PubMed Health⌕ Search

Biomedical subjects

F Valverde

Publications and source records attributed to F Valverde.

At least 73 records · Page 4Linked to original sources
PubMed1987

Chandelier cells in the auditory cortex of monkey and man: a Golgi study.

Using the Golgi method we studied chandelier cells in the auditory cortex of monkeys (Macaca irus) subjected to hypoxia before perfusion, and in newborn humans deceased in hypoxic states. In humans these cells have round or ovoid bodies showing usually beaded and sparsely-spined dendrites. These may arise either from both apical and basal poles or from all directions of the soma. With respect to their axons, we found two different types of chandelier cells: cells with extended chandelier complexes which occupied several cortical layers, and cells with local chandelier complexes. The former has rows of vertical terminal endings and the latter has vertical terminals and curved beaded fibers. In adult monkeys, chandelier cells show similar characteristics. The possible relationships between chandelier cells, hypoxia and epilepsy, is discussed.

Adolescent↗
PubMed1987

Transitory population of cells in the temporal cortex of kittens.

A correlated study, using conventional electron microscopy and the Golgi method in the subplate layer and lower part of layer VI, in the developing temporal cortex of kittens has been made. Neuronal death was identified in semithin sections and with the electron microscope. The existence of presumptive degenerating cells in Golgi preparations has been suggested. This transitory population of early-generated subplate cells might be involved in the organization of cortical afferents before the final targets have completed their migrations.

Animals↗
PubMed1986

Structure of the olfactory bulb of the hedgehog (Erinaceus europaeus): description of cell types in the granular layer.

The cytoarchitecture of the olfactory bulb and the cell types in the granular layer of adult hedgehogs have been studied with the Golgi method. The mitral cell layer does not stand out as a monolayer as in most mammals; it is arranged as a diffuse stratum with mitral cells displaced into the external plexiform layer. The external plexiform layer is exceedingly thick and contains the branches of peripheral processes of granule cells and displaced mitral and tufted cells. The granular layer contains granule cells and varieties of short-axon cells. Among granule cells a type of cell with an elaborate system of protrusions close to the cell body has been found. Four main varieties of short-axon cells are described. These include cells with local or extended axons, according to the branching pattern of their axons inside the granular layer or extending into the external plexiform layer as well. Short-axon cells were also classified as cells with smooth and spinous dendrites. A variety of cell with smooth dendrites and elaborate axonal system reaching the periglomerular zone is described. This type of cell has been found frequently in the olfactory bulb of the hedgehog. In comparison to several other mammals, short-axon cells in the olfactory bulb of the hedgehog have been found to be particularly abundant and to have more complex axonal systems. It is suggested that some of them may represent inhibitory interneurons acting upon granule and periglomerular cells, playing an important role in the centrifugal pathway controlling the olfactory input.

Animals↗
PubMed1986

Neocortical layers I and II of the hedgehog (Erinaceus europaeus). I. Intrinsic organization.

The intrinsic organization and interlaminar connections in neocortical layers I and II have been studied in adult hedgehogs (Erinaceus europaeus) using the Golgi method. Layer I contains a dense plexus of horizontal fibers, the terminal dendritic bouquets of pyramidal cells of layer II and of underlying layers, and varieties of intrinsic neurons. Four main types of cells were found in layer I. Small horizontal cells represent most probably persisting foetal horizontal cells described for other mammals. Large horizontal cells, tufted cells, and spinous horizontal cells were also found in this layer. Layer II contains primitive pyramidal cells representing the most outstanding feature of the neocortex of the hedgehog. Most pyramidal cells in layer II have two, three or more apical dendrites, richly covered by spines predominating over the basal dendrites. These cells resemble pyramidal cells found in the piriform cortex, hippocampus and other olfactory areas. It is suggested that the presence of these neurons reflects the retention of a primitive character in neocortical evolution. Cells with intrinsic axons were found among pyramidal cells in layer II. These have smooth dendrites penetrating layer I and local axons forming extremely complex terminal arborizations around the bodies and proximal dendritic portions of pyramidal cells. They most probably effect numerous axo-somatic contacts resembling basket cells. The similarity of some axonal terminals with the chandelier type of axonal arborization is discussed. Other varieties of cells located in deep cortical layers and having ascending axons for layers I and II were also studied. It is concluded that the two first neocortical layers represent a level of important integration in this primitive mammal.

Animals↗
PubMed1986

Neocortical layers I and II of the hedgehog (Erinaceus europaeus). II. Thalamo-cortical connections.

