Ultrastructural modifications at uterine cervix level induced by human papillomaviruses infections.

The paper presents the ultrastructural modifications occurring in uterine cervix epithelium in 10 patients with clinical susceptibility of HPV infections. The presence of viral HPV particles was identified in 5 cases and in 1 case the concomitant presence of both HPV and HSV2 particles was detected. The maximum amount of HPV virions is found in the spinous and superficial layer, particularly in the nucleus, but also in cytoplasm. In all the studied cases, cellular alterations were present in the whole depth of the epithelium. The degree of cellular alterations depends upon the epithelial layer to which they belong and to the stage of the disease as well. Cellular alterations are more pronounced at the level of the spinous and superficial layer being present both in nucleus (chromatin condensations, invaginations of the nuclear membrane, the occurrence of some pseudonuclei) and cytoplasm (intracytoplasmic vacuolizations, the presence of some inclusions). The presence of some giant mono- and binucleated cells as well as the formation of cellular syncytia in case of severe alterations are also reported.

Interactions between Borrelia burgdorferi and eukaryote cells: comparative ultrastructural aspects.

In the present study, mammalian VERO cells, human polymorphonuclear leukocytes (PMN) and mouse peritoneal macrophages (MPM) were coincubated with B31 Borrelia burgdorferi strain (Bb) and examined by transmission electron microscopy. The results indicate that the spirochete adheres to the mammalian cells mainly by the apical pole and less frequently by the lateral wall. In VERO cells and MPM cell penetration is accomplished especially by cytoplasmic membrane destruction, the spirochete appearing free in the cytoplasm, but also by phagocytosis. In this latter case the pathogen is seen in phagosome. In PMN the internalization takes place exclusively by phagocytosis, the spirochete undergoing destruction in phagosomes. Sometimes an alteration of the phagosomal membrane is observable, probably produced by the pathogen as a mechanism to avoid fusion with the lysosome. Other aspects indicate the contribution of the parasitized cell cytoskeleton to the spreading of Borrelia to adjacent cells. MPM does not represent a very efficient barrier against Bb, as can be seen from the cellular behaviour of the spirochetes in this study, PMN seems to a more efficient barrier, by its unique capacity to destroy the microorganism after phagocytosis.