural inducer in the early embryo as well as the overall organizer of the entire body axis. 2 Genetic information for neural induction.