ARE ALL PRODUCTS OF SPERMATOGENESIS REGULARLY FUNCTIONAL?

Abstract

It is generally accepted that the 4 products of meiosis in the male, of Drosophila as well as of most other animals, are functional, and this view is not inconsistent with the bulk of histological and genetic evidence available. The results of a simple genetic experiment with D. melanogaster cast some doubt on the universality of that generalization. The experiments were conducted to obtain information about the relative frequencies of the different kinds of sperm produced by males carrying the transloca-tion T(1,4)BS [Translocation (1,4) Bar of Stone]. This is a transloca-tion between the X chromosome and the minute 4th chromosome. The results suggest that if 2 unequal homologues are present in a male, the shorter may appear preferentially in the progeny, and the deviation from expectation may be so great that mortality can be excluded as the cause. Segregation of the components of a translocation in the male of Drosophila cannot be interpreted easily on the basis of our present assumptions about the nature of spermatogenesis and gamete behavior. It is suggested that in these cases, and in others cited, not all products of spermatogenesis are functional and, further, that this condition may not be limited to these special cases but may be generally true, being revealed only when certain experimental conditions are achieved.