Embedding prolene for the development of fiducial markers

A simple, inexpensive method is described for embedding Prolene with tissue samples to provide landmarks for fiducial points to align serial sections in tissue reconstructions. Prolene is a monofilament suture material that can be easily sectioned with diamond knives to provide circular markers in each section. The sections are photographed, the negatives are projected through an enlarger and the contours, Prolene circles, and scratches from the diamond knife are traced onto paper. These landmarks establish a framework for assigning fiducial points that are necessary for the correct alignment of the contours. No special equipment is needed for embedding the Prolene and the method is adaptable for both automated and nonautomated computer systems. An example of this method for tissue alignment is given using embryonic limb tissue to determine the spatial organization of developing blood vessels as demonstrated by computer reconstruction.