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Nogo is a member of the reticulon family. Our understanding of the physiological functions of the Nogo-A protein has grown over the last few years, and this molecule is now recognized as one of the most important axonal regrowth inhibitors present in central nervous system (CNS) myelin. Nogo-A plays other important roles in nervous system development, epilepsy, vascular physiology, muscle pathology, stroke, inflammation, and CNS tumors. Since the exact role of Nogo-A protein in human brain development is still poorly understood, we studied its cellular and regional distribution by immunohistochemistry in the frontal lobe of 30 human fetal brains. Nogo-A was expressed in the following cortical zones: ependyma, ventricular zone, subventricular zone, intermediate zone, subplate, cortical plate, and marginal zone. The number of positive cells decreased significantly with increasing gestational age in the subplate and marginal zone. Using different antibodies, changes in isoform expression and dimerization states could be shown between various cortical zones. The results demonstrate a significant change in the expression of Nogo-A during the development of the human brain. The effects of its time- and region-specific regulation have to be further studied in detail. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Caveolae are microinvaginations of the cell plasma membrane involved in cell transport and metabolism as well as in signal transduction; these functions depend on the presence of integral proteins named caveolins in the caveolar frame. In the brain, various caveolin subtypes have been detected in vivo by immunocytochemistry: caveolin-1 and -2 were found in rat brain microvessels, caveolin-3 was revealed in astrocytes. The aim of this study was to identify the site(s) of cellular expression of caveolin-1 in the microvessels of the human cerebral cortex by immunofluorescence confocal microscopy and immunogold electron microscopy. Since in the barrier-provided brain microvessels tight relations occur between the endothelium–pericyte layer and the surrounding vascular astrocytes, double immunostaining with caveolin-1 and the astroglia marker, glial fibrillary acidic protein, was also carried out. Immunocytochemistry by confocal microscopy revealed that caveolin-1 is expressed by endothelial cells and pericytes in all the cortex microvessels; caveolin-1 is also expressed by cells located in the neuropil around the microvessels and identified as astrocytes. Study of the cortex microvessels carried out by immunoelectron microscopy confirmed that in the vascular wall caveolin-1 is expressed by endothelial cells, pericytes, and vascular astrocytes, and revealed the association of caveolin-1 with the cell caveolar compartment. The demonstration of caveolin-1 in the cells of the brain microvessels suggests that caveolin-1 may be involved in blood–brain barrier functioning, and also supports co-ordinated activities between these cells. [Copyright &y& Elsevier]

Intraventricular transplants of neural tissues were performed in ovo from embryo to embryo. Fragments of the nervous wall of the optic lobe (tectum) from 14-day chick or 12-day quail embryos (donor) were inserted into the ventricle of the right optic lobe of 6-day chick or 5-day quail embryos (host). Chick-to-chick, chick-to-quail and quail-to-chick grafts were carried out. The vascularization changes occurring in the host tectum and in the grafted neural tissues were analysed under light, transmission, and scanning electron microscopes and by morphometric methods. In the host embryo tectum, the neural graft stimulates a statistically significant increment in vessel density and a vessel sprouting into the ventricle of the optic lobe. The vascular sprouts reach the transplanted tissue and establish connections with its native microvasculature. The chick-to-quail and quail-to chick grafts, submitted to immunoreaction with a quailspecific antibody which recognizes an antigen (MB1) present on endothelial cells, indicate that re-establishment of the circulation in the graft depends upon anastomoses between host and donor vasculatures and the rapid new growth of host-derived and donor-native vessels. The presence of macrophage-like cells escorting the new-growing vessels suggests that these cells are involved in the host and donor tissue angiogenesis. [ABSTRACT FROM AUTHOR]