Specific endothelial bodies in growing capillaries of the rabbit cornea

Contents of Veibel-Palade corpuscles have been studied in endotheliocytes of vessels of the rabbit eye limb (control) and in the corneal capillaries, growing after burn effect and after a combined effect of burn and colchycin. In the growing capillaries of the cornea the specific endothelial bodies are constant components of the cells and make effect to processes of the vascular new formations.     

Ultrastructural organization of the endotheliocytes of iliac lymph node capillaries in pregnancy (morphometric study)

Using light and electron microscopy and morphometry, the morphological changes in the lymph nodes of arterial and venous parts of capillaries were studied on the 11th, 17th and 21st days of pregnancy in rats. Ultrastructural changes in endothelial cells of blood vessels in the uterine lymph nodes during normal pregnancy are of adaptive nature and are possibly responsible for the relief of the blood congestion in the system of the inferior vena cava and for the improvement of the utero-placental circulation.     

Morphometric study of the ultrastructural organization of the endotheliocytes of blood capillaries in the iliac lymph nodes of pregnant rats

The ultrastructure of blood capillary endotheliocytes of iliac lymph nodes during pregnancy was investigated in rats. It was found that changes in microcirculation during pregnancy are accompanied by the appearance of the adaptive changes at all levels of lymph node structural organization. They are: increased lumen of arterial and venous part of the capillaries, increased intermediate sinus volume, increased fenestration of both parts of capillaries, a sharp increase in the number of micropinocytous vesicles and activation of transendothelial channel formation.     

Identification of digitonin binding sites on the plasma membrane of the rabbit aorta endotheliocytes

Specific reagents comprising digitonin bound to latex spheres were used as visual markers for the detection of cholesterol sites on the endothelial cell surface by scanning electron microscopy. The distribution of latex markers in the plasmolemma of the endothelial cells was investigated. These markers have strong bonds with the ligands. This interaction guarantees high specificity of binding between labeled markers and cellular membrane cholesterol.     

Increased fragility of pulmonary capillaries in newborn rabbit

The pulmonary capillaries of neonatal lungs are potentially vulnerable to stress failure because of the complex changes in the pulmonary circulation that occur at birth. We perfusion fixed the lungs from nine anesthetized newborn rabbits at capillary transmural pressures (P(tm)) of 5 +/- 5, 10 +/- 5, and 15 +/- 5 cmH(2)O. Normal microscopic appearances were seen at P(tm) values of 5 +/- 5 and 10 +/- 5 cmH(2)O, but massive airway edema was observed in lungs perfused at a P(tm) of 15 +/- 5 cmH(2)O. Consistent with this, no disruptions of the alveolar epithelium were observed at P(tm) values of 5 +/- 5 cmH(2)O, but mean values of 0.11 and 1.22 breaks/mm epithelium were found at P(tm) of 10 +/- 5 and 15 +/- 5 cmH(2)O, respectively (P < 0.05 for 5 +/- 5 vs. 15 +/- 5 cmH(2)O). These pressures are in striking contrast to those in the adult rabbit in which, by a similar procedure, a P(tm) of 52.5 cmH(2)O, is required before stress failure is consistently seen. We conclude that stress failure of pulmonary capillaries in newborn rabbit lungs can occur at P(tm) values of less than one-third of those that are required in adult lungs.     

Collagenolytic activity of rabbit V2-carcinoma growing at multiple sites.

Interaction between lanosterol and cytochrome P-450 purified from microsomes of anaerobically-grown Saccharomyces cerevisiae was studied. Lanosterol (4,4,14α-trimethyl-5α-cholesta-8,24-dien-3β-ol) stimulated the oxidation of NADPH by molecular oxygen in the presence of cytochrome P-450 and NADPH-cytochrome P-450 reductase both purified from S. cerevisiae microsomes. Lanosterol stimulated the reduction of cytochrome P-450 by NADPH with the cytochrome P-450 reductase, and induced Type I spectral change of cytochrome P-450. These observations suggest that lanosterol interacts to the substrate region of cytochrome P-450 of S. cerevisiae. Based on these facts, possible role of cytochrome P-450 in lanosterol metabolism in yeast cell is discussed.     

