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G Alvarez-Bolado

Publications and source records attributed to G Alvarez-Bolado.

24 records · Page 2Linked to original sources
PubMed1991

Prenatal development of the intrinsic neurons of the rat neocortex: a comparative study of the distribution of GABA-immunoreactive cells and the GABAA receptor.

The ontogenesis of cells showing GABA-like immunoreactivity, and the distribution of the immunoreactivity for the GABAA receptor were studied immunocytochemically in the prenatal rat brain. By embryonic day 14, a few GABA-like immunoreactive (GABA-positive) cells scattered at the subpial limit of the marginal zone (primordial plexiform layer) in the lateral part of the developing cortex. GABA-positive cells appeared progressively within the dorsal and medial sectors of the primordial plexiform layer, occupying deeper positions within the layer. The immunoreactivity for the GABAA receptor covered the whole thickness of the primordial plexiform layer. By embryonic day 16, most GABA-positive cells populated three distinct laminar compartments of the developing cortex: the prospective lamina I, the subplate, and the lower part of the intermediate zone. The GABA-positive cells of the lower intermediate zone appeared to be typical of the developing cerebral cortex of the rat: their neuronal nature was assessed immunocytochemically, using monoclonal antibodies against microtubule-associated protein 2, mainly expressed in neuronal somata and dendrites, and against intermediate filament protein vimentin, expressed in glia. The lower intermediate zone contained cells immunoreactive for microtubule-associated protein 2, although the immunostaining was less intense than in the prospective lamina I and the subplate. Preliminary results showed no vimentin-positive cells in the lower intermediate zone. At embryonic day 16, immunoreactivity for the GABAA receptor was present within the prospective lamina 1 and the subplate. Preliminary results showed no vimentin-positive cell in the lower intermediate zone. At embryonic day 16, immunoreactivity for the GABAA receptor was present within the prospective lamina 1 and the subplate, but not in the lower intermediate zone. From embryonic day 18 onwards, the immunostaining for the GABAA receptor labelled, unambiguously, the subplate as a lamina clearly separated from the suprajacent cortical plate. At embryonic day 18, the GABAA receptor started to be expressed within the lower, differentiating part of the cortical plate. Within the cortical plate, the expression of GABA in neural cell perikarya, and the immunostaining for the GABAA receptor, followed a similar spatio-temporal ("inside-out") gradient during pre- and early postnatal stages. Most GABA-positive cells of the lower intermediate zone started to disappear (or stopped the expression of GABA) by embryonic day 20, but some remained until adulthood. A similar time-course was observed for the microtubule-associated protein 2-immunoreactive cell population located at the same level.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Expression of the prodynorphin gene in the developing and adult cerebral cortex of the rat: an in situ hybridization study.

A population of cortical neurons contains the opioid peptide dynorphin; the laminar distribution of these neurons in the adult cerebral cortex and their patterns of development are not well known. We have utilized in situ hybridization techniques to localize prodynorphin mRNA-containing neurons. Rats aged from embryonic day (E) 15 through postnatal day (P) 90 were used. Prenatal animals did not show any labeling in the cerebral cortex. By P4, prodynorphin was expressed in a small number of cortical neurons for the first time. The autoradiographic signal was restricted to perikarya. In the frontoparietal cortex, labeled neurons first appeared in layer V and the upper part of layer VI. Subsequently, from P11 onward, the band expanded in an "inside-out" sequence to include layers IV through II. In the posterior cingulate cortex and in the insular and perirhinal cortices, prodinorphin mRNA containing-neurons were located preferentially in layer V. In all cortical areas analyzed, a progressive increase in the packing density of neurons expressing prodynorphin mRNA was observed until P14; it decreased slightly thereafter.

Animals↗
PubMed1988

Transient GABA-like immunoreactive axons in the corpus callosum of perinatal rats.

During the early postnatal development of the rat, gamma-aminobutyric acid (GABA)-like immunoreactive axons were contained within the subcortical white matter. Some of the immunoreactive axons crossed the midline, while others followed a vertical or longitudinal trajectory within the lateral part of the corpus callosum. Growth cones were occasionally observed. The immunoreactive axons were transitory, and were last detected at postnatal day 6.

Aging↗
PubMed1988

Synaptic endfeet in the 'acoustic nerve nucleus' of the rat. An electron microscopic study.

The medial portion of the cochlear nerve of the rat contains astrocytes, oligodendrocytes and neurons. These neurons form what has been called the 'acoustic nerve nucleus'. This nucleus has been studied here at the electron microscopic level. Its neurons are large and round, showing an eccentric nucleus, fibrillary bodies and rough endoplasmic reticulum which is not arranged in stacks. The somata and dendrites receive synaptic endfeet which can be classified into three groups according to vesicle size and shape. In general, the ultrastructural characteristics of these cells are similar to those of bushy cells as reported by other authors. The 'acoustic nerve nucleus' can be considered to be the most peripheral part of the anterior ventral cochlear nucleus.

Animals↗
PubMedDate not supplied

[Forebrain regionalization mechanisms].

Where do the regions of the forebrain come from? The paradigm that has come to light in the last ten years is that of a neural plate subdivided by soluble factors which (through the formation of gradients or of a molecular framework) transmits positional information to the neural stem cells. Some of those soluble factors are Fgf8, Sonic hedgehog and proteins of the BMP family. The neural stem cells interpret positional information in terms of the expression of combinations of certain transcription factors. Such combinations would finally be responsible for the formation of specific neural lineages (cortical, thalamic, etc.) from specific neuroepithelial regions. In addition, this primary positional information can make certain regions of the neural primordium (secondary organizers) secrete new soluble factors. These would in turn give rise to new positional information, spatially more restricted, so that the whole process would repeat itself to confer detail to a certain area. This wealth of new knowledge is already helping us to understand the cause of some brain malformations, and maybe we will soon be able to apply it to the early diagnosis and the prevention of such conditions.

Cell Lineage↗