AP183F Sigma-AldrichGoat Anti-Rat IgG Antibody, FITC conjugate, Species Adsorbed

An early and fundamental step of the laminar organization of developing neocortex is controlled by the developmental programs that critically depend on the activities of reelin-positive cells in the marginal zone. However, the ontogeny of reelin-positive cells remained elusive. To gain insights into the spatial and temporal regulation of reelin-positive marginal zone cell development, we used a transgenic mouse line in which we defined the green fluorescent protein (GFP) transgene as a novel reliable molecular marker of reelin-positive marginal zone cells from the early stages of their development. We further used exo utero electroporation-mediated gene transfer that allows us to mark progenitor cells and monitor the descendants in the telencephalon in vivo. We show here the generation of reelin-positive marginal zone cells from the caudomedial wall of telencephalic vesicles, including the cortical hem, where the prominent expression of GFP is initially detected. These neurons tangentially migrate at the cortical marginal zone and are distributed throughout the entire neocortex in a caudomedial-high to rostrolateral-low gradient during the dynamic developmental period of corticogenesis. Therefore, our findings on reelin-positive marginal zone cells, in addition to the cortical interneurons, add to the emerging view that the neocortex consists of neuronal subtypes that originate from a focal source extrinsic to the neocortex, migrate tangentially into the neocortex, and thereby underlie neural organization of the neocortex.

Monoamine oxidase type A and type B are major neurotransmitter-degrading enzymes in the CNS. The type A is present on mitochondrial outer membranes in the whole extent of noradrenergic and dopaminergic neurons, including their axon terminals. The type B is present in serotonergic neurons, but its subcellular localization has not been elucidated. In the present study, we used both a double-labeling immunofluorescence method and electron microscopic immunohistochemistry to examine the subcellular localization of monoamine oxidase type B in serotonergic neurons projecting from the dorsal raphe nucleus to the suprachiasmatic nucleus in the rat brain. In the dorsal raphe nucleus, serotonin-positive neuronal cell bodies were clustered, and virtually all of these cell bodies were also positive for monoamine oxidase type B. By contrast, serotonin-negative neuronal cell bodies were mostly free of this enzyme. Within the neuronal cell bodies and dendrites that were positive for monoamine oxidase type B, most mitochondria contained this enzyme on their outer membranes, but a substantial proportion of mitochondria lacked this enzyme. In the suprachiasmatic nucleus, serotonin-positive varicosities were concentrated, but none of these varicosities exhibited monoamine oxidase type B. In this nucleus, mitochondria were found in almost all serotonin-positive axon terminals, but monoamine oxidase type B was not observed in any axon terminal that contained mitochondria. Our results show that there are two kinds of mitochondria in serotonergic neuronal cell bodies and dendrites: one containing monoamine oxidase type B on their outer membranes, and the other lacking this enzyme. In addition, mitochondria in serotonergic axon terminals do not possess monoamine oxidase type B. It is suggested in serotonergic neurons that only mitochondria lacking monoamine oxidase type B are transported by axonal flow up to axon terminals. It is also probable that mitochondria containing monoamine oxidase type B are transported along the axons, but that this enzyme undergoes a change, for example, conformational change, decomposition or removal from the membranes.

The aim of the present study is to examine whether serotonergic fibers of the striatum of the rat contain aromatic L-amino acid decarboxylase (AADC). By use of a double-labeling immunofluorescence method, we showed that AADC was localized in serotonergic fibers of the striatum and cerebral cortex as well as in serotonergic cell bodies of the midbrain raphe nuclei. We previously demonstrated that serotonergic fibers of the rat striatum contained dopamine after intraperitoneal injection of L-dopa. These findings suggest that dopamine is produced from the injected L-dopa in serotonergic fibers of the rat striatum.

Pulmonary endocrine cells of Syrian golden hamster were stained for neural cell adhesion molecule (NCAM) with indirect fluorescent immunostaining and observed with a confocal laser scanning microscope equipped with an argon laser. Sections 100 microns thick of hamster lung fixed with phosphate-buffered 4% paraformaldehyde were prepared. The sections were incubated with rat monoclonal antibody against NCAM, followed by fluorescence-labeled antibody against rat immunoglobulin. Some were doubly immunostained for NCAM and one of the following endocrine markers: neuron-specific enolase, calcitonin gene-related peptide and serotonin. Expression of NCAM in the hamster airway epithelium was seen in cell nests resembling neuroepithelial bodies (NEBs). NCAM immunostaining was positive at the lateral cell borders between the cells composing the nest, but negative at the border with the adjacent, presumably non-endocrine cells. Double immunostaining confirmed that the grouped cells with NCAM immunoreactivity were of an endocrine nature, but that single endocrine cells did not show NCAM immunoreactivity. An electron microscopic study with NCAM immunostaining confirmed the light microscopic study. These suggest that NCAM expression could be important for the morphogenesis of NEBs. A confocal laser microscope was used to make three-dimensional images of NEBs after NCAM immunostaining and the spatial interaction between NEBs and the surrounding microenvironment was studied.