PubMed Health⌕ Search

Biomedical subjects

L Andries

Publications and source records attributed to L Andries.

33 records · Page 2Linked to original sources
PubMed1983

The subgerminal yolk surface and its relationship with the inner germ wall edge of the stages X to XIV chick and quail embryo. A SEM study.

SEM reveals that the subgerminal yolk surface of the chick and quail embryo during stages X to XIV possesses microvilli and small pits. Threadlike extensions and globular structures are found on the subgerminal yolk surface mainly in the central area. The cellular nature of the subgerminal yolk was confirmed with TEM that showed the presence of a plasma membrane, mitochondria, micro-invaginations and microfilaments. The ventral cells of the germ wall are yolky and can be attached to the subgerminal yolk surface with filopodial extensions during stages X to XII. From stage XIII, the shape of these cells is usually more flattened and they protrude lamellae and filopodia.

Animals↗
PubMed1983

The dorsal surface of the animal pole of the just laid quail egg, studied with SEM.

The epiblast and the surface of the perigerminal yolk of the just laid quail blastoderm were examined by scanning electron microscopy (SEM). The dorsal surface structures are microvilli, mainly along the cell borders. The scarcity of the dimples does not support that ingression occurs at this stage. Flat or round cells on the epiblast are possibly deep layer cells that failed to incorporate after passing through the epiblast. The majority of the blastoderms have an irregular margin. The large edge cells possess microvilli at their borders only. A few blastoderms, probably the more developed, have a smooth edge with closely packed cells. The margin of these germs shows round cells and lamellae that could be protruded by deep cells. The process of cell rounding and extension of lamellae may be the onset of the formation of the margin of overgrowth. Concentric zones are present on the surface of the perigerminal yolk, on which microvilli and blebs are found near the germ. The presence of cell projections on the perigerminal surface suggests its living nature.

Animals↗
PubMed1981

Resolution in light microscope autoradiography using a carbon-14 labelled line source.

Light microscope autoradiographs were prepared from a 14C line source Two factors that affect resolution were studied: emulsion thickness and section thickness. The distribution around the line source was determined using the half-distance (HD) value to quantify the resolution. An increase in HD value was observed with thicker sections or emulsion layers. The shape of the curve reflecting the grain density distributions around these line sources was very similar. After normalization in HD and relative grain density units, an average distribution was calculated and compared with the shape of normalized density distributions obtained from electron microscope autoradiographs. Other than a discrepancy near the source, an acceptable correlation was observed.

Autoradiography↗
PubMed1980

Alcian blue staining during the formation of mesoblast in the primitive streak stage chick blastoderm.

The distribution of alcian blue (AB) positivity, and its sensitivity to streptococcal and testicular hyaluronidase, were studied in primitive streak stage chick blastoderms. Accumulation of hyaluronate was observed in deep layer (DL) cells and on laterally migrating middle layer (ML) cells. During the formation of the middle layer, a first stage, namely de-epithelialization of the upper layer cells, is recognized and correlated with the absence of hyaluronate. A second stage, namely migration of the de-epithelialized upper layer cells laterally to the edge of the area pellucida, is correlated with the accumulation of AB-positivity. The AB-staining also demonstrated the accumulation of both sulphated and not-sulphated mucopolysaccharides, where a basal lamina is present.

Alcian Blue↗
PubMed1980

Distribution and turnover of testicular hyaluronidase sensitive macromolecules in the primitive streak stage chick blastoderm as revealed by autoradiography.

Primitive streak stage chick blastoderms were cultured for 30 min on a medium containing tritiated glucosamine. Light microscope autoradiography revealed extracellular labeling, and pretreatment of the sections with testicular hyaluronidase suggested the glycosaminoglycan nature of the labeled products. After incorporation of the tritiated precursor, some blastoderms were transferred to a chase medium, and cultured for 30, 90, 210 min. The changes is distribution of the labeled testicular hyaluronidase-sensitive macromolecules during the chase experiment illustrated the ingression of cells in the primitive streak stage chick blastoderm. Grain density differences, resulting from the various chase periods, suggested the renewal of the testicular hyaluronidase-sensitive fraction.

Animals↗
PubMed1980

Localisation and characterization of acid mucopolysaccharides in the early chick blastoderm.

Acid mucopolysaccharides in the extracellular compartment of early chick blastoderms (16 h of incubation) were labelled with tritiated glucosamine and/or [35S]sulphate. The incorporation pattern was studied autoradiographically. Treatment with testicular hyaluronidase revealed a testicular hyaluronidase-sensitive fraction, mainly at the periphery of Middle Layer and Deep Layer cells, and a testicular hyaluronidase-resistant fraction, mainly at the ventral side of the Upper Layer. A biochemical analysis, utilizing chondroitinase ABC and nitrous acid, followed by cellulose acetate electrophoresis, demonstrated the synthesis of a non-sulphated fraction, i.e. hyaluronic acid and/or chondroitin, and a sulphated fraction, comprising two undersulphated components, i.e. chondroitin sulphate, and heparan sulphate or heparin. The appearance of different AMPS in specific areas of the early chick blastoderm is regarded as an early specialization of the extracellular compartment.

Animals↗
PubMed1979

[A fi- tetracyclin resistance plasmid with specific restriction of phages on salmonella typhi, S. paratyphi B and S. typhi-murium (author's transl)].

Among 262 strains of Salmonella typhi from an epidemic outbreak of typhoid fever in Baden-Württemberg in 1974 2 strains were isolated which were tetracyclin resistant and showed no reactions with the Vi testphages T, D6 and VII whilst all other strains belonged to lysotype A, subtype Tananarive. It turned out that the Tc resistance in both strains was caused by a fi- R plasmid which could be transfered to other S. typhi strains, to E. coli K12, S. paratyphi B, S. java and S. typhi-murium as well as from Tc resistant E. coli K12 back to S. typhi. The Tc R plasmid introduced in S. typhi, lysotype A, caused specific restrictions of typing phages T, D6 and VII. Also, the transfer of the plasmids to strains of S. paratyphi B and S. typhi-murium resulted in restrictions of a number of typing phages. Both plasmids had identical patterns of restriction. In this pattern the Tc R plasmid differed from those described in the literature.

Drug Resistance, Microbial↗
PubMed1975

[Phage typing and biotyping of salmonella typhi-murium (author's transl)].

1998 strains of Salmonella typhi-murium from two different regions of West-Germany were investigated according to their biotype and phagetype. 132 strains were isolated from sewage, 320 strains from animals and the others from human beings. 60 different phagetypes were found. The phagetype 49 occurred most often (11,9% resp. 10,3%). A correlation between biotype and phagetype could not be observed. Nearly every phagetype could be divided into several biotypes. However, only few biotypes prevaled. These comprised the biotypes 1, 10 and 17. The examination of the splitting of trehalose was useful in the biochemical differentiation. Concerning strains of animal origin it was remarkable that most strains from cattle resp. calves belonged to the phagetype 49. Among 145 strains from pigeons 95,9% could be classified as phagetype 2. With exception of 3 strains all the other strains from pigeons did not possess the O-antigen 5. The majority of the strains belonged to the biotype 8. All these strains could not split maltose.

Animals↗