Genital disc growth in Drosophila.

Prior to completion, apoptosis causes the secretion of different signals, including proliferative signals. Signaling associated with death was discovered in Drosophila and mostly characterized by the induction of experimental death. Thus, less is known about physiological death. Here, we analyzed physiological death in the genital disc, a structure with bilateral symmetry, in different growth scenarios. To this end, we prevented or promoted death in regions or in genetic mosaics. We observed that physiological death in the genital disc was associated with proliferative signals and that both processes were JNK-dependent. The proliferative signals promoted growth in the genitalia primordia but not in the analia. Due to the proliferative signaling, the prevention of death that produced undead cells provoked asymmetric growth, high variability in proliferation, and size reduction. Death can occur in the absence of JNK but without signaling. JNK is fundamental for growth and death associated with signaling.