Search

The lymphatic system of 40 specimens of Dasypus novemcinctus and 5 of Dasypus sexcinctus, both found in Brazil, were injected with Prussian blue suspension, neoprene latex (followed by partial corrosion). Lymphangioradiographic study was also made. The data concern the lymph nodes, the lymphatic networks, vessels and main trunks. The main features are the following: a few lymph nodes were missing (popliteal, subpubic and ischial); the superficial jugular ll.nn. predominate on the deep ones; the dorsal mediastinal ll.nn. are well developed; a mesentericocolic plexus is formed by the many anastomoses among the mesenteric and cecocolic ll.nn.; at regular intervals there is a concentration of vessels in the submucous network of the small intestine; the submucous network of the colon shows parallel lamellar lymphatic vessels; the mucous-submucous networks are usually independent from the subserous-muscular ones; there are two types of lymphatic networks alternating along the duodenum; folliculi lymphatici aggregati are absent; the lymphatic vessels run in the mesentery independently from the blood vessels; the mesenteric lymphatic vessels present many valves; the vessels from the diaphragm terminate directly in the cisterna chyli; there is a multipolarity of the abdominal lymphatic circulation, i.e., each organ has its own lymphatic tr.

Ventricular myocardium from several adult specimens of hummingbirds (Eupetomena macroura macroura) were subjected to study by electrocardiography and by light and electron microscopy under normal and experimental conditions as provided by injection of 2,4-dinitrophenol (DNP) and ether anesthesia. The birds were captured in Brazil, and were studied because of their high heart rates 428/460 minute on the average, seeking correlations of structure and function under normal conditions as well as after pharmacological stimuli. Under normal conditions, the hummingbird showed a highly developed sarcoplasmic reticulum, many gigantic mitochondrial with numerous tightly packed parallel mitochondrial cristae and tubules, and few small, dark bodies. The amount of sarcosomes is approximately equivalent to that of myofibrils. As seen in longitudinal sections of muscle fibers, often the junctions between successive mitochondria and both indentations of mitochondria and of the nuclear envelope occurred at the level of the Z bands. This gave the impression that contraction of the myofibrils shortened the nucleus and caused it to wrinkle. Most mitochondrial bulged at their middle as if they had been compressed between successive Z bands, suggesting a more resistant area at the level of these bands than in the rest of the myofibril. Almost no glycogen granules were found, probably because the high metabolic rate of the heart did not allow free storage of such carbohydrates. The administration of DNP was responsible for changes in the ECG (tachycardia and other alterations) and in the structure of the myocardium: large dilations in the sarcoplasmic reticulum and the appearance of small spaces in the mitochondria.

The lymphatic system of the sloth (Bradypus tridactylus) was described after the study of five specimens captured in Brazil. The lymphatic system was injected with Prussian blue suspension and neoprene latex (the latter followed by partial corrosion). The description includes lymph nodes, lymphatic networks, vessels and trunks. The distribution of these structures follows the general pattern of other Xenarthra, namely, Dasypus, Euphractus and Tamandua. However, the following peculiarities were noted: the submandibular, popliteal and posterior mediastinal ll.nn., the abdominothoracic subcutaneous lymphatic collecting vessels, the true principal lymphatic trunks, the cisterna chyli, and the thoracic duct were missing in Bradypus tridactylus. The mesenteric ll.nn. do not fuse and their efferent vessels intermingle with those originating from the cecocolic ll.nn. forming a mesenteric lymphatic plexus. The lymphatic vessels arising from the submucous network of the descending and sigmoid colon are arranged as parallel lamellae similar to those in Dasypus. The efferent collecting vessels from several abdominal organs ultimately empty directly in the inferior vena cava and its trunks of origin and those coming from the bronchial ll.nn. lead to the azygos vein. This feature reminds one of the conditions described in some monkeys. The mesenteric postlymphonodal plexus is well developed and because of the absence of intercalated lymph nodes in the labrinthine circulation it resembles that of amphibia and birds.

The promontory has been studied in two series of adult cadavers (155 in Brazil and 82 in the United States) amounting to 237. The material included whites, Negroes, and Mulattoes of both sexes. The pelvic promontory was considered as the ventral most prominent median point of the lumbosacral region, belonging to the superior pelvic aperture. Even though it is more frequently located at the superior border of the first sacral vertebra, the pelvic promontory can be found at the level of the disc between the last lumbar vertebra and the first sacral vertebra. It is very rarely found either at the inferior border of the last lumbar vertebra or at the inferior border of the first sacral vertebra or the superior border of the second sacral vertebra. No racial or sexual differences were found, but in adults the promontory more frequently has an inferior situation than that of the fetus and newborn (disc between the last lumbar vertebra and the first sacral vertebra). In the first ages, as well as in adult cases where the pelvic promontory is located in the inferior border of the last lumbar vertebra or in the disc caudal to it, the terminal line has four portions: "discal", sacral, iliac, and pubic.

Branches of the coronary arteries of normal human hearts, supplying both atria and ventricles, were found by fine dissection and have been named rami atrioventriculares. They comprise atrial branches from ventricular arteries and ventricular branches from atrial arteries. Their incidence was 74% in the 50 adult individuals studied. The subjects had committed suicide with a poison which did not damage the coronary arteries. The atrioventricular branches constitute communications across the coronary sulcus, thus establishing a continuity between the atrial and the ventricular arterial supply. Therefore, there is not invariably a sharp demarcation of blood supply between atria and ventricles, as has been commonly taught. Neither atrial nor ventricular branches consist exclusively of ascending and descending branches of the coronary arteries, as has been assumed. Atrioventricular branches can play a role in collateral circulation and may, in individuals who are born with them, provide an explanation for some of the variability in signs and symptoms incidental to heart attacks.

Adult sloths (Bradypus tridactylus) were studied by electrocardiography and by light and electron microscopy under normal conditions and under experimental conditions as provided for by injection of 2,4-dinitrophenol (DNP) and ether anesthesia. ECG's of the animals indicated heart rates of 45–71/min, which can be considered as the normal heart rate of the sloth under laboratory conditions. Under normal conditions, the contracted ventricular myocardium of the sloth exhibited (a) a wrinkled sarcolemma, (b) the usual pattern of myofibrils and of sarcoplasmic reticulum, (c) small mitochondria with spiked and branched, often anastomosed cristae, including a few small intramitochondrial dark bodies, (d) an amount of sacrcosomes smaller than the amount of myofibrils, (e) many glycogen granules, isolated, in the form of a chain, or as clusters, in subsarcolemmal, intermyofilamentous and perimitochondrial positions, (f) few multivesicular bodies and (g) large flat sections of the transverse tubular system. Injection of DNP (1 mg/kg) caused tachycardia. With ether anesthesia, the ECG showed monophasic action potential of myocardial injury and prolongation of inter or intraventricular condition. Electrically, the sloth's heart responded to hypoxia as do other mammalian hearts. The administration of DNP produced (a) derangement and reduction in number and length of the mitochondrial cristae, (b) disappearance of spikes, connections between the cristae and, consequently, the honeycombed arrangement, (c) increased matricial space in the center of mitochondria which was often filled with a grayish substance, (d) disappearance of small dark intramitochondrial granules, (e) depletion of glycogen particles and (f) few dilations in the sarcoplasmic reticulum.

The lymphatic system of 45 Didelphys azarae and 15 Didelphys marsupialis, both species found in Brazil, were studied after injection of Prussian blue suspension and neoprene latex (the latter followed by partial corrosion). The data concern the lymph nodes, the lymphatic networks, vessels and principal trunks. The lymph nodal system in Didelphys is less developed (several nodes are missing) than that of the rodents of the same size. In Didelphys, the posterior cranial mediastinal lymph nodes are well developed: the right node receives the lymph from the stomach and diaphragm through vessels draining the para-esophageal, anterior mediastinal and caudal bronchial nodes, a fact not yet observed in other mammals. Each organ or area has its own lymph nodal station. The posterior para-aortic lymph nodes are almost always absent in the males, while in females only the right one is found. The common iliac lymph nodes are missing and it seems that they are replaced by lymphatic dilatations. Only one lymph node is found for the small intestine and two for the large intestine. The lymphatic networks are simple — 4–5 patches are found in the small intestine and one is constant in the terminal ileum. Other features are the separate drainage of each vaginal cornu and the partial duplication of the thoracic duct.

The interrelated processes enabling the ovum to be released from the mammalian ovary have been the subject of many investigations, which resulted in the advancement of several hypotheses; none, however, can as yet totally explain the morphophysiologic events leading to and responsible for ovulation.This investigation deals with a comprehensive light and electron microscopic study of the morphologic changes related to ovulation in the rabbit. Moreover, an attempt is made to establish a correlation between the modification of the follicle and perifollicular structures and their most likely causal factors.The morphology of the non-stimulated follicle is illustrated in Figure 1. Following copulation, follicles were removed at 2,4,6,8 and 10 hours, processed for electron microscopy, and comparable electron micrographs taken. As expected, the apex of the preovulatory follicle exhibited the most dramatic changes since it is the site where ovulation takes place.

UNTIL recently, little was known about the mechanisms responsible for gastrointestinal motility. At the turn of the century, Bayliss and Starling 1 described peristalsis as a wave of relaxation followed immediately by a wave of contraction which moved the bolus of food along the digestive tract. Although this phenomenon can be demonstrated to occur in the intestinal tract of some lower animals, present evidence suggests that comparable peristaltic waves occur only in the esophagus of man. In the small intestine of man peristalsis consists of a coordinated wave of activity in which contraction of the outer longitudinal muscle is 90° out of phase with that of the inner circular muscle. The circular muscle narrows the lumen while the longitudinal muscle opens the lumen and shortens the segment of the bowel involved. Gastrointestinal motor activity has been characterized as either propulsive, as previously described, or pendular. Pendular movements, also known as