Ultrastructure of the capillaries of nerve tissue transplants growing in the anterior chamber of the eye

Blood capillaries have been studied electron microscopically in the areas of grafts (rat embryonal hippocamp and septal cerebral parts transplanted to mature rats) containing mainly nervous, glial or connective tissue cells. Certain differences in the capillary wall structure have been revealed. In areas with a great concentration of nervous cells, the blood capillaries are characterized by a dense arrangement of cellular elements in their walls, a continuous layer of the glial end-feet, this is specific for the CNS capillaries providing the blood--brain barrier. In peripheral area of the grafts, where glial elements predominate, the capillaries have loose arrangement of the mural cellular elements, great endotheliocyte activity, thick connective tissue tunic, lack of a dense glial surrounding. These characteristics make dubious the statement whether these capillaries possess the blood--brain barrier function. In places where connective tissue cells make aggregates, the capillaries do not possess the barrier properties because of perforations and fenestrae in endothelium and interruptions of the basal membrane, absence of pericapillary glial elements. All types of the capillaries demonstrate certain signs of a high functional activity. Formation of the capillary structure depends on the surrounding tissue.     

Automated scanning of bone marrow cell colonies growing in agar-containing glass capillaries

An optical scanning system was developed to determine the growth of clusters and colonies of granulocytes and macrophages from mouse bone marrow cells in agar capillary tubes. The system consists of a commercially available photometer with a densitometer attachment, a two-mirror set to receive the light scattered by the cell colonies, a multiple capillary holder and an automatic sample changer. Parameters affecting scanning were examined and optimized: background scatter, instrument adjustments (e.g. signal damping) and threshold settings for clusters and colonies. Combined with the advantageous agar capillary technique, the complete scanning system provides an easy, accurate and sensitive method for rapid quantitation of hemopoietic cell colony formation in vitro.     

Proliferative activity in endometrial hyperplasia and adenocarcinoma

Studies on the proliferative activity of cells in endometrial hyperplasia and adenocarcinoma were performed using techniques detecting Proliferating Cell Nuclear Antigen (PCNA) and Nucleolar Organizer Regions (NORs). PCNA expression was defined as the percentage of nuclei showing reactivity in 200 cells per sample. The mean AgNOR count per cell was calculated following the analysis of at least 100 nuclei per sample at a magnification of x 400. Student-t test was used for the statistical analysis. The results obtained indicate that the evaluation of cell proliferative activity expressed by AgNOR count and PCNA index can help in the distinction between atypical hyperplasia and well-differentiated adenocarcinoma, and thus can serve as a useful pathological criterion.     

Evaluation of cranial bone suture autotransplants in the growing rabbit

A coronal bone suture segment was autotransplanted into an experimentally created defect in the nongrowing portion of the nasal bone in 12 5-week-old male New Zealand white rabbits. The animals were sacrificed 90 days postoperatively. In most specimens the transplants were well incorporated into the recipient site. The transplanted sutures appeared narrower radiographically, and the bony projections of the sutures were not as long as those seen in control sutures. In each case the transplanted sutural ligament had atrophied, and six of the transplants showed bony union across the sutural space. The results suggest that growth and biomechanical stresses are important for maintenance of the sutural ligament and for the stimulation of bone deposition.     

Morphometric data on the lymph capillaries of the ventricles of the rabbit heart

A morphometric analysis was done on the lymph capillaries of both left and right ventricles from the rabbit heart. The measurements were made on the lymphatics identified in the subepicardium, myocardium and subendocardium of the ventricular walls. Quantitative evaluations were carried out on light and electron microscopic sections by a computerized image analysis system. The following parameters were selected and measured: (1) the diameter (of area-equivalent circle) of lymph capillaries, (2) the diameter of the uncoated micropinocytotic vesicles (located on the abluminal and adluminal side and in the cytoplasm of the endothelial cell) and the area occupied by the vesicles per unit area of cytoplasm. Differences in the size of the lymph capillaries were found in the three layers (subepicardium, myocardium and subendocardium) of the ventricular walls. The largest vessels were present in the subepicardium both in the left ventricle and in the right one. No significant variations were found in the lymphatics of corresponding regions on both ventricles. Little variations on the mean diameter of the uncoated micropinocytotic vesicles are present in the three regions of the endothelial wall. In the left ventricle only, the subendocardial vesicles are significantly larger than the subepicardial and the myocardial ones (p less than 0.05). The areal density occupied by vesicular system in the three layers of the ventricular wall showed significant differences in both ventricles (p less than 0.05). The vesicles present in the subepicardial vessels occupied the smallest areal density. No significant variations existed in the vesicular areal density between the two ventricles.(ABSTRACT TRUNCATED AT 250 WORDS)     

