The major niche for generation of new neurons in adult brain surrounds the lateral ventricles. In this local there is a group of cells with unique morphology and derivated from specific steps of proliferation process and cell diferentiation, that will generate the neuron. However, the description of cell that initiates the proliferation in this region is still controversial. In this way, to corroborate the ultrastructural characterization of the cells, mainly that entered in cycle of division, can contribute to solve the debate. Furthermore, the compartmentalization of periventricular region leads to a pattern of distribution for axonal fibers, as that transmit the neuroactive peptide CART, which description of its innervation and its relationship with cells of this neurogenic niche may highlight perspectives for understand the putative role of this modulator factor in the periventricular neurogenic niche. So, we aim: 1) to study the cytoarchitecture in ultrastructural level of BrdU immunoreactive (ir) cells located in periventricular region; 2) to colaborate for comprehension of tridimensional in situ organization of this region and 3) to describe the innervation of CART-ir axonal fibers and putative apositions stablished with canonical cells of periventricular region. We used Long-Evans rats and C57Bl6 and GFAP:GFP mice, adults. The animals were perfused with different fixative solutions for further ultrastructural analysis of cell morphology and neurochemistry in the periventricular region of brain, by transmission and high-resolution scanning electron microscopes, light and laser confocal. The study of proliferation at periventricular region occured after delivery of 2% arabinofuranoside (Ara-C) and the mitotic cell cycle marker BrdU (50 mg/kg, i.p.). The immunohystochemistry investigation used the primary antibodies anti-BrdU, anti-CART, anti-DCX, anti-GFAP and anti-GFP. The entire cells in periventricular region were BrdU-ir, but with variation in density of staining. We observed these occurying in ventricule linning corresponded to ependymal cells, tanycytes and astrocytes. These cells are heterogeneous in density of cillia distribution, presenting single, bi or multi-ciliated, besides be innervated in its apical surface by varicosal axons. We found the major density of CART-ir innervation in migratory path of neurons in formation and that these axons stablished apositions among neural primary progenitors, neuroblasts and cell that entered the S-phase of mitotic cycle. Therefore, 1) all cells of periventricular niche are BrdU-ir; 2) the tridimensional in situ a organization of lateral ventricle highlights the heterogeneity in density of ciliary implantation and a dense varicosal innervation apposed to the different cilia; 3) anatomical evidences suggest a role for the regulator peptide CART in periventricular neurogenesis.
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