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

Define the maintenance of weight loss, Define the Maintenance of Weight Los...

Define the Maintenance of Weight Loss? Once an individual has managed to lose weight to a desirable level, it must not be assumed that the weight loss will be maintained automa

Working of serotonergic cell bodies, Q. Working of serotonergic cell bodies...

Q. Working of serotonergic cell bodies? The major site of serotonergic cell bodies is in upper pons and the midbrain, specifically the median and dorsal raphe nuclei and to a l

What is adaptive radiation?, What is adaptive radiation? The Adaptive r...

What is adaptive radiation? The Adaptive radiation is the appearance of several other species from one common ancestral species that have spread to various regions or environme

Explain the concept behind freezing the milk, Concept behind Freezing the m...

Concept behind Freezing the milk Freezing the milk also alters its composition and properties to a great extent. Let us learn about these changes. As the milk freezes, it becom

Adverse effects of air pollution, Air pollution affects both living and non...

Air pollution affects both living and non-living matter. The effects can be classified as.

Human diseases caused by virus, Q. What are some human diseases caused by v...

Q. What are some human diseases caused by virus and what are their respective modes of transmission? The major viral diseases transmitted by respiratory secretions (cough, snee

What is waist-to-hip ratio, What is Waist-to-Hip Ratio? Waist-to-Hip Ra...

What is Waist-to-Hip Ratio? Waist-to-Hip Ratio (WHR) is defined as the measurement of waist circumference divided by hip circumference. For example, if a person's waist measure

Explain 1st type of hypersensitivity, It is IgE mediated hypersensitivity. ...

It is IgE mediated hypersensitivity. Typical manifestations contain asthma, food allergies, eczema, hay fever etc.

Porifera, method of digestion in porifera

method of digestion in porifera

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