CONTROL OF CELL-PROLIFERATION IN THE CORPORA ALLATA DURING THE REPRODUCTIVE-CYCLE OF THE COCKROACH DIPLOPTERA-PUNCTATA

Unlike in Blettella germanica and Supella longipalpa, the corpora alla ta (CA) of Diploptera punctata exhibited cyclic changes in cell number during the reproductive cycle. In mated females, a wave of DNA synthe sis followed by mitosis resulted in a significant increase in CA cell number from about 9,000 cells on day 0 to 12,000 cells at ovulation on day 8. Subsequently, the number of cells per CA underwent a gradual d ecline to about 10,000 cells by day 64. During this long period of ges tation, mitotic activity was undetectable (by colchicine arrest) and p ycnotic nuclei were frequently observed by transmission electron micro scopy. Just before parturition on day 72 another mitotic wave was dete cted and CA cell number increased again. The early wave of CA cell pro liferation could be postponed by delaying mating or abolished by maint aining females as virgins. Neural disconnection of the CA from the bra in mimicked the effect of mating, suggesting that enhanced cell prolif eration is permitted by the removal of inhibitory signals from cerebra l neurosecretory cells. The proliferative activities after mating were neither abolished by ovariectomy, which suppressed the normal increas e in JH synthesis, nor elevated by unilateral allatectomy, which doubl ed the rates of JH synthesis in the remaining CA. These data corrobora te previous results (Szibbo and Tobe, 1981a; Tobe et al., 1984; Johnso n et al., 1993) and suggest that waves of cell proliferation and JH sy nthesis, though simultaneous, are regulated independently by inhibitor y signals from cerebral neurosecretory cells. (C) 1996 Wiley-Liss, Inc .