Polyvinylchloride (PVC) particles implantation in mouse liver. A technique for experimental study of schistosome eggs-induced liver pathology.

An injection of suspended PVC particles in the caecal vein of mice induces a foreign-body portal granuloma reaction in the liver. Plastic casts of the portal system, after PVC particles implantation, show modifications in the portal bed and are compared with plastic casts obtained in mice infested by Schistosoma mansoni. This technique can be useful to study the cellular dynamics of the portal granuloma and can be a model for schistosomal eggs induced liver pathology.

[Definition of the organell concept].

Since the essential cytological functions are endergonic processes, the organelle cannot be defind without considering the necessary energy transfer. Therefore, a sensible definition may read: The Organelle is a cytoplasmatic structure capable of funtional energy consumption (Frey-Wyssling 1977).

[The scientific work of W. J. Schmidt (author's transl)].

Ten examples from W. J. Schmidt's workshop illustrate the method of ultrastructural research before the advent of the electron microscope.

Isolation of glucanase-containing particles from budding Saccharomyces cerevisiae.

In an investigation of the role of glucanases in modifying yeast cell walls at the location of new buds, vesicles derived from the endoplasmic reticulum, which are secreted locally into the cell wall of growing buds and may be involved in the secretion of glucanases, have been isolated.In yeast, exo-beta-1,3-glucanase (EC 3.2.

A new freezing-ultramicrotome.

The difficulties in sectioning frozen biological objects for electron microscopic investigations are overcome by Steere's freezing-etching method. In order to test this method and to open up a wide field of application, the new freezing-ultramicrotome has been designed. The apparatus consists of the combination of an ultramicrotome with freezing-drying and shadow-casting installations in the same vacuum container.

Stained pectin as seen in the electron microscope.

This paper describes electron microscopic studies on the distribution of pectin within young plant cells. Dark-grown onion roots, from 1 to 3 mm. in length, were used.

[Development and structure of proplastids].

In this study the proplastid development in embryonic cells is described for the apical meristem of , embryo sacs from , and leaf buds. The formation of these cell organelles originates with submicroscopical particles which consist of a homogeneous stroma with a surrounding double membrane. When these proplastids reach an average size of 1 µ, the inner layer of the membrane begins to invaginate into the stroma.