Ultrastructural changes associated with the inhibition of monocyte chemotaxis caused by products of axenically grown Entamoeba histolytica.

The supernatant fluid of axenically grown Entamoeba histolytica-HM1 significantly modifies the ultrastructural features associated with monocyte chemotaxis as assayed in Boyden chambers. This morphological evidence supports the existence of a factor, monocyte locomotion inhibitory factor (MLIF), produced by E. histolytica that inhibits the in vitro locomotion of human monocytes. None of the leucocyte-locomotion modifying drugs included in this study (i.e., cytochalasin-B, colchicine, vinblastine, and hydrocortisone) caused changes totally comparable with those induced by MLIF. The most striking feature was the increase of centriole-associated microtubules induced by MLIF and by cytochalasin-B. MLIF may inhibit monocyte locomotion by directly inducing excessive microtubule assembly, although a direct, if somewhat weak effect upon microfilaments cannot be excluded. The increase in microtubules could then represent a perhaps futile attempt of the microtubule organizing center to overcome the locomotion blockade that has occurred elsewhere in the cell. If active in vivo, MLIF may contribute to the paucity of inflammation in the advanced stages of invasive amebiasis, and consequently to the lack of scar tissue formation upon recovery from such lesions, as monocytes constitute an essential link to the healing process.

Immunological and ultrastructural study of the surface of isolated rat testis germinal cells.

In the present study, cross absorption tests and indirect immunofluorescence detected antigenic differences between isolated testicular cell populations from 21 and 38 day old rats, respectively. Qualitatively, spermatids were the only cell type difference between these populations. Spermatozoa from adult rats were also studied. Our findings suggest that spermatocytes, spermatids and spermatozoa shared on or more antigens; spermatids and spermatozoa seemed to share one or more antigens not observed in spermatocytes by indirect immunofluorescence. Various patterns of immunofluorescence were encountered, suggesting differences in amount and distribution of antigens among the cells studied. The supramolecular appearance of the surface of spermatocyte enriched populations and of spermatid enriched populations were compared by scanning electron microscopy (SEM) and no striking difference was observed between both cell populations.

Estudio inmunologico y ultraestructural de la superficie de celulas testiculares aisladas de rata. / Immunological and ultrastructural study of the surface of isolated rat testis germinal cells

En este estudio se informan diferencias antigenicas, evaluadas por absorcion cruzada e inmunofluorescencia indirecta, entre dos poblaciones de celulas testiculares aisladas de ratas inmaduras: una enriquecida en espermatocitos (71 por ciento). Nuestros hallazgos sugieren que los espermatozoides comparten uno o mas antigenos. Ademas, las espermatides y los espermatozoides tienen uno o mas antigenos que no se observaron por inmunofluorescencia en los espermatocitos. Se encontraron diferencias en la inmunofluorescencia que sugieren modificaciones en la cantidad y distribucion de los antigenos entre las celulas estudiadas. Por medio del microscopio electronico de barrido se estudio la apariencia supramolecular de la superficie de espermatides y de espermatocitos. No mostraron diferencias significativas entre si

[Ultramicroscopic study of the colonic mucosa infected by E. histolytica]. / Estudio ultramicroscópico de la invasión de la mucosa del colon por E. histolytica

In eight guinea pigs, trophozoites of E. histolytica HM-2 IMSS strain grown in plurixenic conditions were inoculated in their cecum. Two died two days after inoculation; the remaining si- were sacrificed six days afterwards. Tissue samples were obtained from amebic lesions and nearby areas. At ultramicroscopic level it was observed that epithelial cells in contact with the parasite had short and/or scanty microvilli, swollen mitochondria, ER dilatation and absence of the terminal bar. When trophozoite was within the epithelium, cells in contact with it were destroyed; basement membrane was elongated before it was broken up by the parasite. In the lamina propria trophozoites were found close to glands, blood capillaries and in contact with macrophages, lymphocytes, and most cells. No polymorphonuclear cells were identified in all samples studied. Capillaries were congestive, lacking polymorphonuclear cells. It was postulated that probably initial colonic mucosa lesion in amebiasis depends solely upon parasite action.