Postembryonic development of the lateral protocerebral lobes, corpora pedunculata, deutocerebrum and tritocerebrum of Phormia regina meigen (diptera: calliphoridae)

Abstract

The postembryonic development of the corpora pedunculata, deutocerebrum and tritocerebrum of Phormia regina Meigen was studied using reduced silver stains to provide detailed observations and determine the relationships between larval and imaginal neurones. The imaginal ganglion cells of these areas are formed from isolated neuroblasts by a series of asymmetric and symmetric divisions. The imaginal corpora pedunculata are formed by 10 isolated neuroblasts located dorsal to the larval calyces. The imaginal antennal ganglia are formed by 2 isolated neuroblasts. These ganglia lie dorsal to the larval antennal ganglia which degenerate during the late larval and early pupal stages. The glomerular structure of the imaginal ganglia develops during the pupal stage after receiving antennal sensory fibers. The tritocerebrum of the imaginal brain is formed by isolated neuroblasts. The cellular and neuropilar components of the larval brain degenerate during the late larval and early pupal stages. The degenerating larval ganglion cells are characterized by pycnotic nuclei and the neuropile by a ragged, darkly stained appearance. The larval and adult brains of Phormia are discrete morphological entities as revealed by the degeneration of the larval brain, concomitant with its replacement by corresponding imaginal elements.