In the present study we demonstrate the existence of two apoptotic patterns
in Drosophila nurse cells during oogenesis, One is developmentally regulat
ed and normally occurs at stage 12 and the other is stage-specific and is s
poradically observed at stages 7 and 8 of abnormally developed follicles, T
he apoptotic manifestation of the first pattern begins at stage 11 and is m
arked by a perinuclear rearrangement of the actin cytoskeleton and the deve
lopment of extensive lobes and engulfments of the nurse cell nuclei located
proximal to the oocyte, Consequently, at late stage 12 (12C), half of the
nurse cell nuclei exhibit condensed chromatin, while at late stage 13 all t
he nuclei have fragmented DNA, as it is clearly shown by TUNEL assay. Final
ly, the apoptotic vesicles that are formed during stage 13, are phagocytose
d by the neighboring follicle cells and at stage 14 the nurse cell nuclear
remnants can be easily detected within the adjacent follicle cell phagosome
s, In the second sporadic apoptotic pattern, all the nurse cell nuclei are
highly condensed with fragmented DNA, accompanied by a completely disorgani
zed actin cytoskeleton, When we induced apoptosis in Drosophila follicles t
hrough an etoposide and staurosporine in vitro treatment, we observed a sim
ilar pattern of stage-specific cell death at stages 7 and 8, These observat
ions suggest a possible protective mechanism throughout Drosophila oogenesi
s that results in apoptosis of abnormal, damaged or spontaneously mutated f
ollicles before they reach maturity.