Abstract
This paper describes a recently developed apparatus and technic for rapidlly cutting undecalcified bone sections sufficiently thin for microscopic and autoradiographic study. This technic is particularly applicable to the sectioning olf lold, dried bone or bone from mature animals. Sections may be cut at the rate of 20 to 40 per hour anld they may be cut serially with the loss of not more than 150 microns of material between sections.
I. The Sectioning Apparatus. A conventional brain microtome was adapted by substitutling a rotary, motor dtriven saw blade for the stationary knife blade. The bone to be sectioned was clamped in thte reciprocating carriage which fed the bone to the saw. The motor used in this apparatus is a “war surplus” item† designed to drive a rotary switch in aircraft. Its small size (2½ inchtes × 1½ inches diameter) and the rigid ball bearing mounting of the armature are highly desirable features. However, other designs of motors would no doublt be usable provided the armature end-play was eliminated. The motor is mounlted on a solid steel bar mahind to fit the knife blade clamps on the chhassis of the microtome. These clamps are adjustable so that rotation of the motor about an horizontal axis perpendicular to the path of the bone is possible. This permits a fine adjustment of the angle of attack of the saw blade, prevenlting it from cutting out of or into the bone as the section is cut. Figure 1 is a close-up photograph of the essential features of the apparatus. The circular saw bladest (commercially available for use in motur driven hand tools) are approximately 7/8 inch in diameter, have 88 teeth without set and are 150 microns thick.
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