Types of Meiosis

Cells undergoing meiosis are called meiocytes.

Three types of meiosis.

Fig. Three types of Meiosis

(1) Gametic/Terminal Meiosis : Division takes place during gamete formation which fuse to form zygote. This type of meiosis results in diplontic life cycle and occurs in animals.

(2) Zygotic/Initial Meiosis : Division takes place in zygote and the resulting organisms have haplontic life cycle. Occurs in plants of thallophyta group.

(3) Sporic/Intermediate Meiosis : Division takes place during formation of spores resulting in diplohaplontic life cycle. Occurs in all plants except thallophyta.

Amitosis

Amitosis is also termed as Direct division because in this nucleus divides directly (without prophase, metaphase, anaphase and telophase) into two parts. Discovered by Remak and is a very primitive type of division.

Spindle fibres are not formed during the division.

There is no sequential change during the division.

The exchange of genetic material is not necessary during Amitosis.

A rapid division completed approximately in 20-30 minutes.

Division of prokaryotic animals (organisms), also occurs in some eukaryotes like yeast, ciliate protozoans and foetal membrane of vertebrates.