摘要:

The neuronal selectivity of protargol silver was determined in embedded and cultured nervous tissue by light (LM) and transmission electron microscopy (TEM). Ultra -structurally, silver (85–140 Å in diameter) was found deposited in neuronal, but not glial, perikarya and cell processes. Usually, the silver grains were arranged in elongated arrays that were associated with electron-dense, strand-like structures that correspond to the ‘neurofibrils’ observed in LM; myelin sheaths, mitochondria, Nissl substance, Golgi bodies, synaptic vesicles, and endoplasmic reticulum could be excluded as the basis for neuronal argyrophilia. Unfortunately, the composition of these neurofibrils was obscure because of poor tissue preservation involved with proper impregnation, but they appeared to correspond to microtubules and neurofilaments. Neuronal structures containing a predominance of either organelle were impregnated with protargol. Nuclei and nucleoli of neuronal and nonneuronal cells were densely stained with silver as visualized with LM and TEM. Not every neuron was impregnated with protargol, but under conditions of improper fixation some of these neurons had an electrondense cytoplasm which exhibited a definite affinity for silver. A discussion of protargol selectivity is also pre

ISSN:1422-6405    

DOI:10.1159/000145591

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

The development of premolar tooth germs in dogs, particularly their rotation and crowding, was examined on radiographs, dissected specimens of tooth germs, serial sections stained by Masson-Goldner’s technique and reconstructed models. The materials used were the mandibles of 32 puppies from birth to 6 months, and the species was a highly pedigreed Shiba Inu which has no crowding of the premolars in the mature stage. The results obtained are as follows. (1) Rotations and crowdings of premolars, similar to those in brachygnathus dogs and wolves raised in captivity, were observed during ontogenesis of dolichocephalic dogs, whose adult state exhibits no crowding of teeth. (2) The type of rotation was B (the mesial portion is rotated buccally) for the second and third premolars and L (the mesial portion lingually) for the fourth premolar. (3) The rotations of the premolars did not coincide with those of their deciduous predecessors. (4) These rotations appeared in the bud and cap stages of premolars, before the formation of roots of deciduous molars. The premolars developed crowding at 5 months when they increased in dimensio

ISSN:1422-6405    

DOI:10.1159/000145592

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

Histochemical and ultrastructural aspects of adipocyte differentiation in subcutaneous tissue of fetal pigs were analyzed in a longitudinal study. A matrix of collagen fibers surrounding adipocytes developed after the establishment of a distinct and continuous PAS-positive basement membrane. The degree of plasma membrane invagination and specialization was positively correlated with the extent of basement membrane and collagen matrix formation. Close spatial relationships between narrow, smooth endoplasmic reticulum, plasma membrane invaginations, the surface of lipid droplets and mitochondria were observed in differentiating adipocytes. Histochemical and ultrastructural criteria for the identification of preadipocytes are: (1) perivascular location; (2) mitochondria localized in the Golgi zone; (3) cytosolic glycogen; (4) rough endoplasmic reticulum with cisternae uniformly and approximately 600 Å wide; (5) free ribosomes and few polysomes, and (6) lipid droplets encased by microfilaments. These criteria permitted clear distinction from obvious fibroblasts and macrophages. Other stromal cells were morphologically abnormal. Occasionally, adipocytes and perivascular cells exhibited close intercellular contacts that were morphologically distinct from intercellular contacts between contiguous endothelial cells

ISSN:1422-6405    

DOI:10.1159/000145593

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

Staining and histochemical methods, immunofluorescence, and electron microscopy were used to individualize the somatotropic cells in the adenohypophyseal pars distalis of the non-hibernating hedgehog. One cell-type was differentiated; their characteristics at the light and electron microscopic levels were presented. Immunofluorescence has confirmed the functional significance of this cell-type and the validity of the denomination ‘somatotropic cells

ISSN:1422-6405    

DOI:10.1159/000145594

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

The pars distalis of the pituitary gland was studied by means of electron microscopy in 14- to 18-day dwarf embryos (dw/dw) obtained from matings of dwarf homozygotes in which reproductivity was induced by hormone supplementation and pituitary transplants to the renal capsule. At 14 days of gestation the dwarf pars distalis shows fewer granulated cells than in the normal. Although somatotroph-like and mammotroph-like cells are identifiable in the normal pars distalis as early as 15 days, comparable cells are not present in the dwarf. By 17 and 18 days, the dwarf exhibits an ambiguous cell-type with a combination of somatotroph and mammotroph characteristics. At 18 days the dwarf also continues to show numerous nongranulated cells with large aggregates of glycogen, whereas in the normal pars distalis comparable glycogen-containing cells are relatively scarce.

ISSN:1422-6405    

DOI:10.1159/000145595

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

Alizarin red S (ARS) is used for histological characterization of calcium. In order to improve the conditions of the use of the dye on biological materials, the chemical reaction between ARS and Ca2+ is studied in vitro. In aqueous solution ARS and Ca2+ ions precipitate to form brick-red deposits. For precipitation to occur a neutral pH (4 < pH < 8) is required; the stoichiometric ratio is 1:1. ARS reacts with calcium via its sulfonate and hydroxyl groups. The apparent solubility product is around 10∼7 Na+ and K+ ions do not interfere with equilibrium of the precipitation reaction but Mg2+ and soluble proteins such as bovine serum albumin react with ARS and form soluble complexes which can lead to a decrease in the ARS quantity available to react with the calcium ion

ISSN:1422-6405    

DOI:10.1159/000145596

出版商:S. Karger AG    

年代:1982

数据来源: Karger