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Amitosis

 

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قابل توجه دانشجویان کلاس زیست شناسی جانوری

In some organismsthe nucleus of the parent divides into many daughter nuclei by repeated divisions (amitosis). This is followed by the division of the cytoplasm into several parts with each part enclosing one nucleus. So a number of daughter cells are formed from a single parent at the same time. This kind of fission is known as multiple fission.

Example: Seen in Plasmodium (malarial parasite) where it is known as schizogony or sporulation, amoeba.

multiple fission in amoeba and malarial parasite
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Amitosis : a - absence : mitos - thread) no thread formation

 1. Amitosis Direct nuclear division) was first reported in F?BC of chick embryo by Robert Remak (1341), It is characterised by absence of distinct chromosomes and spindle apparatus.

2, During amitosis, the nucleus moves to the centre and elongates. As the elongation of nucleus proceeds, it attains dumbell shape. At the same time, there appears a constriction in the middle of the cell, which later deepens. It results in division of cytoplasm into two equal parts. The nuclcar division along with cytoplasmic division results in two daughter cells. Amitosis occurs in prokaryotes certain cukaryotic cells and cells of the foetal membrane

Significance of Meiosis
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 Amitosis. Amitosis is often referred to as direct cell division. It is a type of cell division where the cell breaks into two parts by constriction of the nucleus and cytoplasm. There may be unequal distribution of the chromosomes. This type of cell division occurs in the placenta and in the surface cells of transitional epithelium.

 

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