Comportamento de tecidos à implantação de partículas esféricas de limalha

Introduction os spherical alloys particles (size range from 15 to 70 micra) in the back at the level of the first thoracic vertebra of 24 male rats, 60 days old, for a period of time of 12, 13, 14 and 15 months, shows no alteration in the connective tissue, striate muscle, fatty tissue, brown fatty tissue, nerve fibres and hair follicle.

Histological description of the midgut and the pyloric valve of Tropidacris collaris (Stoll, 1813) (Orthopetera: Romaleidae)

The present research describes the histology of the midgut, gastric caeca, and pyloric valve of Tropidacris collaris (Stoll, 1813), (Orthopetera: Romaleidae). We used light microscopy, staining (Gomori's trichrome and periodic acid-Schiff (PAS)), and a routine histological analysis method (hematoxilin-eosin). The insects were obtained from, and also bred in, the Laboratory of Entomology, Department of Biology, of the Rural Federal University of Pernambuco (UFRPE). The collected material was fixed in alcoholic Boüin and embedded in paraplast. The results demonstrated that the midgut wall is composed of an inner epithelial layer and two outer layers of striate muscles: one internal (circular) and the other external (longitudinal), with connective tissue between the muscle fibers. The epithelium is single-layered, with two cell types: regenerative and elongated columnar. The gastric caeca presents muscle layers similar to those of the midgut. Simple columnar epithelium lines the gastric caeca, which presents villi and projects towards the lumen. The pyloric valve is of striate muscle tissue, covered by a single epithelial-cell layer.

GDNF and neurturin are target-derived factors essential for cranial parasympathetic neuron development

During development, parasympathetic ciliary ganglion neurons arise from the neural crest and establish synaptic contacts on smooth and striate muscle in the eye. The factors that promote the ciliary ganglion pioneer axons to grow toward their targets have yet to be determined. Here, we show that glial cell line-derived neurotrophic factor (GDNF) and neurturin (NRTN) constitute target-derived factors for developing ciliary ganglion neurons. Both GDNF and NRTN are secreted from eye muscle located in the target and trajectory pathway of ciliary ganglion pioneer axons during the period of target innervation. After this period, however, the synthesis of GDNF declines markedly, while that of NRTN is maintained throughout the cell death period. Furthermore, both in vitro and in vivo function-blocking of GDNF at early embryonic ages almost entirely suppresses ciliary axon outgrowth. These results demonstrate that target-derived GDNF is necessary for ciliary ganglion neurons to innervate ciliary muscle in the eye. Since the down-regulation of GDNF in the eye is accompanied by down-regulation of GFRα1 and Ret, but not of GFRα2, in innervating ciliary ganglion neurons, the results also suggest that target-derived GDNF regulates the expression of its high-affinity coreceptors.

EFFECTS OF OVARIAN HORMONES ON THE CONTENT AND DISTRIBUTION OF CATION IN INTACT AND EXTRACTED RABBIT AND CAT UTERUS

The uteri of rabbits and cats have been analyzed for sodium, potassium, and chloride, usually after various preliminary treatments with estrogen and progesterone. These tissues contain less potassium (50–80 meq./kg.) than striate muscle and more sodium (75–118 meq./kg.) than other highly cellular tissues. It appears that this cation composition can be attributed in part to a relatively large extracellular fluid volume (EFV).Various methods have been used to estimate the EFV in these tissues. The radiosulphate space (in vitro) does not appear to be reliable as a measure of extracellular space. The chloride space varies, but exceeds 400 ml./kg. in all cases, and in some approaches 700 ml./kg. Inulin space (in vitro) is about 60% of the chloride space, which in turn is usually smaller than the sodium space. The chloride space appears to provide the best approximation to the EFV since its volume of distribution rarely exceeds the sodium space, and since chloride (but not sodium) can be removed completely on leaching in isotonic sucrose.Calculated cellular potassium concentrations are as high as or higher (150–210 meq./l.) than in striate muscle. Apparently the low total tissue potassium concentration is a consequence of the large EFV.Appreciable quantities of sodium (20–50 meq./l.) reside outside of the chloride space in most cases, presumably in cellular water. Furthermore, a residue of sodium remains in uterine tissue after leaching in isotonic sucrose or choline chloride. With appropriate leaching procedures, an initial rapid depletion of tissue sodium is followed by a period of relatively slow loss, indicating derivation of sodium from at least two separate tissue spaces. Equilibration in isotonic potassium chloride causes nearly complete equilibration of potassium and chloride throughout tissue water, but does not remove residual sodium, suggesting chemical binding rather than Donnan distribution as the mechanism of sodium retention.The effects of estrogen and progesterone on the concentrations of cations in uterine cells are shown to be relatively small. Estrogen causes expansion of the cellular compartment relative to the extracellular space in both rabbit and cat and decreases the concentration of cation (per liter of tissue water and per liter of intracellular fluid). Progesterone treatment, given after estrogen, interfered with the ready entrance of chloride into the cellular space of rabbit uterus exposed to isotonic choline chloride. Cat uterus was not so affected, there being very little penetration of chloride even after estrogen alone.

