Crystal-like Inclusions Research Articles

Electron microscopic studies on the mammalian blastocyst in the pre-implantation stages.

This work was designed to investigate the fine structures of the rat and the rabbit blastocysts with both transmission and scanning electron microscopes.The cells of the trophoblast form a single layer beneath the intact zona pellucida and the inner cell mass and blastocystic cavity are formed. In the blastocyst on day 5 to 6 of pregnancy, the trophoblast cells were differentiated from the inner cell mass cells. However, the difference in density was not distinct and the distribution and structures of the organelles were almost similar in both cells.The tight junctional complex between the trophoblast cells and the loose association among the inner cell mass cells were observed. The organelles of the blastocysts were quite specific. In the rabbit blastocyst, as inclusions restricted to the blastocyst stage, crystal-like inclusions were present.From the standpoint of functional aspects the incorporation of 3H-uridine and 3H-thymidine into rat blastocysts was studied using electron microscopical radioautography. The result showed that incorporated 3H-uridine was found in all regions and 3H-thymidine mostly in nucleus. Moreover, with scanning electron microscope the surface of blastocyst was observed after the zona pellucida was removed with pronase. The surface of zona-free rat blastocyst was wholly covered with dense, fine microvilli and abembryonic proliferation was seen. Each bulging trophoblast cell was bounded by grooves and distinguishable to one another.

Electron microscopy of pokeweed leaf cells infected with pokeweed mosaic virus

Cytoplasmic inclusions associated with pokeweed mosaic virus (PMV) infection are similar to those which have been reported for other long, flexuous rod-shaped viruses. Cylindrical inclusions and their derivatives such as circular inclusions, tubes, laminated aggregates, bundles, and pinwheels are all associated with PMV infection. A close association between endoplasmic reticulum and both laminated aggregates and bundles was noted. Virus particles were not associated with virus-induced cytoplasmic inclusions but were evident in masses in the cytoplasm near the central vacuole. Near the accumulation of virus particles were many vesicles in various sizes. Golgi apparatus were closely associated with the vesicles. Many secondary vacuoles protruded into the central vacuole. The thin layers of cytoplasm surrounding secondary vacuoles were filled with virus particles. Stellate, crystallike inclusions were noted in chloroplasts of infected cells and apparently were not viral in nature. Cytoplasmic invaginations containing mitochondria or endoplasmic reticulum in chloroplasts of infected cells were noted.

The ultrastructure of erythroblastic islands and reticular cells in mouse bone marrow

An ultrastructural study of normal mouse erythroblastic islands and reticular cells has been made. Fixation in glutaraldehyde, then postosmication followed by double staining in uranyl acetate and lead monoxide has been found to greatly facilitate the classification of developing erythroblasts. Morphologic evidence for ferritin transfer from reticular cells to erythroblasts was not obtained. The prime function of the reticular cell is considered to be erythrophagocytosis. An unusual cytoplasmic feature of these cells are crystal-like inclusions which have not been noted in erythrophagocytes of other species. These structures are either completely or partially surrounded by single membranes and, in some instances, by elaborate multilaminated membrane systems. Although the chemical nature of the inclusions is unknown, their association with aggregates of ferritin and hemosiderin suggest they are some component of ingested erythrocytes. Other aspects of the ultrastructure of normal mouse marrow reticular cells have been described.

CYTOLOGICAL AND CYTOCHEMICAL STUDIES OF HELA CELLS INFECTED WITH ADENOVIRUSES

The sequential morphological and cytochemical alterations in HeLa cells infected with adenovirus types 1 to 4 are described. Each of the four viruses studied led to consistent and reproducible cytological changes not observed in uninfected control cultures. All four agents produced striking and characteristic changes in the nuclei of infected cells. Alterations in the cytoplasm, though present, were less marked, particularly in the early stages of infection. In cells infected with type 1 or 2 adenovirus, rounded intranuclear inclusions which progressed from eosinophilic and Feulgen-negative to basophilic and Feulgen-positive, together with a homogeneous glassy, Feulgen-positive nuclear background, were prominent features. Cells infected with type 3 or 4 adenovirus exhibited marked rearrangement of basophilic nuclear material and sharply defined crystal-like inclusions, predominantly intranuclear in location, which also varied from Feulgen-negative to positive. In terms of detailed cytological effects, therefore, the four agents could be divided into two subgroups, viz., types 1 and 2 on the one hand and types 3 and 4 on the other. Measurement of DNA in individual nuclei by means of Feulgen microspectrophotometry revealed the values in infected cells to be increased above the levels of the uninfected controls.