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 phylum sarcdina, Phylum Sarcdina 1) They move by means of pseud...

Phylum Sarcdina 1) They move by means of pseudopodia (ralse feet) or similar structures. 2) They feed heterotrophically by phagocytosis.   Some examples: Amoeba, Entamo

Explain the bioavailability of thiamin, Explain the Bioavailability of Thia...

Explain the Bioavailability of Thiamin? Thiamin is readily available from the gut from food sources (as thiamin phosphate esters). Drugs and alcohol abuse may interfere with th

Explain evidence of coverage of ecology, Explain Evidence of coverage of Ec...

Explain Evidence of coverage of Ecology Evidence of coverage of Ecology and Evolution to the level of Descriptor 2 and an evaluation or  discussion that shows depth of underst

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

How is the structure of a mitochondrion well adapted, How is the structure ...

How is the structure of a mitochondrion well adapted for the activities it carries out? The mitochondrial membranes segregate the enzymes and reactants of the Krebs cycle, faci

Describe the general guidelines for use of bone grafting, General guideline...

General guidelines for use of BONE GRAFTING 1. The surgical site should be prepared, that is it should be free of granulation tissue. 2. For autogenous grafts- the donor sit

Hypospadias, Hypospadias Hypospadias is the most common congenital an...

Hypospadias Hypospadias is the most common congenital anomaly of the penis. In this uretheral opening is situated on ventral side of the shaft of penis in one or several posi

Photoperiodism was first characterised, Photoperiodism was first characteri...

Photoperiodism was first characterised in : 1. Tobacco 2. Potato 3. Tomato 4. Cotton Tobacco is the first in whic photoperiodism characterised.

Explain the cori cycle, The  Cori cycle a)  Pyruvate formed from glucos...

The  Cori cycle a)  Pyruvate formed from glucose is converted  to lactate by lactate dehydrogenase in the muscle cell. b)  Lactate is released into  the blood and taken up b

In which organ red blood cells are stored, Surplus red blood cells, require...

Surplus red blood cells, required to meet an emergency, are generally stored in what organ of the human body? Is it the: a) Liver b) Spleen c) pancreas d) Kidneys

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