A transmission electron microscope study of fibroblast changes in human deciduous tooth pulp

The coronal pulps of four primary canines, free from radicular resorption, and of three primary teeth, with roots entirely resorbed, were prepared for electron microscopy. Mature fibroblasts, similar to those reported in the pulps of permanent teeth, were present in the pulps of the clinically mature teeth. Regression of fibroblasts, evident in the pulps of deciduous teeth at the root resorption stage, was characterized by cytoplasmic changes, modifications in the cytoskeleton and dissociation of cells and fibrils. Deciduous teeth might provide a model for studying pulp fibroblast ageing.

Enzymatic destruction of the elastic lamella at the mouth of cerebral berry aneurysm? An ultrastructural study with special regard to the elastic tissue

Destruction of the elastic tissue is probably an acquired lesion and is decisive for the appearance of cerebral arterial aneurysms at the sites of congenital media defects. The elastic component in the mouths of aneurysms has therefore been studied by electron microscopy, using two new staining methods, i.e. ruthenium-red staining and prolonged osmium-tetroxide treatment. The hypertrophic, duplicated, elastic lamellae showed a disintegration of their luminal portions not earlier described. In close connection with the disintegrated portions, extracellular lysosome-like granules were observed. It is hypothesized that discharged leucocyte grannules containing elastase help to destroy the elastic lamellae.

Collagenase: localization in polymorphonuclear leukocyte granules in the rabbit

Polymorphonuclear leukocyte granules were submitted to zonal fractionation through a discontinuous sucrose gradient. Azurophilic and specific granules were enzymatically characterized by peroxidase and alkaline phosphatase activity, respectively. The enzymes formed modal distributions like those reported by others. Collagenase activity was consistently associated with the specific granules containing alkaline phosphatase.