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

Can you explain secondary metabolites, Q. Can you explain Secondary Metabol...

Q. Can you explain Secondary Metabolites? Secondary metabolites or secondary plant products are those macromolecules that lack nitrogen and arc of restricted occurrence and the

Egg type, why their is different amount of yolk is present in eggs.

why their is different amount of yolk is present in eggs.

Define iodothyronine deiodinases - functions of selenium, Define Iodothyron...

Define Iodothyronine Deiodinases - functions of selenium in humans? Another group of selenoproteins are the iodothyronine deiodinases essential for the conversion of thyroxine

What is eukaryotic cells , What is Eukaryotic Cells ? Eukaryotic Cel...

What is Eukaryotic Cells ? Eukaryotic Cells :  Most cells of higher organisms, and many unicells, contain a nucleus. Organisms whose cells contain a nucleus are called euka

What is glycogen metabolism, Glycogen is a multibranched polysaccharide whi...

Glycogen is a multibranched polysaccharide which serves as a part of energy storage in fungi and animals. In humans the glycogen is recognized and stored primarily in the cells of

Describe microtubular cytoskeleton in protozoans, Protozoans have endoskele...

Protozoans have endoskeletons formed from microtubular cytoskeleton of the exoskeletons or cytoplasm secreted as shells or tests. Some of these single-cell organisms are capable of

Explain the term viruses, Normal 0 false false false EN...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

Types of parthenocarpy, Types of Parthenocarpy Three types of Partheno...

Types of Parthenocarpy Three types of Parthenocarpy are generally recognized: Genetical Environmental, Chemically-induced. Genetical Parthe

Radiation pollution, Radiation Pollution It is unfortunate that harmfu...

Radiation Pollution It is unfortunate that harmful radiations cause severe pollution but they cannot be seen or observed by eyes and are difficult to judge, unless present in

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