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As the blastopore deepens, a new embryonic cavity develops, the primitive gut, or the archenteron. It grows in length towards the future front part of the embryo. It can be seen from outside the embryo that the dorsal lip curves itself and grows, creating the side lips of the blastopore. During this time, the paraxial mesoderm enters the embryo.
A typical frog embryo, incubated at 18 °C, is an early stage neurula by 50 hours post-fertilization and a late stage neurula by 67 hours. [3] The mouse embryo begins neurulation on day 7.5 of gestation and remains in the neurula stage until day 9.
Gastrulation then continues along the ventroposterior blastopore lip and posterior streak region, from where cells contribute to ventral and posterior mesoderm. Adding to this, Brachyury and caudal homologues are expressed circumferentially around the blastopore lips in the frog, and along the primitive streak in chick and mouse. This would ...
Gosner stage 31 tadpole of Nidirana leishanensis. (A) Dorsal view. (B) Lateral view. (C) Ventral view. (D) Mouth structure. [1]Gosner stage is a generalized system of describing stages of embryonal and larval development in anurans (frogs and toads).
Frog (Xenopus), as well as other amphibian, gastrulation serves as an excellent example of the role of convergent extension in embryogenesis. During gastrulation in frogs, the driving force of convergent extension is the morphogenic activity of the presumptive dorsal mesodermal cells; this activity is driven by the mesenchymal cells that lie ...
Upon fertilization, this membrane splits off from the surface of the egg and the space between the vitelline membrane and the embryo is filled with perivitelline fluid. This fluid surrounds the embryo and yolk plug. The yolk Plug nourishes the embryo and indicates that the embryo is near the end of gastrulation.
The Spemann-Mangold organizer is a group of cells that are responsible for the induction of the neural tissues during development in amphibian embryos.First described in 1924 by Hans Spemann and Hilde Mangold, the introduction of the organizer provided evidence that the fate of cells can be influenced by factors from other cell populations. [1]
The primitive streak is a structure that forms in the early embryo in amniotes. [1] In amphibians, the equivalent structure is the blastopore. [2] During early embryonic development, the embryonic disc becomes oval shaped, and then pear-shaped with the broad end towards the anterior, and the narrower region projected to the posterior.