Determination Of Sex

Determination Of Sex

TYPES OF CHROMOSOMES:

Chromosomes are of two types:

• Autosomes or Somatic chromosomes: These regulate somatic characters.
• Allosomes or Heterosomes or Sex chromosomes: These chromosomes are associated with sex determination. Sex chromosomes were discovered by "Mc Clung" in grasshopper. X- Chromosome was discovered by Henking and called as x - body by him.

X X - XY TYPE:

This type of sex determination was first observed by Wilson and Stevens in Lygaeus insect. It is of two types:

• X X female and XY male: In this type of sex determination female is homogametic while males are heterogametic. e.g. Humans.

• XY female and XX male: In this type of sex determination female is heterogametic while males are homogametic. e.g. Butterflies, moth and vertebrates like birds, fishes and reptiles.

XX FEMALE AND XO MALE:

In this type of sex determination their occurs deficiency of one chromosome in male. In this type female is homogametic and male is heterogametic. e.g. Grasshopper and Cockroach etc.