PubMed Health⌕ Search

Biomedical subjects

G Goessens

Publications and source records attributed to G Goessens.

At least 37 records · Page 2Linked to original sources
PubMed1986

[Nucleolar vacuoles observed in rat oocytes].

Recently Merveille and al (1984) using light microscope have observed intranucleolar cavities in rat ovocytes from large antral follicles. They have showed that the frequency of these vacuoles increases when follicular growth is stimulated by gonadotropins. In this paper, the ultrastructure of the nucleolar cavities has been studied. Two types of cavities are visible in these nucleoli: 1. nucleolar "interstices" present at the periphery of the nucleoli in remnants of the granular component and of the dense fibrillar components; 2. nucleolar "vacuoles" which are located in the homogeneous substance forming the greatest part of the nucleolus. The nucleolar vacuoli generally are clear-cut and spherical. The density of their content is similar to the nucleoplasm but they don't communicate to the nucleoplasm. By means of cytochemical to detect Ag-NOR proteins (Ploton and al [1983]) and basic proteins (Sheridan and Barnett [1984]), dense fibrillar component of the nucleolus but no basic proteins may be seen in the wall of the cavity. Moreover no evidence of relation between the presence of the vacuoles and the process of follicular atresia has been found.

Animals↗
PubMed1985

Heart structure and ventricular ultrastructure of hemoglobin- and myoglobin-free icefish Channichthys rhinoceratus.

The structural and ultrastructural characteristics of the heart of Channichthys rhinoceratus, an antarctic teleost devoid of respiratory pigments, are described and compared with those obtained from the red-blooded related species Notothenia rossii. The heart of the icefish is characterized by a spongy myocardium supplied with a highly developed arterial coronary system. This vasculature includes a subepicardial system and an extensive intratrabecular capillary network. Arterial hilar network and Thebesian vessels may also be present. The bulbus arteriosus shows unusually large spheroid structures located in the middle layer of the wall. Both white- and red-blooded species display comparable myocardial cell morphology and organelle distribution. However, the mitochondrial cristae of the former are more densely packed and the sarcolemma possesses numerous caveolae. A large proportion of non-contractile cells is also found in the icefish ventricular wall.

Adaptation, Physiological↗
PubMed1985

Effects of osmotic shocks on the ultrastructure of different tissues and cell types.

This study deals with the effects of hyper- and hypo-osmotic media on the ultrastructure of four different types of cells and tissues: rat pheochromocytoma cells of line PC12, mouse Ehrlich ascites tumor cells, rat kidney cortex and intestine. Application of hyper-osmotic conditions induces in the nuclear compartment of the tested cell types a condensation of chromatin, a ruffling of the nuclear envelope with loosening of condensed chromatin from the lamina, and an apparent loss of nucleolar fibrillar component which disappears in a background of diffuse granular material. In hypo-osmotic media, there is a marked decondensation of chromatin and a fragmentation of the granular material of the nucleolus. As far as the cytoplasmic compartment is concerned, the electron density of the cytosol is markedly increasing when going from hypo- to hyper-osmotic conditions and there is no vacuolization in hypo-osmotic media. In kidney cortex slices, application of hypo-osmotic shocks further results in a marked reduction of the extracellular space delimited by the infoldings of the tubular cells plasma membranes. These modifications are discussed in relation to the volume regulation process and the changes in ion concentration that occur in cells submitted to anisosmotic media.

Animals↗
PubMed1985

Effects of 2-mercapto-1-(beta-4-pyridethyl)-benzimidazole (MPB) on Ehrlich cell nucleoli: stereological analysis.

The effects of MPB, a strong inhibitor of RNA synthesis, have been analysed at the ultrastructural level by means of stereological methods. After treatment, an increase in the nucleolar volume is observed. This enlargement is due to vacuolization of the nucleoli. However, the relative volumes of the nucleolar components are modified in various directions: the volume of the granular component decreases whereas the fibrillar centres increase in size. These results are discussed in terms of relations between morphology and function of the nucleolus.