EFFECTS OF OVARIAN HORMONES ON THE CONTENT AND DISTRIBUTION OF CATION IN INTACT AND EXTRACTED RABBIT AND CAT UTERUS

The uteri of rabbits and cats have been analyzed for sodium, potassium, and chloride, usually after various preliminary treatments with estrogen and progesterone. These tissues contain less potassium (50–80 meq./kg.) than striate muscle and more sodium (75–118 meq./kg.) than other highly cellular tissues. It appears that this cation composition can be attributed in part to a relatively large extracellular fluid volume (EFV).Various methods have been used to estimate the EFV in these tissues. The radiosulphate space (in vitro) does not appear to be reliable as a measure of extracellular space. The chloride space varies, but exceeds 400 ml./kg. in all cases, and in some approaches 700 ml./kg. Inulin space (in vitro) is about 60% of the chloride space, which in turn is usually smaller than the sodium space. The chloride space appears to provide the best approximation to the EFV since its volume of distribution rarely exceeds the sodium space, and since chloride (but not sodium) can be removed completely on leaching in isotonic sucrose.Calculated cellular potassium concentrations are as high as or higher (150–210 meq./l.) than in striate muscle. Apparently the low total tissue potassium concentration is a consequence of the large EFV.Appreciable quantities of sodium (20–50 meq./l.) reside outside of the chloride space in most cases, presumably in cellular water. Furthermore, a residue of sodium remains in uterine tissue after leaching in isotonic sucrose or choline chloride. With appropriate leaching procedures, an initial rapid depletion of tissue sodium is followed by a period of relatively slow loss, indicating derivation of sodium from at least two separate tissue spaces. Equilibration in isotonic potassium chloride causes nearly complete equilibration of potassium and chloride throughout tissue water, but does not remove residual sodium, suggesting chemical binding rather than Donnan distribution as the mechanism of sodium retention.The effects of estrogen and progesterone on the concentrations of cations in uterine cells are shown to be relatively small. Estrogen causes expansion of the cellular compartment relative to the extracellular space in both rabbit and cat and decreases the concentration of cation (per liter of tissue water and per liter of intracellular fluid). Progesterone treatment, given after estrogen, interfered with the ready entrance of chloride into the cellular space of rabbit uterus exposed to isotonic choline chloride. Cat uterus was not so affected, there being very little penetration of chloride even after estrogen alone.

Responses of Smooth and Striate Muscle to Alterations in Extracellular Electrolytes

Alterations in plasma electrolyte concentrations were produced by potassium deficiency, by adrenalectomy and by administration of cortisone and Adrenalin. The effect of these procedures on thigh and stomach muscle electrolytes was compared. Differences in response of the two types of muscle were analyzed and the conclusion drawn that different mechanisms control electrolyte composition of smooth and skeletal muscle. Implications of this are discussed. Calculations are presented which suggest that cortisone and Adrenalin enhance the potassium concentrating ability of skeletal muscle cells and that Adrenalin, in addition, restores the ability of muscle cells from adrenalectomized animals to exclude sodium.