|(Level 1) Associate Educator
According to the chromosomes theory of sex determination, the male and female individuals would differ in their chromosome constitution. There may be two types of chromosomes present in such individuals: (1) autosomes, and (2) sex chromosomes. In a diploid individual, there are 2n-2 autosomes and two sex chromosomes. The experiments of C.B. Bridges on the nondisjunction of X-chromosomes proved that a diploid set of autosomes with two X-chromosomes will always give rise to a female individual irrespective of whether the two X-chromosomes came from the same parent.The above example illustrate that the Y -chromosome does not carry any sex determining factor. The presence of one or two X-chromosomes is more important than the presence or absence of Y-chromosomes.