In the animal kingdom, the method of reproduction varies greatly, with many species laying eggs. The nature of these eggs, especially the distribution of yolk within them, can differ significantly. Generally, there are three types of eggs based on yolk distribution.
This article will delve into the specifics of telolecithal and centrolecithal eggs, highlighting their differences.
Telolecithal eggs are characterized by a large volume of yolk, unevenly spread throughout the cytoplasm, with a higher concentration towards the vegetal pole. Animals such as birds, reptiles and certain species of fish are known to lay telolecithal eggs.
In contrast, centrolecithal eggs have their yolk concentrated centrally within the shell, with a thin cytoplasmic layer encasing it. These eggs are typically laid by Arthropoda animals.
| Telolecithal Egg | Centrolecithal Egg |
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Definition |
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| Telolecithal eggs have a large amount of yolk unevenly distributed throughout the cytoplasm, with a higher concentration towards the vegetal pole. | Centrolecithal eggs have their yolk evenly distributed and centrally located within the shell. |
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Characteristic Feature |
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| The yolk is concentrated towards the vegetal pole. | A thin layer of cytoplasm surrounds the centrally located yolk. |
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Examples |
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| Birds, certain fishes and reptiles | Arthropods |
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What do you mean by Alecithal?
The eggs that have little or no yolk are referred to as alecithal eggs, such as human eggs.
What is a regulative egg?
An egg that does not have predetermined developmental potentialities is known as a regulative egg. Removal of a few blastomeres does not affect the development of such eggs.
What is a mosaic egg?
An egg that has predetermined developmental potentialities is known as a mosaic egg. Removal of any portion of the egg leads to the absence of the particular organ in the individual.