Oogenesis
The formation of the ovum (mature female gamete) from undifferentiated germ cells is called oogenesis. This process takes place in the ovaries (female gonads). Oogenesis consists of three stages known as the multiplication phase, growth phase, and maturation phase.
Cell Division
Cell division involves the formation of new daughter cells from the parent cells. It is a part of the cell cycle that takes place in both prokaryotic and eukaryotic organisms. Cell division is required for three main reasons:
No disjunction is the reason we get chromosome number anomalies. Explain?
Chromosomes are present in the nucleus of the cell and are actually a compilation of the cell’s DNA. DNA carries the genetic information and helps to maintain heridity. In human there are 23 pairs of chromosomes present. In few rare cases some anomalies occurs that may cause change in the number of the chromosomes or change the ploidy level of the cell among them one is Non disjunction. This is mainly caused when the sister chromatids are unable to separate during the anaphase of cell division leading to one cell having more number of chromosome and the other cell having less chromosome number.
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