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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.
Diagram of stages of embryo development to a larval and adult stage. In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm cell (spermatozoon). [1]
Before gastrulation, the embryo is a continuous epithelial sheet of cells; by the end of gastrulation, the embryo has begun differentiation to establish distinct cell lineages, set up the basic axes of the body (e.g. dorsal–ventral, anterior–posterior), and internalized one or more cell types including the prospective gut. [2]
Embryo: 1 to 20 (about) Intracapsular. Development through cleavage, gastrulation, and appearance of neural tube and eventually gills and tail. Hatchling: 21 (about) to 24: Transition from relatively immobile embryo to an active, feeding tadpole. Specimens at these stages may sometimes be referred to as "larvae". Tadpole: 25 to 41
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 ...
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 ...
In the aquatic frog Xenopus egg, the germ cell determinants are found in the most vegetal blastomeres. These presumptive PGCs are brought to the endoderm of the blastocoel by gastrulation. They are determined as germ cells when gastrulation is completed. Migration from the hindgut along the gut and across the dorsal mesentery then takes place ...