What Is An Ova
Ova is the first and most primitive form of an organism. The ova contains half as many chromosomes as its parents. Hence it contains genes from both parents. This is the only stage where the germ cells are uncloistered, effortlessly combining with other germ cells.
The origin of OVA:
All living organisms have a fixed number of chromosomes in each cell. In the case of higher organisms, this fixed number consists of two sets of 23 chromosomes (46 total) – one set from the female parent and one from the male parent. All 46 chromosomes from both sexes pack into sex cells which then join to produce “ova.” Hence during formation, a single ova obtains half 23 chromosome sets – one paternal, one maternal.
The Ova formation:
Every organism goes through various stages of development, starting from embryo to fetus, then child, and finally an adult animal. However, the microorganisms mentioned above that produce ova are different from others in their life cycle.
Their life cycles start with growing into an adult animal which subsequently has offspring (ova). The significant difference is that the ovum carries half the number of chromosomes compared to other cells or animals in the same group.
When these animals reproduce, each parent contributes one set of 23 chromosomes to form a total complement of 46 chromosomes in sex cells (ovum). Two groups of sex cells, both containing 22 autosomes (non-sex chromosome) and one sex chromosome, unite during fertilization to form a zygote (fertilized egg) with two sets of 23 chromosomes.
The first stage in the formation is prophase I, whereas metaphase II marks the second stage. During both stages, the nuclear membrane breaks down to provide access for spindle fibers coming from opposite cell poles.
This way, all 46 chromosomes are pulled toward two separate poles to become haploid cells with 23 single sets of chromosomes each. After that, daughter nuclei are formed around by duplication of genetic material and then enter into prophase II again to pair off the chromosomes according to their similarity in structure and length during synapsis.
At telophase II, cytokinesis occurs to form two daughter cells, each having 23 single sets of chromosomes in a total of 46 chromosomes. This way, each cell formed has half the number of chromosomes compared to the original parent cell. Each daughter cell can develop into an individual organism, whereas the parental cell dies at this stage itself.
The process of ova formation is an interesting one, and it begins with the growth of an adult animal. Once the adult has reached its maturity, it will start to produce ova, which will be haploid cells carrying half the number of chromosomes compared to other cells in the body. These haploid cells undergo meiosis, where their numbers are reduced to 23 single sets of chromosomes.
Two such daughter cells will then form from the original parent cell, each containing 23 single packs of chromosomes in a total of 46 chromosomes. From here on, these two daughter cells can develop into separate organisms and grow into adults just like their parents did. This completes the life cycle for these animals that produce ova.