Comparative histology of the annular and cruciform pulleys.

Twenty annular and 12 cruciform pulleys were dissected from four unembalmed fresh cadaveric fingers and stained with haematoxylin and eosin, Verhoeff-van Gieson stain for elastin, alcian blue stain for hyaluronic acid, and a separate stain for S-100 to identify chondroid cells. Three distinct layers were identified in both annular and cruciform pulleys: an outer layer of fibrofatty tissue with vascular channels outermost, an inner layer of hyaluronic acid-secreting cells, and a collagen-rich layer in between. Chondroid metaplasia was noted in the inner layer of both types of pulleys. Minimal differences were noted in regard to the elastin fibre content of the pulleys, with slightly more elastin in the annular pulleys, but no other differences were noted.