Effects of L‐azetidine‐2‐carboxylic acid on matrix secretion and Golgi structure in fibroblasts and osteoblasts of the mouse

The effect of a proline analogue, L‐azetidine‐2‐carboxylic acid (LACA), on collagenous matrix secretion by periodontal ligament fibroblasts and alveolar bone osteoblasts was studied by light and electron microscopic radioautography after injection of ³H‐glycine; ³H‐glycine labeled material accumulated in the cisternae of the rough endoplasmic reticulum and was not secreted for over 4 hours. The Golgi complex of both fibroblasts and osteoblasts showed a marked alteration of its composition after LACA administration. All Golgi saccules and collagen secretion granules disappeared within 2 hours. Flattened Golgi cisternae were still present and appeared to be unaffected by the administration of LACA. These observations indicate that Golgi saccules in collagen‐secreting cells are the initial staging areas for the formation of collagen secretory granules and that there is a close correlation between form and function in the Golgi apparatus of collagensecreting cells.