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

How is the genetic determination of sex established in human, How is the ge...

How is the genetic determination of sex established in humans? In the diploid genome of human beings there are 46 chromosomes, 44 of them are autosomes and two are sex chromoso

Self - medication, SELF - MEDICATION - Self medication refers to the us...

SELF - MEDICATION - Self medication refers to the use of medicines without consulting a physician. Self medication may be harmful, rather dangerous. It must be avoided. (i)

Do squids and octopus have exoskeleton, Q. Do squids and octopus have exosk...

Q. Do squids and octopus have exoskeleton? Squids and Octopus generally do not produce external shell (some squid species can have an internal shell). One cephalopod group the

Effect of alcohol on human body, EFFECT OF ALCOHOL - 1 .       EFFECT...

EFFECT OF ALCOHOL - 1 .       EFFECT ON NERVOUS SYSTEM - Alcohol has an anesthetic effect on nervous system. It affects orientation, alertness, coordination, judgement

Calculate ideal weight for a diabetic patient, Q. Calculate ideal weight fo...

Q. Calculate ideal weight for a diabetic patient? We now know that diabetes is the outcome of many genetic and environmental factors. The former is not in our control but the l

Effects of long term malnutrition on adults, Effects of long term malnutrit...

Effects of long term malnutrition on adults In adults, once the stored carbohydrates and fats are used up, the body starts using proteins to generate energy. These protei

Mollusca, commercially important bivalve species

commercially important bivalve species

Describe the basic mechanisms in plaque formation, Q. Describe the Basic Me...

Q. Describe the Basic Mechanisms in Plaque Formation? In experimental models and human disease, the first morphologic phenomenon observed in plaque formation is adhesion of mon

What are the two reproductive novelties of beings, Compared to amphibians w...

Compared to amphibians what are the two reproductive novelties of beings of the class Reptilia for the survival in dry environments? Compared to amphibians the two major reprod

What is cerebrum, What is Cerebrum Cerebrum is divided into right and l...

What is Cerebrum Cerebrum is divided into right and left parts known as cerebral hemisphere. It is the largest part of the brain. The functions of the cerebrum:  It recei

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