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Biomedical subjects

L Luciano

Publications and source records attributed to L Luciano.

At least 91 records · Page 5Linked to original sources
PubMed1979

A new morphological aspect of the brush cells of the mouse gallbladder epithelium.

The brush cells of the gallbladder epithelium of the mouse have microvilli not only at their luminal border but also on their lateral surface, from the level of the nucleus to the junctional complex. The lateral microvilli radiate from the brush cell in all directions, contain a core of filaments, and penetrate up to 3 mum into the adjacent cells. The microvilli in these locations display small desmosomes at their base.

Animals↗
PubMed1979

[The structure of the gastric mucosa of the llamas (Lama guanocoe and Lama lamae). I. Forestomach].

The mucous membrane of the first and second compartments (ventral regions) as well as of the third compartment of Lama guanacoe and Lama lamae stomach shows tubular glands opening into pits. Below the surface epithelium blood capillaries of the fenestrated type form a regular network, each mesh of which surrounds a gastric pit. From a morphological point of view (thin section and freeze-fracture replicas) the columnar cells of the surface epithelium and those of the pits closest to the capillaries are largely similar to the epithelial cells of the rabbit gallbladder. This similarity suggests that at the level of the columnar cells sodium-dependent water reabsorption occurs. This reabsorption has already been demonstrated in the abovementioned compartments by physiological methods. The surface and foveolae epithelial cells as well as some cells of the tubular glands have a secretory function. Their secretory granules contain mucosubstances, as indicated by light-(PAS- and Alcian blue reactions) and electron microscopic (PA-TCH-Ag-reaction) histochemistry. The secretory granules originate from the Golgi complex which shows a positive histochemical reaction in its innermost sacculi at the electron microscope level. Endocrine cells (s. second part of this investigation) are rare. The mucosal membrane of each muscular lip separating the glandular sacs in the first compartment shows a stratified, not keratinized, squamous epithelium.

Absorption↗
PubMed1979

Morphological and functional aspects of the glomerular basement membrane.

Addition of Alcian Blue to the fixative reveals structural elements bearing negatively charged sites within the glomerular capillary wall of the rat kidney. According to previous research (review by Brenner et al., 1977), these charges represent one of the most important functional components of the glomerular filtration barrier. Alcian Blue also demonstrates negatively charged microfibrils (probably glycoproteins) of the mesangial matrix. Preliminary observations of glomeruli of lower vertebrates suggest that there is always a close correlation between the presence of microfibrils and mesangial cells.

Alcian Blue↗
PubMed1978

Communicating junctions of the human sensory retina. A freeze-fracture study.

Using the freeze-fracture technique communicating junctions could be identified between the cells of the adult human sensory retina. Communicating junctions with particles arranged in linear or circular rows as well as in small aggregates were found between adjacent photoreceptor endings. Communicating junctions with particles forming plaques were localized in the inner plexiform layer. They were isolated between unidentified cell processes or lay close to active sites of chemical synapses, thus suggesting the occurrence of "mixed" (chemical and electrical) synapses in this layer. Furthermore, communicating junctions were detected between portions of Müller's cells.

Cell Communication↗
PubMed1978

[Study on the effect of formaldehyde on the immunological reactivity and morphology of hepatitis B-antigen (author's transl)].

Treatment of purified HB-antigen with formaldehyde solution changes its immunological reactivity and its morphology. A decrease in antigen activity by formaldehyde treatment could be demonstrated by radial immunodiffusion and by radioimmunoassay (Fig. 1). Electron microscopic studies revealed a segmentation of tubular HBAg particles into small round forms (Fig. 3) and a shift of the ratio tubular forms: spherical forms in favour of the spherical particles (Table 1). These findings support the hypothesis that 20 nm particles originate from a division of tubular forms. Round forms became smaller after formaldehyde treatment (Fig. 4). The treatment with formaldehyde changed neither the density of HBsAg testes in CsCl gradients, nor the immunologic identity tested in immunodiffusion tests (Fig. 2). All prescribed effects were observed only in the high concentrations of formalin (10 and 1%), whereas in the concentration of 0.1%, which is usually used for inactivations in the development of vaccines, no immunological and morphological changes of the HBAg could be seen.