This study examines the thalamo-cortical projections to the most superficial neocortical layers in the hedgehog (Erinaceus europaeus) after small injections of horseradish peroxidase and horseradish peroxidase conjugated to wheat germ agglutinin in the somato-sensory cortex. The injections were limited to layers I, II and upper parts of layer III/IV. Retrogradely labeled cells were plotted in serial sections through the thalamus. Injections in the somato-sensory cortex gave a pattern of elongated columns of labeled cells, extending rostro-caudally in the nucleus ventralis thalami. In the neocortex, labeled fibers extended for considerable distances running horizontally in layer I. Complementary observations demonstrate the thalamic origin of certain, coarse ascending bundles observed previously in Golgi preparations of the hedgehog. It is concluded that a major cortical input to layer I originates in the hedgehog in the principal thalamic (relay) nuclei. After injections in the somato-sensory cortex, retrogradely labeled cells were also found in the nucleus ventro-medialis thalami and very few in a zone medial to the nucleus ventralis thalami corresponding to the intralaminar thalamic nuclei. The contributions of this latter system seem to be limited in comparison with other mammals.

Animals↗
PubMed1986

[Hepatic lesions caused by alpha 1-antitrypsin deficiency in childhood. Review of 14 cases].

Fourteen cases of alpha-1-antitrypsin deficiency are presented. All of them had a PIZZ phenotype except two in which a PIMZ phenotype was found. It must be pointed out that histological findings show a great variability among the different patients most of which did not have intracellular PAS-positive amylase inclusions in liver biopsy specimens. Clinical course did not correlate with either the age of onset of the disease or the phenotype found, thus indicating that other additional factors are involved in determining prognosis. We insist on the importance of a careful study of all neonatal hepatitis syndromes in order to rule out a alpha-1-antitrypsin deficiency.

Biopsy↗
PubMed1985

Development, morphology and topography of chandelier cells in the auditory cortex of the cat.

Using the Golgi method we have studied the development, morphology and topographic distribution of chandelier cells in the auditory cortex of the cat. Kittens from 9 to 42 days old were used. Chandelier cells can be recognized in 9-day-old kittens as a distinct neuronal variety. In the 15- and 23-day-old kittens chandelier cells develop axonal complexes elongated vertically. In the 42-day-old kitten, they seem to have attained their adult morphology. They are not distributed uniformly and their predominance in certain areas suggest that they may have a relation with callosal projecting pyramidal cells.

Animals↗
PubMed1983

Haemoglobin LeporeBaltimore in a Spanish family.

Description of the clinical, haematological and biochemical aspects of a new family with heterozygous haemoglobin LeporeBaltimore. Of the 6 members affected. 4 were totally asymptomatic. All of them showed morphologic features of heterozygous beta-thalassaemia. The levels of haemoglobin Lepore ranged from 12.2 to 15% (mean value: 13.7 +/- 1.1%). The analysis of the primary structure of the haemoglobin shows that crossing over takes place between amino acid 50 of the delta-chain and amino acid 86 of the beta-chain. This is the third family, to our knowledge, with haemoglobin LeporeBaltimore so far described.

Adolescent↗
PubMed1980

A specialized type of neuron in the visual cortex of cat: a Golgi and electron microscope study of chandelier cells.

The axonal arborization of chandelier cells is characterized by its conspicuous, vertically oriented, bouton aggregates. The efferent synaptic relationships established by these terminal formations were investigated by electron microscopy of Golgi preparations after gold toning and deimpregnation. In all cases examined from layers II and III of cat areas 17 and 18, the terminal formations, here denominated specific terminal portions (stp), make symmetric synapses upon axon initial segments of pyramidal neurons. Some identified stp's were reconstructed from ultrathin serial sections with the aid of a microcomputer-based system, and the number of synaptic contacts established on axon initial segments was evaluated. No evidence was found that parts of the axonal tree other than stp's also engage in synaptic contacts. Specific terminal portions are rather variable in complexity. However, the synaptic contacts they engage in are constant and the complexity of stp's from the same axonal arborization varies. It is, therefore, clear that all stp's are terminal axonal formations of a unique, specialized type of neuron. Computer techniques and conventional Golgi observations were used to study further details of chandelier cell morphology. Axonal plexuses are preferentially, although not exclusively, local and distribute within spheric, ovoid, or disk-shaped spaces. In most chandelier cells, the main axonal trunk descends to the white matter, where we have been unable to follow it further.

Animals↗