ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00325.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

We have developed a method by which nuclear shells containing nucleoli can be isolated from membrane‐depleted rat liver nuclei. This method involves the removal of the internal chromatin. This chromatin is expelled from the nuclear shell using combinations of low and high ionic strength buffers. The expelled internal part is subsequently digested with DNase I or micrococcal nuclease. Examination by electron microscopy of the nuclear and the nucleolar structures at various steps of the isolation procedure shows that the nucleoli are anchored in the peripheral lamina by a pedicle that is continuous with an intranucleolar network. This network is masked in situ by nucleolar granules. The pedicle and the network which support the nucleolar DNA are composed mainly of non‐histone proteins insoluble in 2M N

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00326.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Until recently scanning electron microscopes were mainly used to observe surfaces. However, it has been proved that a backscattered electron detector can give an image (BEI) of the specimen's internal structure after heavy metal staining. In this paper, we report how we have applied the silver staining for NOR‐associated proteins to scanning electron microscopy, studying C3H10T1/2 cells in culture. This technique allows to localize, inside the nucleus, the nucleolar arrangement of AgNOR‐associated proteins. In BEI imaging, the silver staining shows several intranucleolar silver spot‐like deposits sometimes associated in “doublets” as on metaphasic chromosomes. These silver grains probably represent the fibrillar centre location, thought to be the interphasic counterpart of the NORs. However, these silver spot granules are more numerous during i

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00327.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Testosterone administration to the spayed immature female rat produces significant changes in the nuclear ultrastructure of the uterine epithelial cells. In general, these changes increase when a higher dose is used. The most intense changes occur in the nucleolus: volume density and volume increase; volume increases in all nucleolar compartments; granular and vacuolar volume density increase; fibrillar center number increase, but a reduction of their individual volume is observed. Condensed chromatin volume density and volume decrease. Nuclear volume, nuclear envelope surface, and nuclear body volume density and frequency remain almost the same. The surface density of the interface between condensed and dispersed chromatin, fibrillar centers and fibrillar component, and condensed chromatin and fibrillar component, show significant variations even with a small dose of testosterone (0.5 mg). Such a dose is unable to change the volume density of condensed chromatin or fibrillar centers. Correlations between our results and biochemical or other morphological data are discussed.

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00328.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

When tissue culture cells were maintained at 37 degrees C in a serum‐free medium for 4 hr no change in the number of coated pits could be detected using ultrastructural techniques. However, the number of coated vesicles was highly significantly increased, being 179% more than in the control cultures. If the cells were put back into a medium supplemented with 5% calf serum, the number of coated pits was unchanged, but the number of coated vesicles decreased and returned to the control level within a few minutes. The same results were obtained when using ligands such as Low Density Lipoprotein or alpha‐2‐macroglobulin which are known to be internalized via coated structures. It is concluded that coated pits appear and disappear at equal rates and that coated vesicles can accumulate independently. It is suggested that this could be due to the presence of a large reserve of soluble clathrin. This pool would have a low turnover rate because cycloheximide did not block coated vesicle accumulation over the period st

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00329.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Seven human pituitary adenomas obtained by transphenoidal surgery were investigated for the intracellular localization of PRL and GH, using the protein A‐gold immunocytochemical technique. Among the seven cases two were prolactinomas, two were GH‐secreting adenomas and three were mixed PRL and GH‐secreting adenomas. When PRL or GH were revealed, immunoreactivity was found in the cellular compartments involved in protein secretion, RER, Golgi apparatus and secretory granules of corresponding secreting cells. An increasing gradient in the intensity of labeling was observed from the RER to the Golgi and to the granules which may correspond to the increasing concentration of the proteins occurring along their secretory pathway. In addition, crinophagy or destruction of secretory granules by the lysosomal system was observed for both secretory cells. Cells displaying simultaneously PRL and GH reactivity were never found, neither in pure nor in mixed adenomas demonstrating that in the different adenomas studied, secreting cells have retained their specificity and differentiation for the secretion of a single ho