Densitometry↗
PubMed1977

Electron-microscopic histochemistry of the most peripheral retinal vessels.

The reaction of Thiéry (periodic acid-thiocarbohydrazide-silver proteinate) has been applied for histochemical analysis of the structures composing the halo of the most peripheral human retinal vessels. It is suggested that glycoproteins lie in the ground substance of the halo as well as well as in the basement membranes of endothelial cells, pericytes, and Müller cells. Glycogen particles were found in endothelial cells, in pericytes and especially in Müller cells.

Basement Membrane↗
PubMed1976

Lysosomes in normal and degenerating neuroblasts of the chick embryo spinal ganglia. A cytochemical and quantitative study by electron microscopy.

Lysosomes were studied by both cytochemical and quantitative methods in normal and degenerating neuroblasts of the chick embryo spinal ganglia. In normal neuroblasts (primitive and intermediate neuroblasts) both primary lysosomes and autophagic vacuoles were found; these organelles were usually located in the region containing the Golgi complex. In degenerating neuroblasts lysosomes appeared sharply decreased in number with respect to normal neuroblasts. Moreover, lysosomes were always evident as intact organelles surrounded by a membrane and the acid phosphatase activity appeared localized exclusively within these bodies. A diffuse distribution of acid phosphatase activity was only found in a limited number of cases during the terminal stage of the process. Possibly in these cases the enzymatic activity depended on the cells which enveloped the degenerated neuroblast remnants. The present results indicate that lysosomes do not play a primary role in the degenerative process studied.

Acid Phosphatase↗
PubMed1976

Freeze-fracture aspects of the perineurium of spinal ganglia.

The internal portion of the capsule of the spinal ganglia of rabbit is composed of continuous superimposed layers of flattended cells (perineurium). In replicas, extensive meshworks of strands, presumably forming zonulae occludentes, are found between the perineurial cells of the same layer. Adjacent layers are joint by maculae occludentes located on the lateral processes of the perineurial cells. Occasionally small gap junctions lie within the meshes of the zonulae occludentes.

Animals↗
PubMed1975

Zonulae occludentes of the myelin lamellae in the nerve fibre layer of the retina and in the optic nerve of the rabbit: a demonstration by the freeze-fracture method.

Ridges and grooves composing extensive zonulae occludentes are revealed by the freeze-fracture method on split myelin lamellae in the nerve fibre layer of the retina and in the optic nerve of the rabbit. The junctions are located immediately internal to the outer loop of the myelin sheath and in corresponding areas of deeper myelin layers. They follow a straight or gently undulating course along the axis of the fibres. Only at the paranodal region of nodes of Ranvier do they deviate and assume a transverse course, The strands of these zonulae occludentes probably represent the radial thickenings of the intraperiod line described in thin sections.

Animals↗
PubMed1975

Freeze-fracture faces of the perineurial sheath of the rabbit sciatic nerve.

Replicas of the perineurium of rabbit sciatic nerve fascicles show extensive zonulae occludentes between the flattened cells of each perineuriallamella. The junctions formed by the zonulae occludentes are of the morphologically 'tight' type. Therefore, theyare likely to represent the anatomical site of the diffusion barrier previously demonstrated by other morphological and physiological methods. Neighbouring perineurial lamellae are connected to one another by numerous maculae occludentes, some of which lie on thelateral processes of the perineurial cells. Within the meshes of the maculae occludentes and close tothem, small gap junctions can be observed.

Animals↗
PubMed1975

[Fine structure of venules and lymphatics of the dog thyroid gland].

The endothelial cells of the venules (collecting venules) of the thyroid gland of the dog are very thin and show fenestrations. In their wall, however, more 'primitive' smooth muscle cell layers are recognizable. The endothelial cells in the lymphatic vessels are also thin, but continuous. They have all known morphological characteristics of these vessels. The fenestrae of the venules' endothelium could facilitate hormone passage from the interstitial tissue into the blood stream.

Animals↗