Changes in the egg of the tsetse fly, Glossina palpalis palpalis (Diptera: Glossinidae), after fertilization by sperm of gamma-irradiated males

This study was undertaken to establish the pattern of normal embryonic development as a basis for comparing aberrant development that may occur when females are mated to radio-sterilized males. Seven- to ten-day-old males of G. p. palpalis (Nigerian origin) were irradiated in air with 12-13 krad gamma rays from a 60Co source. Three hours after treatment they were allowed to mate with two-day-old normal females. Reproductive organs from females mated with treated males and with normal males were removed at regular intervals (starting on the eighth day following emergence) and examined by histological techniques. Extruded eggs were also examined. Development of most eggs fertilized by sperm of irradiated males was inhibited in cleavage and lytic processes took place on the following days. In eggs that ceased to develop and were later expelled at irregular intervals, the chorion was separated from the choriothete prior to extrusion. The occasional findings that embryogenesis was not interrupted until advanced stages or that normal embryonic and larval development was completed, indicate that treatment doses of 12-13 krad do not entirely damage the genetic material of the nucleus of sperm, or that repair is possible to some extent. Cyclic changes of the choriothete during pregnancy, its secretion and changes observed during this study, imply that, besides facilitating nidation of the egg in the uterus, the choriothete might function in folding of the chorion on the ventral floor of the uterus. (author)