Location of rRNA gene transcription sites within Ehrlich tumor cell nucleoli.

in Bulletin de l'Association des Anatomistes (1991), 75(229), 33-7

The nucleolus is the morphological visualization of ribosome biogenesis. The spatial distribution of nucleolar DNA has been investigated in Ehrlich tumor cells by various immunogold labelling techniques ... [more ▼]

The nucleolus is the morphological visualization of ribosome biogenesis. The spatial distribution of nucleolar DNA has been investigated in Ehrlich tumor cells by various immunogold labelling techniques. The DNase 1-sensitive regions within the nucleolus have been identified by in situ nick-translation at the ultrastructural level. The precise nucleolar location of rDNA and rRNA has been further specified by in situ hybridization and electron microscopy. Our results indicate that the fibrillar centers are the sole nucleolar structures where DNase 1-hypersensitive sequences, rDNA and rRNA are located together. These findings strongly suggest that rRNA gene transcription takes place within the confines of the fibrillar center, probably close to the boundary regions to the surrounding dense fibrillar component. [less ▲]

Le mélanome B16 de la souris en culture à trois dimensions

in Bulletin de l'Association des Anatomistes (1986), 70(210), 21-4

Multicellular spheroids composed of mouse B16 melanoma cells have been prepared in non agitated culture on solid agar. Cells present frequent contacts and an extracellular matrix appears during ... [more ▼]

Multicellular spheroids composed of mouse B16 melanoma cells have been prepared in non agitated culture on solid agar. Cells present frequent contacts and an extracellular matrix appears during cultivation (up to 2 months in agitated suspension); it contains laminin, fibronectin and collagen I, III and IV. Cellular differentiation takes place inside these spheroids (melanogenesis progressively increases), but a relatively intense cell proliferation rate is also maintained. [less ▲]

Fixation de ferritine cationisee a la surface des cretes palatines du rat.

in Bulletin de l'Association des Anatomistes (1982), 66(192), 117-25

Recently, we suggested that the cell coat of the surface epithelial cells of the palatal shelves and especially its sialyl groups are implied in the adhesion process which initiates the constitution of ... [more ▼]

Recently, we suggested that the cell coat of the surface epithelial cells of the palatal shelves and especially its sialyl groups are implied in the adhesion process which initiates the constitution of the secondary palate. In this work, use of cationized ferritin which interacts with anionic receptors of the plasma membrane give us the possibility to render these sialic acids visible. After five minutes incubation in presence of cationized ferritin, the labeling particles are distributed in monolayer over the plasmalemma of epithelial cells. Subsequent incubation in cationized ferritin free medium results in clustering of the marker followed by the detachment of the labeled patches. Otherwise, incubation in the presence of neuraminidase from Clostridium perfringens before the polycationic ligand contact prevents labeling. We think that lateral migration modifications of the anionic receptor could be associated with changes of the shelves capacity to adhere. [less ▲]

Etude ultrastructurale des effets de la neuraminidase sur des processus palatins de rat.

in Bulletin de l'Association des Anatomistes (1981), 65(190), 329-39

In a previous work, we demonstrated that palatine processes treated with 10 micrograms/ml neuraminidase for 30 minutes at 37 degrees C show a delayed fusion in vitro. In order to investigate the effects ... [more ▼]

In a previous work, we demonstrated that palatine processes treated with 10 micrograms/ml neuraminidase for 30 minutes at 37 degrees C show a delayed fusion in vitro. In order to investigate the effects of neuraminidase, the treated palatine processes were observed with the aid of transmission and scanning electron microscopy. The effect of neuraminidase is exclusively detectable on superficial flat cells of the palatine processes, especially the cells of the medial edge of the process. The epithelial basal cells remain unchanged. Observed with the S.E.M., the superficial epithelial cells show bubbles, become spherical and detached. To explain these observations, we namely propose the following hypothesis: the action of neuraminidase prevents the fusion of the palatine processes because it denudes basal cells bearing a too immature cell coat for ensuring sufficient adherence between the palatine processes. [less ▲]

Considerations sur les structures dites lamellaires de l'oeuf de rat non feconde.

in Bulletin de l'Association des Anatomistes (1980), 64(185), 173-81

The ultrastructural study of the unfertilized Rat egg ooplasm has shown that the so-called lamellar structures are in fact filaments constituted of proteins and where no ribonucleic acid can be detected ... [more ▼]

The ultrastructural study of the unfertilized Rat egg ooplasm has shown that the so-called lamellar structures are in fact filaments constituted of proteins and where no ribonucleic acid can be detected. Thus, they do not represent a particular organization of polyribosomes. These filaments could be considered as protein stockage, maybe from membranous origin, ready for use during segmentation. Several figures suggest that endocytotic vesicles and vacuoli constitute the source of the filamentous material. [less ▲]

Etude des polysaccharides presents dans les cretes palatines du rat peu avant leur fusion.

in Bulletin de l'Association des Anatomistes (1978), 62(176), 65-76

When slices of rat palatal shelves removed by dissection from 16 days 8 hours old fetuses, just before fusion, are treated by the periodic acid Schiff reaction (PAS), colored substances may be detected ... [more ▼]

When slices of rat palatal shelves removed by dissection from 16 days 8 hours old fetuses, just before fusion, are treated by the periodic acid Schiff reaction (PAS), colored substances may be detected especially in the epithelium of the potential fusion zone; these substances are normally observed at the free surface of the epithelium. Our histochemical research, realized with the aid of the photonic microscope and of the transmission electron microscope, shows that most of the PAS positive material consists in glycogen; at the surface, this polysaccharide remains in the cytoplasm of flat degenerating cells and cannot be confused with the "cell coat" which presents no particularity, at this level, after demonstration by ruthenium red and by lanthanum nitrate. [less ▲]

Etude au microscope electronique a balayage et a transmission de l'epithelium amniotique chez la ratte en fin de gestation.

in Bulletin de l'Association des Anatomistes (1977), 61(172), 81-91

The pattern of the amniotic epithelium during the eight last days of pregnancy is described with the aid of scanning and transmission microscopy. A flattening of the cells appears near the term. Their ... [more ▼]

The pattern of the amniotic epithelium during the eight last days of pregnancy is described with the aid of scanning and transmission microscopy. A flattening of the cells appears near the term. Their area becomes progressively greater increasing their contact surface with the amniotic fluid. Simultaneaously, their microvilli become more numerous. During the 20th, the 21st and the 22nd days of pregnancy, we observed cytoplasmic processes emanating from the base of the cell interrupting the basal membrane and entering the underlying connective substance. No evidence of cell degeneration was seen. [less ▲]

Etude histoenzymologique des couches cytoarchitectoniques de la moelle de différents mammifères et de l'homme

in Bulletin de l'Association des Anatomistes (1974), 58