A Micrurgical Method for Preparation of Chromosomes for Electron Microscopy

Abstract

Mammalian cells on coverslips in vitro are used during logarithmic growth phase to obtain many cells in mitosis without the use of mitotic inhibitors.Two short lengths of glass tubing attached by beeswax to a standard microscope slide provide support for the coverslip. The coverslip is placed cell side down to form a chamber with open ends for admission of microneedles and for changing the fluid environment of the cells. This open ended chamber is then filled with a physiologic salt solution such as Hanks or a growth medium such as Eagles.Microneedles governed by deFonbrune micromanipulators are admitted through the open ends of the chamber. A cell in metaphase is located, picked up by microneedle, and carried to a clear area on the coverslip (Fig. 1). The second microneedle may hold the cell while the first is moved sidewise to create an incision in the cell membrane through which the mitotic apparatus may egress.