● Further investigations by other scientists led to the conclusion that the `color{Violet}"X body"` of `color{Violet}"Henking"` was in fact a chromosome and that is why it was given the name `color{Violet}"X-chromosome"`.

● It was also observed that in a large number of `color{Violet}"insects"`, the mechanism of sex determination is of the `color{Violet}"XO type"`, i.e., all eggs bear an `color{Violet}"additional X-chromosome"` besides the other chromosomes (autosomes).

● On the other hand, some of the `color{Violet}"sperms"` bear the `color{Violet}"X-chromosome"` whereas `color{Violet}"some do not"`.

● Eggs fertilised by sperm having an `color{Violet}"X-chromosome"` become `color{Violet}"females"` and, those fertilised by sperms that `color{Violet}"do not"` have an `color{Violet}"X-chromosome"` become `color{Violet}"males"`.

● Due to the involvement of the X-chromosome in the `color{Violet}"determination of sex"`, it was designated to be the `color{Violet}"sex chromosome"`, and the rest of the chromosomes were named as `color{Violet}"autosomes"`.

● `color{Violet}"Grasshopper"` is an example of `color{Violet}"XO"` type of sex determination in which the males have only one X-choromosome besides the autosomes, whereas females have a pair of X-chromosomes.

● These observations led to the `color{Violet}"investigation"` of a `color{Violet}"number of species"` to understand the mechanism of sex determination.


● In some other organisms, e.g., `color{Violet}"birds"` a different mechanism of sex determination is observed .

● In this case the total `color{Violet}"number of chromosome"` is same in both `color{Violet}"males and females"`.

● But `color{Violet}"two different"` types of gametes in terms of the sex chromosomes, are produced by females, i.e., `color{Violet}"female heterogamety"`.

● In order to have a `color{Violet}"distinction"` with the mechanism of sex determination described earlier, the two different sex chromosomes of a `color{Violet}"female bird"` has been designated to be the `color{Violet}"Z and W chromosomes"`.

● In these organisms the females have `color{Violet}"one Z and one W"` chromosome, whereas males have a `color{Violet}"pair of Z-chromosomes"` besides the autosomes.


● It has already been mentioned that the `color{Violet}"sex determining mechanism"` in case of `color{Violet}"humans is XY"` type.

● Out of 23 pairs of chromosomes present, `color{Violet}"22 pairs"` are exactly `color{Violet}"same"` in both males and females; these are the `color{Violet}"autosomes"`.

● A `color{Violet}"pair of X-chromosomes"` are present in the female, whereas the presence of an `color{Violet}"X and Y chromosome"` are determinant of the male characteristic.

● During `color{Violet}"spermatogenesis"` among males, `color{Violet}"two types"` of gametes are produced.

● `color{Violet}"50 per cent"` of the total sperm produced carry the `color{Violet}"X-chromosome"` and the rest `color{Violet}"50 per cent"` has `color{Violet}"Y-chromosome"` besides the autosomes.

● Females, however, produce only `color{Violet}"one type of ovum"` with an X-chromosome.

● There is an `color{Violet}"equal probability of fertilisation"` of the ovum with the sperm carrying either X or Y chromosome.

● In case the ovum fertilises with a sperm carrying `color{Violet}"X-chromosome"` the zygote develops into a `color{Violet}"female (XX)"` and the fertilisation of ovum with `color{Violet}"Y-chromosome"` carrying sperm results into a `color{Violet}"male offspring"`.

● Thus, it is evident that it is the `color{Brown}"genetic makeup of the sperm"` `color{Violet}"that determines the sex of the child"`.

● It is also evident that in each pregnancy there is always `color{Violet}"50 per cent probability"` of either a male or a female child.

● It is unfortunate that in our society `color{Violet}"women are blamed"` for producing female children and have been ostracised and ill-treated because of this false notion.