Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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.
How is the transport of substances done across the bryophyte tissues? How is this feature related to the general size of these plants? In bryophytes there are no water-conduct
Enumerate about the Halstead- Reitan battery As in the case of the Halstead- Reitan battery, one could present two theoretical bases for the Luria- Nebraska, one revolving arou
Acute Glomerulonephritis If you review the anatomy of urinary system you will recall that nephron is the working unit of kidney and its number exists in millions. Within t
What is the optimum temperature for catalyses? For any chemical reaction, the reaction rate enhances with temperature, so the higher the temperature, the faster the rate. For a
Q. What are the mechanisms of hemorrhage contention called? The physiological mechanisms of hemorrhage contention one of them is blood clotting are generically named hemostatic
Assess Mobility of Prosthesis All implant-supported prostheses must be stable. To detect mobility, place an explorer or scaler under the embrasures and apply gentle pressure i
Q. Function of Adenosine in brain? Adenosine has four different receptor subtypes (A1, A2A, A2B and A3). Adenosine A2A receptors are concentrated in striatum. Adenosine recepto
Q. Explain Uristix Benedicts test? No sugar/glucose is excreted in the urine in normal individuals. In diabetics, glucose is excreted by the kidneys when the blood sugar levels
How does the inflammation mechanism work? When some tissue injury happens histamine and other vasoactive substances (known as mediators of inflammation) are released, they caus
Risk management option assessment : Identification of available management options Selection of preferred management option , including consideration of an appropriate saf
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd