The Fibrin Clot; A Medium for Supporting Loose Cells and Delicate Structures During Processing for Microscopy

Abstract

Fibrin clots were used for suspensions; fibrin films for preserving in situ characteristics of conidial chains, delicate fruiting structures, and cellular arrangements of mycetozoa and fungi. A solution containing fibrinogen, 300–350 mg; Na-citrate, 160 mg; and NaCl, 850 mg per 100 ml, was mixed immediately before use, and in the amount needed, with an equal volume of a thrombin solution containing 5–10 units/0.l ml of sterile glass-distilled water. In these proportions, a clot formed within 20–30 sec. Washed suspensions, pelleted by centrifugation, were incorporated into the forming clot by twisting a sharpened applicator stick, first in an overlying activated fibrinogen solution, and then into the pellet until the cell mass was entrapped. Films were prepared either by spreading the activated solution on a coverslip onto which a piece of natural substratum or of agar bearing the desired structures was impressed, or by dropping the activated solution directly on the structures' support.