Abstract
The present paper deals with the histological and cytological observations of six male tortoiseshell cats. The four of these specimens possessed apparently sterile testes consisting of sterile seminal tubules which contained a few germ cells without any spermatogenetic activity.
In the testes of two males active spermatogenesis seemed to be proceeding in a regular fashion. The chromosomes of these cats showed nothing different from those in normal cats, either in their number or in their morphology or behavior. There are 38 chromosomes in a 2n complex including an X-Y pair and 19 in a n complex.
The results of the present observations have failed to demonstrate cytologically the X-Y crossing-over hypothesis postulated by Komai (1952).
