Showing papers by "Laura López-Mascaraque published in 1989"

Connections of the olfactory bulb and nucleus olfactorius anterior in the hedgehog (Erinaceus europaeus) : fluorescent tracers and HRP study

Abstract: The projections of the main olfactory bulbs (MOBs) and the dorsal part of the anterior olfactory nucleus (NOA) in the hedgehog (Erinaceus europaeus) have been studied by fluorescent tracers and the horseradish peroxidase method (HRP), respectively, to reveal the pattern of labeling from these structures. After different dye injections in both MOBs, labeled cells were present in the following structures: tenia tecta, vertical limb of the diagonal band of Broca, and medial septal nucleus in the ipsilateral injection site; and the NOA, piriform cortex, nucleus of the lateral olfactory tract, horizontal limb of the diagonal band of Broca, posterolateral cortical amygdaloid nucleus, anterior amygdaloid area, and dorsal raphe nucleus in both hemispheres. Structures showing double-labeled cells were the NOA, horizontal limb of the diagonal band of Broca, nucleus of the lateral olfactory tract, anterior amygdaloid area, and posterolateral cortical amygdaloid nucleus. After HRP injections in the dorsal part of the NOA, labeled cells were distributed in the NOA, nucleus of the lateral olfactory tract, posterolateral cortical amygdaloid nucleus, piriform cortex, horizontal and vertical limbs of the diagonal band of Broca, mitral cell layer of the MOB, tenia tecta, anterior amygdaloid area, and the contralateral NOA. We suggest that the contralateral projection nuclei to the MOB of the hedgehog, unusual in other mammals, and the large number of cells with axonal collaterals projecting to both hemispheres, may be a strategy in these animals to bilaterally integrate brain functions at the expense of its reduced corpus callosum.

Structure of the nucleus olfactorius anterior of the hedgehog (Erinaceus europaeus).

Abstract: The cytoarchitecture, topography, and cellular structure of the nucleus olfactorius anterior (NOA) in the hedgehog have been studied in Nissl-stained and Golgi preparations. The NOA is an important receptive allocortical formation for olfactory fibers and the major source of association fibers relating the main olfactory bulb with the rest of the olfactory brain. It was divided into a bulbar part; four subdivisions named lateral, dorsal, medial, and ventral; an external part; and a posterior part. Except for the external and posterior subdivisions, the NOA is relatively homogeneous and, in spite of the apparent lack of sublamination in Niss-stained material, four clearly defined cellular laminae were distinguished by the Golgi method. These layers were found to be strikingly similar to those in the piriform cortex. Layer I contains the terminal ramifications of apical dendrites of pyramidal cells and the collaterals of the lateral olfactory tract. The superficial part of layer II contains extraverted pyramidal cells with two or three apical dendrites ramifying in layer I. Most pyramidal cells in the deep part of layer II and layer III are typical pyramidal cells with axons entering the commissura anterior. Some pyramidal cell axons bifurcate into two branches running in opposite directions in the commissura anterior. The interstitial zone below layer III contains deep pyramidal cells and polymorphic cells with ascending branches. Cells with intrinsic axons were classified into four main categories according to the distribution of their axonal ramifications: 1) cells with very restricted axons, 2) cells with axons oriented tangentially in the superficial part of layer II, 3) cells with ascending axons located in the deep part, and 4) chandelierlike cells. Finally, some functional considerations are discussed.

Layers I and VI of the visual cortex in the rabbit. A correlated Golgi and immunocytochemical study of somatostatin and vasoactive intestinal peptide containing neurons.

Abstract: Immunocytochemical and Golgi staining techniques were used to correlate the morphology of neurons in layers I and VI of the rabbit's visual cortex. Antisera against somatostatine (SOM) and vasoactive intestinal peptide (VIP) were employed in the immunocytochemical investigation. In layer I, SOM-positive cells were multipolar and situated in the lower part of the layer. Some had long horizontal axons like those of the Cajal-Retzius cells when observed by the Golgi method. Most VIP-positive cells were bipolar and some had axons throughout this layer. In layer VI, SOM-positive cells were of multipolar, bitufted, or pyramidal-like morphology. Frequently, they presented a thicker and more prominent dendrite with various collaterals and axons with ascending, horizontal and sometimes descending courses. Cells with recurrent axon were occasionally observed. Either the dendrite or the axonal characteristics are similar to some Golgi-impregnated non-pyramidal cells of our material, including the inverted pyramidal neurons. In this study, we have described peptidergic cells in these layers and correlate them with Golgi impregnated neurons and with those described in the literature.