Animals↗
PubMed1985

Re-evaluation of the site of transcription in Ehrlich tumour cell nucleoli.

Recent electron microscopic immunolocalization studies (Scheer and Rose, 1984) indicated that RNA polymerase I is located in, and probably confined to, the fibrillar centres of the nucleoli. This conclusion appears to be in contradiction to previous autoradiographic studies reporting that transcription of rRNA genes takes place in the dense fibrillar component. Despite the fact that rRNA transcription occurs in the dense fibrillar component of Ehrlich tumour cell nucleoli, we show in the present paper that dense fibrillar component containing rapidly labelled RNA can be visualized not only around but also inside the fibrillar centres.

Animals↗
PubMed1984

Nuclear bodies in mouse lymphoid cells stimulated by lipopolysaccharide.

C57 BL/6J mouse spleen lymphocytes have been stimulated by a polyclonal mitogene, the lipopolysaccharide of E. coli (LPS). Depending on the LPS concentration, two pathways of B lymphocyte differentiation can be obtained. At low dose, the population is mainly composed of blast cells (85%) and at a high dose, the latter transforms into plasma cells (80%). Four types of nuclear bodies have been distinguished and quantitatively studied at several stages of cell differentiation. Only the simple nuclear bodies type A, which could be related to the nuclear matrix, show quantitative modifications in small lymphocytes. Connections between granular nuclear bodies (type D) and nucleolar material have been observed. Some granular nuclear bodies exhibit a morphological zone similar to the nucleolar fibrillar centre as well as fibrillar and granular components. Autoradiographic studies indicate that the granular nuclear bodies contain RNA synthesized elsewhere in the nucleus and that this RNA subsequently migrates to the cytoplasm. Furthermore connections between granular nuclear bodies and chromatin have also been observed.

Animals↗
PubMed1981

[Study of human synovial cells in culture].

Normal human synovial cells are cultivated in vitro; they actively multiply and fibroblast-like cells with structural characteristics of intermediate synoviocytes are obtained. In view of analyzing some functional aspects of this cell line, their endocytotic capacities have been studied. They also have been cultivated in a medium deprived of serum; a new cell type develops ("dendritic cells"). The latter are analyzed (cell division, endocytosis). As a comparison, human pulmonary fibroblasts (W I 38 line) and mouse macrophages are cultivated and studied under the same experimental conditions.

Culture Techniques↗
PubMed1979

Localisation of nucleolus-organizing regions in interphase cells.

A technique based on the use of silver solutions, which selectively stains the nucleolus-organising regions (NORs) in chromosomes, was applied to interphase Ehrlich tumour cells. The results indicate that nucleolar fibrillar centres correspond to the NORs.

Animals↗
PubMed1976

The nucleolar fibrillar centres in various cell types in vivo or in vitro.

Nucleoli were studied in chick fibroblasts cultured in vitro, under normal or under experimental conditions, and in several mammalian cell types in vivo. All these cells frequently contain nucleoli with fibrillar centres. The nucleolar fibrillar centres are composed of fibrous material of low electron density and are always intimately associated with the dense fibrillar component. Their morphology is very similar to that analysed cytochemically in Ehrlich tumour cells. It therefore appears that they could be related to the nucleolar organizers as suggested in Ehrlich tumour cells.

Animals↗
PubMed1976

Comparative ultrastructural study of the effects of serum-free medium and dibutyryl-cyclic AMP on newborn rat astroblasts.

Modifications of cell shape induced in cultured newborn rat astroblasts by serum deprivation or dibutyryladenosine 3'-5' monophosphate (dBcAMP) are described. Serum suppression modifies the adhesitivity of the cells to the substrate, but this modification is not consistent with a true differentiation. The main ultrastructural feature of dBcAMP-treated astroblasts is the presence of an extensive system of 90 A microfilaments, while control cells are relatively devoid of these structures.

Animals↗