Morphological characteristics of the rat thymus duringperinatal protein deprivation and early refeeding: a qualitative and quantitative study

Protein malnutrition is particularly deleterious in young individuals. An immunodeficient state is a well‑known functional consequence but alterations in thymic morphology remain unknown. Our aim is to analyze morphological characteristics of the rat thymus in a perinatal undernutrition and renutrition model – we hypothesize these morphological alterations are reversible with early refeeding. Ninety-day-old Wistar rats were allowed to mate and divided into three groups: nourished (N – normal 20% protein diet), undernourished (UN – pre- and postnatal 5% protein diet until post-natal day 60 – PND 60) and renourished (RN – as UN but normal diet from PND 21 to 60). The thymi of 10 pups/group were submitted to macroscopic, histology, morphometry and scanning electron microscopy analyses. Body weight was highest in N and lowest in UN animals as expected but the thymic/body weight ratio remained similar in N and UN; this ratio was significantly higher in the RN group. UN thymi had a prevalence of type I collagen fibers, atrophic lobules and absence of a clear corticomedullary boundary. Thymic cortical component was decreased in UN. Apoptotic thymocytes were more frequently visualized in the UN thymi. N and RN thymi exhibited very similar morphology. Perinatal protein malnutrition induces drastic morphological alterations in rat thymi but these could be largely reversed with early renutrition. Functional studies are needed to assess if organ function mimics morphology in its recovery.

Effects of protein malnutrition on muscle fibers of the brachial biceps and medial pterygoid of Wistar rats

Protein malnutrition is a public health problem, and in childhood, it can lead to muscle deficits. Here, our objective was to evaluate the effects of malnutrition upon the muscle fibers in the medial pterygoid and braquial biceps. Ten just weaned rat pups that had been born to parents fed a nourished or malnourished diet (N = 5 per group) were studied. The medial pterygoid and braquial biceps muscles were removed and crosssectioned, and histological staining with picrosirius and histochemistry reaction with nicotinamide adenine dinucleotide - tetrazolium reductase (NADH-tr) were performed. The samples stained with picrosirius were observed under polarized light, and from the qualitative analysis, we observed that type I collagen fibers were only present in the braquial biceps muscles of the nourished animals. The NADH-tr reaction indicated that the pterygoid muscle specimens from the malnourished pups lacked intermediate muscle fibers. The crosssectional area of the muscle was lower in the malnourished group than in the nourished group. The density of muscle fibers was higher in the malnourished group than in the nourished group. The consequences of malnutrition were visible when comparing the muscles. We concluded that the differences in daily muscle action along with the differences in embryological origin are instrumental in establishing the results.

Dietary sodium intake induced myenteric neuron hypertrophy in Wistar rats

In the present study we investigated the effect of salt intake on myenteric neuron size of the colon of adult male Wistar rats. The animals were placed on either a high-salt (HS; 8 percent; 12 animals) or a low-salt diet (LS; 0.15 percent; 12 animals) for 15 or 52 weeks and blood pressure was measured. The sizes of myenteric neurons of the distal colon from both groups were measured. No difference in neuron size was observed between the HS and LS groups after 15 weeks. After 52 weeks on HS, neuron size was increased (P<0.005) when compared with the LS group. The rats also presented hypertension, which was significantly different at 52 weeks (142 +/- 11 vs 119 +/- 7 mmHg). These results suggest that a long time on an HS diet can significantly increase myenteric nerve cell size.

Studies on the intrinsic nervous system of the wild rodent Calomys callosus digestive tract. II. The submucous plexus

The submucous plexus of the normal small and large intestine of Calomys callosus was studied by NADH and AChE histochemical techniques and by transmission and scanning electron microscopy. The plexus contains (X + SD) 7,488 + 293 neurons/cm2 in the duodenum, 5,611 + 836 in the jejunum, 2,741 + 360 in the ileum, 3,067 + 179 in the cecum, and 3,817 + 256 in the proximal colon. No ganglia or nerve cell bodies were seen in the esophagus, stomach, distal colon or rectum. The neurons are pear-shaped with a round or oval nucleus and the neuronal cell profile areas were larger in the large intestine than in the small intestine. Most of the neurons display intense AChE activity in the cytoplasm. AChE-positive nerve fibers are present in a primary meshwork of large nerve bundles and in a secondary meshwork of finer nerve bundles. At the ultrastructural level, the ganglia are irregular in shape and covered with fibroblast-like cells. The nucleoplasm of the neurons is finely granular with a few condensations of chromatin attached to the nuclear envelope. In the neuropil numerous varicosities filled with vesicles of different size and electron densities are seen. The pre- and post-synaptic membrane thickenings are asymmetric. Characteristic glial cells with oval nuclei and few organelles are numerous. These data provide a detailed description of this submucosal meshwork.

Morphometry and acetylcholinesterase activity of the myenteric plexus of the wild mouse Calomys callosus

The myenteric plexus of the digestive tract of the wild mouse Calomys callosus was examined using a histochemical method that selectively stains nerve cells, and the acetylcholinesterase (AChE) histochemical technique in whole-mount preparations. Neuronal density was 1,500 + 116 neurons/cm2 (mean + SEM) in the esophagus, 8,900 + 1,518 in the stomach, 9,000 + 711 in the jejunum and 13,100 + 2,089 in the colon. The difference in neuronal density between the esophagus and other regions was statistically significant. The neuron profile area ranged from 45 to 1,100 mum2. The difference in nerve cell size between the jejunum and other regions was statistically significant. AChE-positive nerve fibers were distributed within the myenteric plexus which is formed by a primary meshwork of large nerve bundles and a secondary meshwork of finer nerve bundles. Most of the nerve cells displayed AChE activity in the cytoplasm of different reaction intensities. These results are important in order to understand the changes occurring in the myenteric plexus in experimental Chagas' disease.

Eversion of the urinary bladder in the rabbit

No setor de criaçäo de coelhos da DTAEP-F. M. USP foi verificada em uma coelha N.Z.W. adulta a eversäo completa da vesícula urinária. Ao exame macroscópico, a superfície mucosa apresentou-se de coloraçäo avermelhada e com formaçöes papilomatosas de 3 a 7 cm irregularmente distribuídas na porçäo distal do órgäo. Cortes histológicos da área papilomatosa demonstraram uma erosäo da mucosa recoberta por crosta de fibrina e hemáceas em alguns pontos. Preparos histológicos em outras regiöes apresentaram quadro semelhante, com áreas focais de infiltrado inflamatório mais intenso. Tais resultados permitiram concluir um quadro de cistite crônica inespecífica

Number, size and distribution of ganglion neurons in urinary bladder of rodents

Whole-mount preparations of urinary bladders stained with a modified Giemsa technique were obtained from three rodent species (Guinea-pig, Calomys callosus and the C57/BLJ isogenic mouse) to identify andestimate the relative number and size of ganglionic neurons within the wall of the organ. The istribution of the ganglia was not uniform among the three species: ganglia were concentrated around the ureteral orifices in the Guinea-pig, they were scattered throughout the organ in Calomys callosus, and they were oncentrated near the internal urethral orifice in the C57/BLJ mouse. In the Guinea-pig, the size of approximately 50 percent of the neurons lie in the range of 200 to 300 microns2. In Calomys callosus, 40 percent of the neurons lie in the range of 200 to 250 microns2, with 28 percnet in the range of 50 to 100 microns2. For the C57/BLJ mouse, approximately 60 percent of the neurons have an area of 250 to 400 microns2