Fate of neuroblast progeny during postembryonic development of mushroom bodies in the house cricket, Acheta domesticus

Mushroom bodies represent the main sensory integrative center of the insect brain and probably play a major role in the adaptation of behavioral respo nses to the environment. Taking into account the continuous neurogenesis of cricket mushroom bodies, we investigated ontogenesis of this brain structu re. Using BrdU labeling, we examined the fate of neuroblast progeny during the postembryonic development. Preimaginal Kenyon cells survived throughout larval and imaginal moults and persisted during adulthood. Our results ind icate that the location of labelled Kenyon cells in the cortex of the adult cricket mainly depends upon the period when they were produced during deve lopment. The present data demonstrate that cricket mushroom bodies grow fro m the inside out and that, at any developmental stage, the center of the co rtex contains the youngest Kenyon cells. This study also allowed us to obse rve the occurrence of quiescent neuroblasts. Kenyon cell death during poste mbryonic and adult life seems to be reduced. Although preimaginal Kenyon ce lls largely contribute to adult mushroom body structure, a permanent remode ling of the mushroom body occurs throughout the whole insect life due to th e persistence of neurogenesis in the house cricket. Further studies are nee ded to understand the functional significance of these findings. (C) 2000 E lsevier Science Ltd. All rights reserved.