PRINCIPLES OF INHERITANCE AND VARIATION

. S EX D ETERMINATION The mechanism of sex determination has always been a puzzle before the geneticists. The initial clue about the genetic/chromosomal mechanism of sex determination can be traced back to some of the experiments carried out in insects. In fact, the cytological observations made in a number of insects led to the development of the concept of genetic/chromosomal basis of sex-determination.

Henking ( ) could trace a specific nuclear structure all through spermatogenesis in a few insects, and it was also observed by him that per cent of the sperm received this structure after spermatogenesis, whereas the other per cent sperm did not receive it. Henking gave a name to this structure as the X body but he could not explain its significance. Further investigations by other scientists led to the conclusion that the ‘X body’ of Henking was in fact a chromosome