Nuclear-Cytoplasmic Relationships in Human Cells in Tissue Culture

Several methods have been developed for in situ embedding of tissue culture cells grown on glass. Borysko and Sapranauskas (1) first reported a technic for embedding whole colonies of cells for sectioning in a plane perpendicular to the glass surface. Howatson and Almeida (2), using a modification of Gay's method for smears (3), embedded cells by inverting gelatin capsules, filled with partially polymerized methacrylate, over selected areas of the slide, producing blocks which could be sectioned parallel to the surface of the glass. The procedures described by Nebel and Minick (4) and by Bloom (5) allow more accurate orientation of capsules over specific cells, but are limited by their equipment to embedding only one field of cells at a time. Nishiura and Rangan (6) recently described a stand constructed for embedding multiple sites with some degree of specificity, and Lat ta (7) developed a method allowing selection of completely random sites for embedding cultures grown in Petri dishes. Studies by electron microscopy on the effects of enucleation on the morphologic structure of cytoplasm required modification of these methods to permit more flexible independent positioning of small capsules for simultaneous embedding of a number of randomly distributed single enucleate fragments. As many as 15 to 20 fragments can be produced in one culture vessel (8, 9), but for orientation in sectioning only 1 or 2 should be embedded per capsule. The technic described in this report utilizes No. 4 gelatin capsules and a magnetic mounting holder. I t allows rapid, accurate location and embedding of single cells or fragments in as many as eight capsules per culture.