HETEROTOPIC BONE FORMATION

PARTICIPATION OF THE MESENCHYMAL SYSTEM

Abstract

The renal vessels of the rabbit were ligated and its subpelvis connective tissue was daily explored for the mesenchymal system with toluidin-blue test by Kramer and Windrum method, from the next day of the ligation to the 170th day.
The results obtained are as follows:
1) On the first day after the ligation, an infiltration by histocytes is seen in the connective tissue directly underlying the epithelium.
2) On the 5th day, β-metachromasia and numorous infiltrations by lymphocytes, eosinophilic leukocytes, histocytes and fibroblasts are observed in the subepithelial and sumbmascular connective tissues.
3) On the 9th day, the cells showing α-metachromasia become pronounced.
4) On the 10th day appear many phagocytes.
5) On the 20th day appear a number of foreign body giant cells, whereas ather cell infiltrations are on the decrease.
6) On the 30th day, a bone formation is recognized under the hyperplastic epithelium.
7) On the 35th day is seen a bone tissue with bone marrow capable of hematopoiesis.
8) On the 45th day, the bone tissue is extended to the medulla of the kidney.
From the facts above mentioned, it is presumed that it is not the mesenchymal remannts but the mesenchymal reaction under the epeithelium and the muscular layer of the renal pelvis, caused by ligation of the renal vessels, that plays a standing role in metaplasia of the bone.
It should be suggested here that heterotopia of a smooth muscle in the urinary tract after a plastic surgery on that region, which constitutes a smiliar condition to the foregoing experiment, may be attributed to the same mechanism.