Neurons projecting to the retrocerebral complex of the adult blow fly, Protophormia terraenovae

Abstract

Anatomical study of neurons projecting to the retrocerebral complex of the adult blow fly, Protophormia terraenovae, was done by NiCl2 filling and immunocytochemistry. Retrograde filling through the cardiac-recurrent nerve labeled three groups of neurons in the brain/subesophageal ganglion: (1) paramedial clusters of the pars intercerebralis, (2) neurons in each pars lateralis, and (3) neurons in the subesophageal ganglion. The pars intercerebralis neurons send prominent axons into the median bundle and exit from the brain via the contralateral nervus corporis cardiaci. Based on the projection pattern, two types of the pars lateralis neurons can be distinguished: the most lateral pairs of neurons contralaterally extend through the posterior lateral tract and the remainder ipsilaterally extend through the posterior lateral tract. The neurons in the subesophageal ganglion run through the contralateral nervus corporis cardiaci. The dendritic arborization of the pars intercerebralis and pars lateralis neurons is restricted to the superior protocerebral neuropil and to the anterior neuropil of the subesophageal ganglion where the neurons in the subesophageal ganglion also project. Retrograde filling from the corpus allatum indicated that the pars lateralis neurons and a few pars intercerebralis neurons project to the corpus allatum, but that the neurons in the subesophageal ganglion do not. Orthograde filling from the pars intercerebralis and staining by paraldehyde-thionin/paraldehyde-fuchsin indicated that the pars intercerebralis neurons project primarily to the corpus cardiacum/hypocerebral ganglion complex. Immunostaining with a polyclonal antiserum against diapause hormone, a member of the FXPRLamide family, suggests that some of the subesophageal ganglion neurons contain FXPRLamide-like peptides.

Pyrokinin/PBAN-like peptides in the central nervous system of Drosophila melanogaster

“…An antiserum raised against the diapause hormone of B. mori and recognizing the FXPRLamide family of peptides was used in a study of the adult blow fly, Protophormia terraenovae, by Shiga et al (2000). They found a set of four-cell clusters in the adult SEG similar to those that we found in D. melanogaster.…”

“…We did not observe the small somata in the median bundle of D. melanogaster but did find the projections from the dorsal neurons into the median bundle of the brain. The study with the blow fly was not concerned with localization of FXPRLamide peptides in other parts of the nervous system nor in larval stages, and therefore only the adult brain was studied (Shiga et al 2000). However, it appears that pyrokinin/PBAN-like peptides are present in several different species of flies.…”

Factors that regulate insulin producing cells and their output in Drosophila

“…In addition there are bilateral clusters of peptide-producing lateral neurosecretory cells (LNCs; Figure 3) that also send axons to the corpora cardiaca/allata, aorta and anterior gut structures (often referred to as the retrocerebral complex). The LNCs in some cases have collateral processes that superimpose the proto- and tritocerebral processes of the median neurosecretory cells (Figures 2B,C, 3) or converge with them in the retrocerebral complex (see Homberg et al, 1991; Shiga et al, 2000; Siegmund and Korge, 2001; Hamanaka et al, 2007; Kapan et al, 2012). Several of the LNCs produce peptides that are released as circulating hormones, others may produce peptides that act more locally as regulators of release from MNCs (detailed in the next section).…”

Neuroanatomical Approaches to the Study of Insect Photoperiodism†

“…Neurons innervating the CA were examined by retrograde dye fills. Injection of dye into the CA revealed neurons with somata in the PI and PL (79). Intracellular dye fills to somata in the PI and PL revealed two types of neurons densely innervating the CA (80).…”

“…There are 14–19 PL neurons and a large number of PI neurons in each cerebral hemisphere sending axons to the CC or CA, or to both in P. terraenovae (79). Synaptic connections between PL and PDF‐immunoreactive neurons were sparsely observed, indicating that only a small number of PL neurons receive synaptic input from PDF‐immunoreactive neurons.…”