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00330.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The distribution of thymulin (FTS‐Zn) was studied in thymuses from normal mice (OF1) or autoimmune mice (NZB). Thymulin localization was investigated using immunocytochemical techniques on sections of GMA and epon‐embedded mouse thymuses. Two monoclonal antibodies were used: anti‐synthetic thymulin and anti‐intracellular thymulin. In the immunofluorescence assay, GMA sections allowed a more subtle localization of thymulin in the cytoplasm of epithelial cells (with a vacuolar pattern) compared to the epon sections (with a homogeneous fluorescence in the cytoplasm). In both cases, the number of labeled cells was greater in the medullary region than in the cortex of the thymus. At the electron microscopic level, immunolabeling of epon ultrathin sections showed ferritin distributed in some of the epithelial cell vacuoles. The two monoclonal antibodies revealed similar distributions of thymulin in the thymus. The results obtained in this study confirm that the amount of thymulin is greater in the epithelial cells of normal compared to autoimmune t

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00331.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Changes in the organization of centrosomes in mouse splenic T lymphocytes stimulated by concanavalin A (con A) were examined by electron microscopy of serial sections. In both resting and stimulated lymphocytes the single centrosome consists of a pair of centrioles, satellite bodies, and pericentriolar material. In resting cell centrosomes the satellite bodies are preferentially associated with, and appear to be attached by short stalks to, one of the centrioles. The satellite bodies are the primary sites of microtubule termination in the resting cell centrosome. During stimulation by con A there is a several‐fold increase in microtubule content. This is correlated with an overall increase in centrosome size, an apparent increase in the size and in the number of satellite bodies, and a redistribution of satellite bodies to occupy a position between the two centrioles. Increased numbers of microtubules are detected terminating on the satellite bodies and in the pericentriolar material of the stimulated cell centrosome. Microtubule assembly from centrosomes in vitro was assessed by electron microscopy using detergent‐permeabilized lymphocytes that had been pretreated to remove endogenous microtubules and supplied with purified bovine brain tubulin. These studies indicate that satellite bodies are major sites of microtubule assembly in both resting and stimulated cell centrosomes and show that the centrosomes of stimulated cells assemble more microtubules in vitro than resting cell centrosomes. This parallels the increase in microtubule content in intact lymphocytes stimulated by con A and suggests that the changes in centrosome organization and microtubule assembly capacity that occur during stimulation are causally rela

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00332.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Aging, aphidicolin, serum deprivation and cytochalasin B induce a decrease in the rate of DNA synthesis, an increase in cell flattening (cell surface increase) and an extension of the cytoplasmic microtubular complex (CMTC). Age and experimental conditions affect the protein content of the cell, but there is no relationship between cell morphology and cell protein content. Serum deprivation, aphidicolin and cytochalasin B are more effective on DNA synthesis and cytoplasmic actin complex (CAC) of late than of early fibroblasts. Despite these facts, the cell morphology of late cells is fairly stable and is not affected by experimental conditions, which exert an “aging effect” upon the cell morphology in earlier cultures. Colchicine acts upon the CMTC, cell morphology and DNA synthesis at all ages of the cultures. It also induces disruption of the CAC, the intensity of the disruption depending on both the length of the treatment and the age of the culture: the sensitivity of the actin‐microfilaments to colchicine increases with the mitotic age of the cells. We suggest that the microtubular integrity is needed, but not sufficient, to preserve the organization of the CAC into microfilaments. We propose a logical model comprising feedback loops between the number of the mitotic cycles, the rate of DNA synthesis, the extention rate of the plasma membranes and CMTC in normal fibroblasts. CMTC is associated, in this model, with the expression of negative or positive controls, depending on the grade of its extension (Fi

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00333.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

An electron microscopic analysis of Tubifex tubifex (Annelida, Oligochaeta) spermiogenesis has revealed the presence of a slanted basal body during the early stages: the centriole has the shape of a cylinder obliquely cut at one extremity. In these stages an anchoring apparatus is also present, similar to the one of primitive spermatozoa, and disappearing in the mature sperm. The slanted centriole in cross section gives images of “incomplete” centrioles similar to the ones reported in the literature and interpreted as images of centriologenesis. The transient anchoring apparatus is interpreted as a rudimentary organelle used during spermiogenesis to maintain the centriole in a correct position. This function in the mature spermatozoon is performed by the mitochond

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1985.tb00334.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY