An electron microscopy study of Legionella pneumophila after in vitro and in vivo culture.

The ultrastructure of Legionella pneumophila serogroup 1 (Philadelphia Strain) was studied by Scanning Transmission Electron Microscopy (STEM) following in vitro and in vivo culture. The results obtained were identical for all the samples tested; the structure belonged to the prokaryotic type, with features consistent with the known structure of Gram-negative rods. A characteristic feature is the loose undulated outer membrane, a peptidoglycan layer which was difficult to visualize and was better seen in lysed bacteria.

Immunolocalization of matricial components during the early stages of chick embryonic liver development.

In the chick embryo, the first liver primordium is observed at the end of the second day of incubation. At 3 and 4 days, ultrastructural analysis of the primitive vascular spaces showed that the endothelial limiting plate was constituted by one or several cell layers. At the vascular pole of the hepatoblasts, mesenchymal cells and connective matrix, present as fibrillar and non fibrillar components, were closely associated.

[Technique of inclusion in epoxy resin for alternative photonic and ultrastructural examination (author's transl)].

Fragmentation of the samples in small blocks for electron microscopy fail to allow topographic study. Therefore a method fod embedding large blocks in epon is detailed here. It provides large semi-thin sections for photomic examination and, after making a "mesa", ultrathin for ultrastructural study.