Histology and histopathology Vol. 8, nº 2 (1993)
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- PublicationOpen AccessFine structure of the retinal photoreceptors of the tiger salamander (Ambystoma tigrinum)(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 1993) Braekevelt, C. R.The retinal photoreceptors of the tiger salamander (Ambystoma tigrinum) have been studied by light and electron microscopy in both light- and dark-adaptation. Rods and cones are present in this duplex retina in a ratio of about 20:1. As in other urodele species these photoreceptors are very large cells. The rod outer segment is composed of bi-membranous discs of uniform diameter displaying several very deep incisures. The rod inner segment displays an ellipsoid of mitochondria and a myoid region which changes in diameter during the lighting cycle indicating that rods undergo photomechanical movements. Rod nuclei are located at all levels of the outer nuclear layer and rod spherules are large and display several invaginated and superficial synaptic sites. Cone photoreceptors while large cells are smaller than the rods. They show a smaller tapering outer segment, a large distal ellipsoid of mitochondria and a prominent paraboloid of glycogen but no oil droplet within the inner segment. Judging by the width of the myoid region which remains similar throughout the lighting cycle, cones in this species show no retino-motor responses. Cone nuclei are less electron dense than rods and are also located at all levels of the outer nuclear layer. The cone synaptic pedicle is larger than that of the rods and also shows several invaginated and superficial synaptic sites.
- PublicationOpen AccessPathological changes in organs of rats chronically exposed to hypoxia. Development of pulmonary lipidosis(Murcia : F. Hernández, 1993) Wolman, M.; Cervós-Navarro, J.; Sampaolo, S.; Cardesa, AntonioRats were exposed to chronic normobaric hypoxia of progressively increasing severity; down to 8% or 7% oxygen concentrations. In addition to loss of weight, pathology revealed congestion, haemorrhages, hypertrophy of the heart involving mainly the right ventricle, thickening of arteries, ischaemic changes in the myocardium and extrarnedullary haematopoiesis in the spleen. Changes not described up until now were: 1) sheets of foam cells in the pulmonary alveoli; 2) foamy and solid storing cells in the spleen; 3) mucoid changes in the atrioventricular valve leaflets; 4) hyperplasia of the juxtaglomerular apparatus; 5) atrophy of the adrenal glomerulosa and hyperplasia of medulla; 6) atrophy of the perifollicular B-cell zone in the spleen; and 7) lipid pigment deposition in various organs. The findings indicate that severe chronic hypoxia induces a significant pulmonary lipidosis similar to that caused by amphiphilic cationic drugs, presumably by inhibiting hydrolytic enzyme activities. The observations are of importante in human hypoxic conditions and open the possibility of their rational treatment.
- PublicationOpen AccessPinocytotic vacuoles in human dental pulp capillaries(Murcia : F. Hernández, 1993) Lyroudia, K.I.; Economou, L.; Manthos, A.; Zervas, P.; Albanou, A.; Foroglou, Ch.Dental pulp capillaries were studied in human. They were of the cantinuous type, with the exception of a small number which were of the fenestrated type, located in the vicinity of the odontoblasts. A characteristic morphological peculiarity was found in the endothelial cells. In places there was a large quantity of multisized vacuoles. The vacuoles were evidently of pinocytotic origin, and their content was emptied into the extracapillary space. The initiation of their formation was indicated by the creation of cytoplasmic flaps, which could not be characterised as typical pseudopodia, and which in cross sections resembled microvilli. The flaps engulfed a quantity of plasma and then, after bending over, their edge fused with the cell, creating a vacuole. The vacuole, after being moved abluminally, was emptied into the pericapillary area by exocytosis. There was indication that flaps created at the borders of the endothelial cells (flanges) acted likewise, transporting vacuoles through the intercellular spaces. Micropinocytosis, was a distinctly different phenomenon, contributing, to a very small degree, to the intracellular enlargement of the vacuoles. It seems that this vacuolar mechanism of transportation serves an augmented metabolic need of the surrounding tissue.
- PublicationOpen AccessCellular proliferation andlor differentiation can condition modifications in the expression of AgNORs in rat anterior pituitary cells during growth(Murcia : F. Hernández, 1993) Carbajo, S.; Carvajal, J.C.; Rodríguez, J.; Carbajo-Pérez, E.The expression of argyrophilic nucleolar organizer regions (AgNORs) was studied in the anterior lobe of the hypophysis of 1-, 7-, 14-, 28- and 80-day-old rats. Mean area and numbers of AgNORs per nucleus decreased during this period with a simultaneous increase of both nuclear area and mean AgNOR-particle area. Comparison of our data on AgNOR expression with previously reported data on the proliferative activity and cell maturation and differentiation of anterior pituitary cells during a similar period led us to conclude that, at least in our experimental model, variations in the expression of AgNORs are more related to phenomena of cellular maturation than to proliferative activity.
- PublicationOpen AccessGastric intestinal metaplasia eleven years after randomized selective proximal vagotomy for peptic ulcer(Murcia : F. Hernández, 1993) Rubio, C.A.; Emas, S.; Slezak, P.; Nakano, H.; Kalin, B.The presence of intestinal metaplasia (IM) 11 years after selective proximal vagotomy (SPV), selective proximal vagotomy with pyloroplasty (SPV + PP) and selective vagotomy with pyloroplasty (SV + PP) was investigated in 38 consecutive patients. IM was significantly more frequent in SPV than in SV + PP, SPV + PP or in unoperated controls of matching ages. IM occurred more frequently both at an older age (260 years) in SPV and in a larger number of gastric areas than in the other group of patients. Reports in the literature indicate that vagotomy may increase the risk of gastric carcinoma and that IM inay antedate malignant transformation. It would thus appear that patients previously operated with SPV (without pyloroplasty) having IM, should be the group of patients to be enrolled in endocospical surveillance programs for detection of possible cancer development.