Problem of polarity, Biology

Assignment Help:

Problem of Polarity

The control of polarity in regenerating coelentrates like hydra has received much attention for many years. You are already aware that while a hydra is cut in half, the half with the basal disc will form a hew hypostome and the half consisting of the hypostome will generate a new basal disc. Furthermore, if a hydra is cut into various segments perpendicular to the body axis, then each middle segment will regenerate both of the a basal disc and a hypostome. So every region of the hydra can give rise to a new organism.

Yet hypostomes, as well foot does not make anywhere or at all levels along the longitudinal axis of the animal; they form just only at the distal end. This indicates that a series of gradients arise from the two poles in Hydra that is rigidly polarized along the distal proximal axis. Grafting experiments have given further evidence for the existence of gradients in the hydra. When the hypostome tissue was added to the middle region of other hydra it formed a new bud with hypostome extending outward. When the basal disc cells were likewise grafted the new bud extended to form a new pedal disc and foot. In addition if grafts of both basal disc and hypostome cells were grafted together to the gastric region no supernumerary parts made. This observation suggests which signals from opposite ends of the hydra tend to counteract each other, causing the hydra to lose its polarity. Other experiments have as well shown which normal regeneration of the hypostome can be inhibited when an intact hypostome is grafted into the body of the hydra.


Related Discussions:- Problem of polarity

Name the endocytosis, Name the endocytosis?   A.  During endocytosis of...

Name the endocytosis?   A.  During endocytosis of GLUT4 transporters in fat cells, there is removal of GLUT4 transporters from plasma membranes.   B.  During endocytosis of

What are pentoses, Pentoses are carbohydrates form of five carbons. Deoxyri...

Pentoses are carbohydrates form of five carbons. Deoxyribose is the pentose that constitutes DNA nucleotides and ribose is the pentose that is part of RNA nucleotides

What is a distilling flask and how is it used, What is a distilling flask a...

What is a distilling flask and how is it used? A distilling flask is a round bottom flask that often has two openings, and some of them have a long neck.

Explain matching energy intake to energy expenditure, Explain Matching ener...

Explain Matching energy intake to energy expenditure? To be in energy balance, an athlete needs to consume about the same number of calories that he or she expends on a daily

What are organogenesis and histogenesis, Q. What are organogenesis and hist...

Q. What are organogenesis and histogenesis? Histogenesis is the procedure of tissue formation in the embryonic development. Organogenesis is the procedure of organ formation. B

Peste des petits ruminants (ppr), Peste des petits ruminants (PPR) is an a...

Peste des petits ruminants (PPR) is an acute, highly contagious viral disease of goats and sheep caused by peste des petits ruminants (PPR) virus which belongs to the genus Morbil

Explain the chloride permeability, An impermeable membrane separates one li...

An impermeable membrane separates one liter of a 1M KCl solution in the left compartment from one liter of 1M NaCl solution in the right compartment.  At 2 AM today the membrane be

Explain nucleosides, Nucleosides : compounds formed from a nitrogenousba...

Nucleosides : compounds formed from a nitrogenousbase and  a penstose sugar.

State the purpose of a neuropsychological screening, State the purpose of a...

State the purpose of a neuropsychological screening The purpose of a neuropsychological screening examination is to determine if there is reasonable evidence, beyond initial cl

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd