Morphological changes, Biology

Assignment Help:

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.

 


Related Discussions:- Morphological changes

Explain uristix benedicts test, Q. Explain Uristix Benedicts test? No s...

Q. Explain Uristix Benedicts test? No sugar/glucose is excreted in the urine in normal individuals. In diabetics, glucose is excreted by the kidneys when the blood sugar levels

Which kind of gamete produced by a heterozygous individual, Which is the ki...

Which is the kind of gamete produced by a heterozygous individual? And what is the genotypical proportion of these gametes? The Heterozygous individuals, for instance, AA, prod

What is linkage, Question Write a short note on the following: 1 D...

Question Write a short note on the following: 1 Dihybrid cross 2 Supplementary interaction 3 Maternal effect 4 Hardy Weinberg Equilibrium 5 What is Linkage? Ex

Gene clonning, Inportant step for gene clonning

Inportant step for gene clonning

Whether the drug-susceptible or drug-resistant phenotype, True or false? It...

True or false? It would be difficult to assess whether the drug-susceptible or drug-resistant phenotype in a population of Mycobacterium tuberculosis was more fit in an environment

Circulatory assist devices-open-heart surgery, Circulatory Assist Devic...

Circulatory Assist Devices :  Intra aortic balloon pump (IAUP) was introduced by Kantrowitz (19hX). It is also known as Counter pulsation or Diastolic augmentation.

Why pregnancy and lactation are critical stages in lifecycle, Why Pregnancy...

Why Pregnancy and lactation are critical stages in lifecycle? You must be aware that the situation of women is far from optimal and it is necessary to give attention to their n

Genetic abnormalities caused by recessive genes, What are some diseases or ...

What are some diseases or genetic abnormalities caused by recessive genes? Instance of recessive genetic diseases are: cystic fibrosis, phenylketonuria, albinism, galactosemia,

What is thermoregulation in cold, What is Thermoregulation in Cold? Hea...

What is Thermoregulation in Cold? Heat production parallels the increase in O 2 uptake, the magnitude of which depends on the muscle mass .engaged in slivering or work and the

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