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The cardiac plexus of the Wistar rat was investigated in whole-mount preparations of the atria by NADH-diaphorase staining and by the acetylcholinesterase (AChE) histochemical technique. The plexus lies over the muscular layer of the atria, dorsal to the muscle itself, in the connective tissue of the subepicardium. The plexus contains on average 975 +/- 150 neurons, occurring singly or gathered in packed ganglia. The ganglia are found regularly in certain situations, namely, cranially to the pulmonary veins (44% of total); cranially and to the left of superior vena cava (10%); in the interatrial groove (21%); to the left of the left pulmonary vein (11%); caudally to the pulmonary veins (12%) and in the wall of the coronary sinus (1%). Ganglia are never found on the auricular appendages. For the histochemical demonstration of AChE, the 'direct coloring' copper ferrocyanide method was used. Extrinsic nerves enter the atria along the superior vena cava, along the pulmonary veins and along the coronary sinus, forming ganglion-containing plexuses. From specific sites of these plexuses, nerves proceed to the ganglia located to the left of the superior vena cava, to the ventral and dorsal ventricular wall and to the wall of the right atrium, where they form a delicate plexus accompanying the muscle fibers. Most of the neurons of the plexuses displayed AChE activity in the cytoplasm though they presented different reaction intensities. The distribution of cardiac nerves from groups of neurons located at discrete sites may indicate that postganglionic nerves selectively project to and thus control specific cardiac regions and/or functions.

Based on our previous studies on the human normal venous angioarchitecture of the esophagogastric transition segment, we performed a similar analysis in 25 postmortem specimens obtained from subjects with a diagnosis of portal hypertension. The specimens were injected with India ink or barium sulfate and sectioned for histological examination. A 'weak' zone (point of lesser resistance) was described as being the most probable site of origin for the development of varicosities in the complex venous system of the esophagogastric junction. Such a system can be considered to be a physiological hemodynamic venous blockade mechanism interposed between the portal system and the systemic veins. The 'weak' zone is made up by the scarce submucous veins (shunt veins), by the submucous confluent and final confluent trunks, and by the true perforating veins of the tunica muscularis which compose a venous unity located about 3-5.5 cm above the Z (epithelioglandular) line.

The elastic, elaunin and oxytalan fibres in the tunica mucosa and tela submucosa of veins of the human lower oesophagus were studied in 30 necropsy and biopsy specimens using appropriate histological and ultrastructural methodologies. Elaunin fibres predominate in the veins endowed with muscle cells. Scattered oxytalan and elastic fibres were also observed, the latter being more numerous at the vein periphery. No noteworthy fibre arrangement was encountered in veins lacking muscle cells. Those fibres disposed around the veins were considered to belong to the connective tissue of the tunica mucosa and tela submucosa in which they are embedded. The veins of the lower oesophagus seem to be of low elasticity, which may be related to a blockage mechanism described for the gastro-oesophageal blood stream in cases of portal hypertension.

The spatial arrangement of the muscular, elastic and collagenous fibers was examined in 20 splenic veins of adult humans. Histologic and panorganographic sections were stained by the following methods: azan, resorcinfuchsin (Weigert), Verhoeff-van Gieson's stain and Masson's trichrome. Unstained sections were examined under polarized light. The results show that the muscular and collagenous fibers of the splenic vein exhibit an elongated spiral arrangement with no polarization. The elastic fibers form a threedimensional network disposed predominantly in a longitudinal direction. Hemodynamics are discussed based on the spatial structure of the muscular, elastic and collagenous elements of the vein wall and its relationship with the circulatory functions of the spleen.

An electron-microscopic study of ependymal cells in 24 different areas of the encephalic ventricular system of Bradypus tridactylus was made, with a view to making a comparative analysis, of a topographical kind, of various cell components: cilia, microvilli, plasma membrane, cytoplasmic protrusions, types of cellular junctions, ribosomes, Golgi apparatus, endoplasmic reticulum, microfilaments, microtubules, mitochondria, granules and dense bodies. There were differences in the distribution of all these cytologic elements, according to the topography, being a complement to a similar work done by the same authors with light-microscopy. By means of a morphofunctional analysis they draw the conclusion that even if one can admit the passage of substances by an intracellular route, on the other hand few facts support the idea the intracellular absorption or secretion could be considered as important phenomena in a great number of the ependymal areas studied.

