Morphological changes, Biology

Morphological changes

Regressive changes-These changes include the gradual reduction and ultimate disappearance of all those larval structures or organs that become redundant in adults. The ventral suckers, external gills, the long tail along with fin folds are reabsorbed during early functional life. The peribranchial cavities, the gill clafts are closed; the horny teeth and horny lining of the jaws are lost. The shape of the mouth changes, the cloacal tube shortens and gets reduced. The lateral line organs of the skin of tadpole disappear and some blood vessels are reduced.

Progressive changes-A number of organs and structures become functional during and after metamorphosis. In the anurans these alters are tabulated in Table and include the development of the fore and the hind limbs, the middle ear in connection with the first pharyngeal pouch (the pouch situated among the mandibular and hyoid arches), the tympanic membrane supported through the circular tympanic cartilage. The eye protrudes on the dorsal surface of the head and makes an upper eyelid. The tongue develops from the floor of the mouth.

Remodeling -Some structures and organs that occur and function both before and after metamorphoses, get transformed or remodeled throughout the process in order to meet the requirement of the adult mode of life. These changes, affect primarily the skin, intestine and brain. The skin thickens, and turns into glandular by developing multicellular mucous and serous glands. It also develops an outer keratinized layer also characteristic color and pattern of pigmentation. The brain gets highly differentiated. The intestine that was long and coiled in the herbivorous tadpole shortens and straightens out: Other notable changes which take place are the change in the blood vascular system in order to supply the lungs, the change in the portal system the alteration in the heart as it becomes three chambered from being two chambered earlier.

 

Posted Date: 1/30/2013 6:06:13 AM | Location : United States







Related Discussions:- Morphological changes, Assignment Help, Ask Question on Morphological changes, Get Answer, Expert's Help, Morphological changes Discussions

Write discussion on Morphological changes
Your posts are moderated
Related Questions
What is the Endoplasmic Reticulum The cytoplasm of most eukaryotic cells contains a very complex network of internal membranes, called the endoplasmic reticulum, which forms ch

Fischer 's template or lock and key model According to this model, the catalytic site of the enzyme has a proper conformation compatible to a specific substrate even  in  the a

African swine fever African swine fever (ASF), a highly contagious viral disease of swine and other porcine animals (generally confined to the African continent, part of Weste

R E TIN A - It is inverted. Innermost, sensitive layer. The part of ratina which is attached to choroid is pars optica. The part of retina attached to cilliary b

Define Buffers and Buffer Solutions? Solutions containing both weak acid and their salts or solutions containing weak hydroxides and their salts are referred to as buffer solut

Which of the following is true for a G-protein? A. When an agonist binds to the binding site of a G-protein-coupled receptor (GPCR), this leads to GDP displacing a GTP bound to

What is the difference between embryo and endosperm?

Describe Basic steps in genetic engineering

Compare and contrast the effect of a deletion in the operator of the lactose operon with one in the operator of the histidine operon.

Explain Whipping foam method? Whipping is the most common method used as it forms bubbles by cutting the surface and introducing air into liquid.  Repeated action makes the