Distribution and origin of acetylcholinesterase activity in the capillaries of the brain

Summary Areas containing AChE-positive capillaries were mapped in the brain of the cat and the guinea pig. Regions with AChE-positive capillaries mostly also contain neuronal elements with AChE activity. Electron-microscopical cytochemistry revealed localization of AChE in basement membranes of endothelial cells and pericytes very often in continuity with activity of the extracellular space. Intraendothelial AChE activity was seen only in pinocytic vesicles. The vascular AChE is thought to be of neuronal origin since no cytochemical evidence has been obtained for a synthesis of this enzyme in endothelial or other non-neuronal cells in the CNS.Drs. H. Kaiya and L. Toth were recipients of research fellowships granted by the Max Planck Society     

Proliferative activity of gastric and duodenal endocrine cells in the rat

The replicative activity and migration of gastrin, somatostatin and serotonin cells in rat stomach and duodenum was studied using combined immunocytochemistry and autoradiography after 3H thymidine pulse-labeling. Our results show that a small proportion of gastrin, somatostatin and serotonin immunoreactive cells displays proliferative activity. The overall labeling index ranged from 1.3% for gastric endocrine cells to 3.2% for duodenal endocrine cells. In a pulse chase experiment, labeling indices of immunoreactive cells were estimated at several time intervals after 3H thymidine administration. Significant differences in labeling index were not found. Migration of 3H thymidine labeled endocrine cells towards the luminal surface was not found in the stomach nor in the duodenum. It is concluded that 1) these endocrine cells have replicating activity; 2) the replicative activity of endocrine cells is higher in the duodenum than in the stomach; 3) the various cell types do not show significant differences in replicating activity and 4) endocrine cells did not seem to migrate to the luminal surface of the mucosa along with the other epithelial cells.     

Proliferative activity of gastric and duodenal endocrine cells in the rat

Summary The replicative activity and migration of gastrin, somatostatin and serotonin cells in rat stomach and doudenum was studied using combined immunocytochemistry and autoradiography after ³H thymidine pulse-labeling. Our results show that a small proportion of gastrin, somatostatin and serotonin immunoreactive cells displays proliferative activity. The overall labeling index ranged from 1.3% for gastric endocrine cells to 3.2% for duodenal endocrine cells.In a pulse chase experiment, labeling indices of immunoreactive cells were estimated at several time intervals after ³H thymidine administration. Significant differences in labeling index were not found. Migration of ³H thymidine labeled endocrine cells towards the luminal surface was not found in the stomach nor in the doudenum.It is concluded that 1) these endocrine cells have replicating activity; 2) the replicative activity of endocrine cells is higher in the duodenum than in the stomach; 3) the various cell types do not show significant differences in replicating activity and 4) endocrine cells did not seem to migrate to the luminal surface of the mucosa along with the other epithelial cells.     

Ultrastructural cytochemistry of the nucleus and nucleolus in growing rabbit oocytes

Summary— Ultrastructural changes of the germinal vesicle during the growth of rabbit oocytes were studied by means of light and electron microscopy, ³H-uridine autoradiography, Ag-NOR staining and E-PTA staining. Particular interest was paid to the nucleologenesis and condensation of chromatin. In contrast to other mammalian species, chromosome condensation in rabbit oocytes occurred concomitantly with rRNA synthesis-dependent nucleolar compaction and preceded nuclear envelope breakdown and resumption of meiosis.