Question

Egg with large amount of yolk is
A. Microlecithal
B. Mesolecithal
C. Oligolecithal
D. Macrolecithal

Answer 1

Egg or ovum is a female gamete which is produced by the process oogenesis. It takes place in the ovary. Oogenesis is a type of gametogenesis. Egg contains cytoplasm and yolk. The amount of the yolk determines the size of the egg.

Complete answer:
On the basis of the proportion of the yolk to the cytoplasm of the egg or ovum, it is divided into different types. These are microlecithal, mesolecithal and macrolecithal. The egg yolk performs various functions. It supplies energy and makes the products required for the development of the embryo. The yolk also has an important influence on the size of the ovum, patterns of mitotic divisions and the type of development whether direct or indirect.
Microlecithal egg:
In microlecithal eggs the amount of yolk is very less as compared to the amount of cytoplasm. Thus microlecithal eggs are very small in size. Microlecithal eggs are also considered as oligolecithal eggs. The eggs of Amphioxus, eutherian mammals and kangaroo’s eggs are microlecithal
Mesolecithal eggs:
In this type of egg, yolk is in moderate amounts and the distribution of yolk is unequal. The eggs of sharks, dipnoi and many amphibians are mesolecithal.
Macrolecithal eggs:
In this type of eggs the amount of yolk is many times larger than the cytoplasm. These eggs may be small or big. The eggs of legless amphibians), reptiles, birds and egg laying mammals are macrolecithal.

Thus, option D. Macrolecithal is the correct answer.

Note: The macrolecithal eggs have large amounts of egg yolk. The yolk supplies energy and makes the products required for the development of the embryo.