Cytological effects of urecholine stimulation on the rat pancreas

Summary Stimulation of the exocrine pancreas by the secretagogue urecholine causes degranulation of the acinar cells. Under in vivo conditions, this degranulation is not uniform throughout the tissue. Indeed some of the acini are almost completely depleted of their granules while others display the appearance of resting acini. A noticeable feature is that all the cells of the same acinus display a comparable degree of degranulation. Moreover, groups of neighbouring acini seem to respond simultaneously suggesting that the secretory stimulus is propagated from one acinus to the other. In vitro stimulation of dispersed acini also showed that some of the acini are more responsive than others indicating that this phenomenon can not be attributed to accessibility of the secretagogue to its receptor. These observations lead us to the concept that the response of the pancreatic acinar cell is controlled at the level of the acinus.