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

Respiratry system, prepare a power point presantation of respiratry system

prepare a power point presantation of respiratry system

Hand washing in sterilization process, Q. Hand Washing in sterilization pro...

Q. Hand Washing in sterilization process? Hand washing is considered the single most important measure to reduce the risk of transmitting organisms to patients and HCWs (health

Define viscosity - property of agar, Viscosity The viscosity at tempera...

Viscosity The viscosity at temperatures above its gelation point is relatively constant  at pH values of 4.5  to 9.0 and is not greatly affected by age or ionic strength within

Pattern of growth, P A TTERN OF GROWTH - 1 .       ISOMETRIC - ...

P A TTERN OF GROWTH - 1 .       ISOMETRIC - In it an organ grows at the same rate as the rest of body. External form of body is not changed. eg. fish, locust. 2 .

Uricotelic excretion essential for avian and reptile embryos, Why is the ur...

Why is the uricotelic excretion essential for avian and reptile embryos? In reptiles and birds the excretory system is uricotelic as uric acid is insoluble, less toxic and sui

Explain the development of cancer, Explain the Development of Cancer? A...

Explain the Development of Cancer? Are you interested in knowing how cancer develops? Well here it is. The cancer development is a process involving initiation, promotion and p

Explain the feeding 6-12 months infant, Explain the Feeding 6-12 Months Inf...

Explain the Feeding 6-12 Months Infant? As the infant grows older, mother's milk alone is not sufficient to meet his increasing needs. This could be seen in few infants between

What is the tertiary structure of a protein, The tertiary protein structure...

The tertiary protein structure is a spatial conformation additional to the secondary structure in which the alpha helix or the beta-sheet folds up itself. The forces that stay the

Organogenesis - plant tissue and organ culture, Organogenesis - Plant Tissu...

Organogenesis - Plant Tissue and Organ Culture Organogenesis refers to the differentiation of organs such as roots, shoots or flowers. Shoot bud differentiation may occur dire

Explain the taxonomic concepts, Q. Explain the taxonomic concepts? The ...

Q. Explain the taxonomic concepts? The history of classification is an exciting aspect of plant taxonomy. The discovery of the use of plants for food and later as medicine bega

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