Involution - internalization of mesoderm, Biology

Involution - Internalization of Mesoderm

As by now mentioned, in the frog Xenopus (and probably in other amphibian species as well) the cells of presumptive mesoderm are in the deeper layers of the dorsal and lateral marginal zones beneath the superficial layer that is presumptive endodermal. The complete mesoderm is internalized through involution over the blastoporal lips. , at the same time with the involution of endoderm of the superficial layer the chorda- mesoderm situated in the dorsal marginal zone (gray crescent) involutes over the dorsal lip, the presumptive somitic mesoderm over the lateral lips and the presumptive lateral plate mesoderm over the ventral lip. As the dorsal lip is formed first and venual lip last the involution first starts in the region of the dorsal marginal zone followed successively in the lateral and ventral regions of the lateral marginal zone. The mesodermal cells of deep layers first interdigitate creating a single thick layer in which cell division as well occurs. The layer together with the overlying superficial endodermal layer converges in the direction of the blastoporal lips, where the edges of the two layers break up into separate cells, which now, involute individually and move into the interior.

The involuting mesodermal cells retain their deep position throughout and after involution. The cells of the presumptive chorda-mesoderm involute over the dorsal lip in successive waves and one time inside they migrate actively as streams anteriorly towards the animal pole. The path of migration is beside the mid-dorsal line between the non-involuted layer of the surface of animal zone above and the layer of involuted endodermal cells below. The cells of first such types of streams reach the future head region where they make the head mesoderm. They are followed by other successive streams of involuted cell that make the notochord above the archenteron. Internalization of the presumptive somitic and lateral plate mesoderm of the lateral marginal zone occurs in the same way. After involution over the lateral and ventral blastoporal lips correspondingly, these cells move in an anterior direction to form a loosely organized layer called mesodermal mantle on either side of archenteron.

Posted Date: 1/25/2013 5:13:57 AM | Location : United States

Related Discussions:- Involution - internalization of mesoderm, Assignment Help, Ask Question on Involution - internalization of mesoderm, Get Answer, Expert's Help, Involution - internalization of mesoderm Discussions

Write discussion on Involution - internalization of mesoderm
Your posts are moderated
Related Questions
Explain the requirements of Special Stains? Special stains are required to make spores clearly visible. Different techniques like negative staining, dorner staining method, sch

CHF complicating IE is primarily the result of valve destruction or distortion or rupture of chordae tendinae. Intracardiac fistulas, myocarditis, or coronary artery embolization m

Define Metabolic Activity and Cell Constituents? Metabolic activity like amount of acid produced or CO 2 produced is directly proportional to the number of bacteria present, s

What is the genetic condition in which the heterozygous individual has different phenotype from the homozygous individual? This condition is called lack of dominance and it can

Nutrient Cycles All ecosystems have certain common basic features of structure and function. They all have living and non-living components through which there is a flow of en

Explain about the Microbiological Study of Water? Water is the basic need of life. River, streams and underground water is the prime source for water. However, disposal of indu

PITUITARY GLAND (HYPOPHYSIS CEREBRI) - It develops from ectoderm of the embryo. The pituitary gland is located just below the hypothalamus. The pituitary gland is situate

Transposable elements are able to move around the genome by precise or imprecise excision events. What is meant by imprecise excision? A. Imprecise excision refers to a transpo

How are the organelles of a single cell like the organs of a multicellular organism? Name two features of eukaryotic cells that prokaryotic cells lack.

Define Nitrogen Estimation - Kjeldahl's Method? Nitrogen in the protein is estimated by a method referred to as Kjeldahl's method. Although over a period of time many other met