Intramitochondrial lamellar formations induced by pregnenolone-16- -carbonitrile in the hepatocytes of pregnant rats

The presence of hepatic intramitochondrial crystalline inclusions in polybrominated biphenyl-treated mice

Electron microscopic study of livers from mice fed 167 ppm polybrominated biphenyl (PBB) revealed mitochondrial abnormalities which consisted of both alterations in size and the formation of crystalline-like inclusions within the mitochondrial matrix. These inclusions appeared as parallel arrays of rods and were found in elongated mitochondria which contained few cristae. The findings are briefly described and the possible significance of such inclusions in relation to mitochondrial aberrations are discussed.

Intramitochondrial rod-like inclusions in human breast tumors

Ultrastructural screening of human breast tumor biopsies has revealed, in 43% of the carcinomas, and in 16% of the benign lesions examined. the presence of rod-like inclusions in mitochondria of epithelial cells. The inclusions are cylindrical in cross section, with a diameter of about 50 nm, and show regular striations in longitudinal sections. They are probably derived from cristae. Mitochondria with inclusions are usually enlarged and are found most frequently in epithelial cells of invasive tumors and near zones of tumor necrosis. Similar although not identical inclusions have been observed by other investigators in the liver of women with hydatidiform mole or choriocarcinoma, of pregnant women, and of women taking oral contraceptives. Identical inclusions have been found in mitochondria of HeLa cells treated with anti-HeLa serum. Although no clear-cut correlations were found between the finding of inclusions and parameters such as age of patients, nuclear grade or lymphocytic infiltration of the breast tumors, it is conceivable that the presence of mitochondrial inclusions reflects the effect of hormonal or of immunological factors.

Effects of anabolic steroids on liver cell ultrastructure in sheep

Castrated male sheep were sham inplanted or implanted with estradiol, trenbolone acetate or trenbolone acetate in combination with estradiol, and slaughtered after 56 days. Ultrastructural and morphometric examination of the livers of steroid-treated sheep showed an increase in the volume density of the cell occupied by rough endoplasmic reticulum and microbodies. In four of the eight sheep treated with trenbolone acetate, either alone or in combination with estradiol, enlarged mitochondria with crystalline inclusions were seen. The increase in hepatic rough endoplasmic reticulum may be of benefit to the sheep whereas the mitochondrial changes after anabolic steroid use indicate a cellular lesion of unknown significance for health.

Studies on the liver of Xenopus laevis. I. The ultrastructure of the parenchymal cell

The liver of Xenopus laevis was examined with electron microscopy. Its structure was found to be markedly different from that of mammals, particularly regarding the morphology of the hepatocytes to be classified as typical. It was established that the main function of such a cell is the storage of glycogen, and further that it possesses only scant organelles and other inclusions. Since this type of cell was found most frequently in the liver of untreated animals, it was designated as normal cell. The fact appears noteworthy that in the normal liver of Xenopus laevis an abundance of cell types occur which are otherwise found to be proliferated under experimental conditions, e.g. cells with pronouncedly augmented RER, enlarged Golgi complexes, increased lipid inclusions etc. This high number of divergent hepatocytes and the fact that all intermediate stages between the individual extremes are present and not to be accounted for by the position of the cell within the liver was interpreted as being the expression of a cyclic passage of the various stages of activity. It is of special interest that augmented degradation of glycogen in the liver cell takes place only during vitellogenesis. Acute and chronic hunger, as well as adaptation to cold, hardly affect the morphology of the normal cell, especially as far as the glycogen is concerned. The possible causes for this are discussed.

Studies on the progestational endometrium of the rabbit. II. Electron microscopy, day 0 to day 13 of gonadotrophin-induced pseudopregnancy

The fine structure of the endometrial epithelium of the pseudo-pregnant rabbit from the day of induced ovulation (day 0) to the 13th day is here correlated with previously defined light microscopic phases. In Phase 1 (0-1 day), in which there is a presumed "priming" of the endometrium by ovarian steroidal hormones, no changes were observed. In Phase 2 (1-3 days), in addition to mitotic activity, the epithelium showed a disappearance of the mucification and lymphocytic migration typical of Phase 1 and also of the non-pregnant or "estrous" phase, and showed other nuclear and cytoplasmic changes which probably reflect endogenous growth and protein synthesis. In Phase 3 (4-6 days), two distinct populations of reacting cells were present: (1) surface and cryptal cells investing the now folded mucosal surface, and (2) glandular cells. The first group showed characteristic dome-like protrusions of the cytoplasm into the lumen, and also showed distinct cytoplasmic and nuclear changes which appear to be a prelude to the succeeding phase of fusion but are not necessarily secretory in type. The glandular cells, in contrast, showed cytoplasmic changes which appear to reflect active secretory activity (hypertrophy of the Golgi area, cytoplasmic vacuoles containing electron-opaque material, etc.). This phase coincides with the maximal secretion of uterine-specific proteins, and electron-opaque material is abundant within the endometrial lumen. In Phase 4 (6-8 days), the surface and cryptal epithelium undergoes a transformation into multinucleated cells, the result of a process of lysis of intervening plasma membranes, the precise mechanism of which (i.e., with or without initial membrane fusion) was not determined. Cell fusion proceeded earlier and more actively mesometrially than antimesometrially. The glandular cells showed evidence of reduced secretory activity, but did not at any stage undergo multinucleate-cell transformation. In Phase 5 (8-13 days) there was progressive fusion, and the number of nuclei per cytoplasmic sac appeared increased, presumably due to the continued action of progesterone which is maximal during this phase. Glandular cells showed further reduced secretory activity but remained columnar. Ciliation of the epithelium was sporadic in the pre-secretory phases and rare or absent in the secretory and fusion phases; it became widespread during the phase of decline after day 14, a period which will not be included in this study. The fine structure of the ciliated cells was the same at all stages; there was no evidence for their origin from a reserve population; it is possible that they arise by modification of the multinucleated cells. Cytoplasmic crystals and intramitochondrial densities or lamellae were observed during the secretory and fusion stages, the former only in the glands, the latter in the surface and cryptal epithelium. They appear to be associated with rising or maximal progesterone secretion.