Paul Settlage

A simple method for preparation of gross brain sections.

The preparation of tissues for microscopic study of brain lesions is often a prohibitively expensive and time-consuming procedure. The authors have been using a technique for obtaining gross slices of the brain which are thin and uniformly sectioned, and which may be stained and photographed for permanent records. More than 50 brains (monkey, cat, human, and elephant) have been prepared by this method, and the material has been found suitable for use in published studies. The method does not prohibit subsequent preparation of tissues for microscopic analysis, but the adequacy of the anatomical check provided by a study of the gross slices may often eliminate the necessity for microscopic study. Of basic importance for the technique is the embedding mixture, the formula for which we first obtained from a mimeographed bulletin by Fisher and Garrett (1). This bulletin described a method of preparing and preserving slices of the human brain for teaching purposes (2). The present account is offered to illustrate the way in which the method has been adapted for research purposes, and for the sake of publishing some useful details of technique. The successive steps in the method follow.

A method of replacing portions of the calvarium with transparent plastic.

This research was supported in part by the University of Wisconsin Trust. Duz-All, the trade name of the plastic used in this series of experiments, is a patented preparation of Coralite Dental Products Co., Chicago, Illinois. It consists of a combination of methacrylie esters in powder and liquid form. A variety of methods has been employed for the purpose of permitting direct observation of pial vessels (1, 2, 3, 4, 5). Another method, differing in various ways from those used previously, is described in this paper. This method has been developed in monkeys, is a simple one, and does no apparent harm as far as the health of the animal is concerned. Although the efforts of the authors to date have been limited to the attempt to observe changes in cerebral vessels, it is felt that the plastic insertion may lend itself to other purposes, such as the installation of electrodes, thermocouples, or ventricular needles.