With the purpose of studying the venous angioarchitecture of the esophagogastric transition segment (EGTS), 30 speciments were obtained from bodies a few hours after death. These specimens were injected with a 25% aqueous solution of india ink (drop-by-drop continuous infusion) through the left gastric vein and the splenic vein. The specimens thus prepared underwent three types of methods: (1) clarification by the Spalteholz method for a panoramic stereoscopic observation of the venous angioarchitecture; (2) thick sections in a series from 100 to 150 micrometer, stained by the Azan method, and (3) in 10-micrometer serial sections stained by the method of Masson, the perimeter of the veins having been measured in order to ascertain the venous density. The result of this investigation allows the conclusion that there are three venous nets in the muscular layer of the EGTS (perimuscular, intermuscular and submuscular). These three nets, especially the intermuscular and the perimuscular, converge at the extremities of the EGTS, most markedly in the cranial part, to large confluent trunks, going out of the organ from there through perforating trunks principally to the affluents of the portal vein. It thus constitutes a more or less independent segment under the venous point of view, depending essentially on the system of that vein. A marked predominance of perforating vasa of the false type in zone 3, especially at its intermediate part exactly at the stretch where most part of the veins of the mucous-submucous system lie at a deeper site, together with other peculiarities of venous distribution of this region, allows the morphofunctional deduction that, at this point, the muscular layer be a barrier between the deep and the peripheral venous circulation of the esophagus.

The fraction of cellular volume occupied by the cytoplasm has been assessed by point-counting volumetry in 0.5 micrometer araldite sections. Measurement of the transection radius of the nuclei of acinar cells allowed the assessment of the mean nuclear volume according to the method of Bach. With these data, the cytoplasm volume was calculated in cubic micrometers. Ultrastructural morphometric data were obtained by means of superimposing on the electron photomicrographies (x 21,000 or x 28,500) a test system of 84 evenly spaced segments according to Weibel et al. The analysis of the values obtained for the pancreas and parotid gland allowed for the supposition that the process of maturation in the rat, either for the pancreas or the parotid gland, occurs simultaneously with the mitotic process, this last being held as the predominating one in the first 3--4 postnatal weeks. The cytodifferentiation process becomes more marked in the last phases studied and on the 40th day it already shows parameters held as similar to those of the adult animal.

The electromyographic study of the subclavius muscle (SM) was performed in 31 different movements, in 12 subjects (10 male and 2 female) aged from 17 to 28 years. The action potentials were obtained with an electromyograph Teca TE 4. Our findings suggest that the SM acts mainly on the stability of the sternoclavicular joint; with more or less intensity according to the degree of the clavicular interaction with the movements of the peripheral parts of the superior limb. The SM seems to act as a substitute for the ligaments of the sternoclavicular joint.

Histological and histochemical aspects of the whole encephalic ventricular system of eight specimens of Bradypus tridactylus were studied. After anesthesia and perfusion, the encephalons were obtained by craniotomy. Transverse serial sections of the encephalon, stained according to Azan (Heidenhain's method) or Kluver-Barrera for nerve cells and myelinated nerve fibers; silver impregnation was carried out according to Cajal-De Castro's or Palmgren's methods. The following histochemical reactions were used: PAS (McManus), metachromasia, acid phosphatase (Gomori), Brachet's and Gomori's trichromic reaction (modified by Bargmann for neurosecretion). Histologically, different characteristics of the ependymal cells in different areas were observed, which would be related to functional peculiarities of each area of the encephalic ventricles. The ependymal cells showed discrete apical basophilia due to the presence of RNA which disappears after treatment with crystalline ribonuclease. The PAS reaction indicated the presence of a small quantity of PAS-positive substances in the apical zone of the ependymal cells and the subependymal tissue. These substances disappeared after the salivary amylase test, indicating the presence of glycogen. The acid phosphatase reaction was negative.

A comparative analysis of the measurements of the distances between the small saphenous vein and the common peroneal and tibial nerves at the back of the knee was performed in melanodermal and leukodermal male adults. The positions in which the vein lies ore closely to the nerves are stressed and should be considered as critical in possible surgical damage to the nerves during saphenectomy.