Ultrastructure of leiomyoma of the ciliary body

Leiomyoma of the ciliary body of the eye was studied with the help of optical microscope at the ultrastructural level. The tumour was characterized by 4 types of cells: micro immature myoblasts, macro differentiated myoblasts, dystrophically changed muscle cells with lipofuscin inclusions, and fibroblasto-like cells. At the luminous level the differentiation of pigmental granules of melanin and lipifuscin was impeded. At the ultrastructural level they had different morphology, and therefore the differential diagnosis of a slightly pigmented melanoma and leiomyoma is possible.     

Functional alterations of cardiac subcellular structures during energy deficiency in relation to the metabolic state of the heart muscle cell

The functional behaviour of membrane systems of the cardiac cell during oxygen deficiency was analyzed and the alterations were related to the metabolic state of the tissue as an index of injury. 1. The retention function of the cell membrane for proteins. With increasing energy deficiency the cardiac sarcolemma loses its ability to retain macromolecules (myoglobin, enzymes) within the cell. Close correlations exist between protein release and oxygen supply as well as ATP content of the tissue. 2. Function of isolated mitochondria after ischemia. In parallel with a strong impairment of oxidative phosphorylation (decrease of QO2, RCI values, phosphorylation rates) the Ca++-transporting activity of mitochondria is continuously depressed with decreasing myocardial ATP. 3. Function of isolated sarcoplasmic reticulum after ischemia. With breakdown of high energy phosphates during ischemia rate and extent of Ca++ binding with decrease markedly.     

Incorporation of tritiated cytochalasin B into ectodermal explants of the amphibian gastrula

Ectodermal explants from gastrulae of Triturus alpestris were exposed to tritiated cytochalasin B (5 and 10 mug/ml) for 1/2-2 1/2 h. The flat explants failed to heal into compact spheres and the component cells gradually rounded up. Radioactivity in the fixed and sectioned material was analysed by light and electron microscopic autoradiography. Silver grains were found predominantly over the yolk platelets, but were also scattered over other cellular components. Areas containing pigment granules or the feltwork material, present in the apices of dissociating cells of the superficial layer, exhibited higher activity than areas containing mitochondria or cytoplasmic matrix. Lipid droplets and nuclei showed comparatively little activity. The results are discussed in relation to previous findings on the uptake of tritiated cytochalasin D by cell fractions.