[Oscillatory changes in cells of the submandibular glands in mice during the secretory cycle]

By means of 3H-leucine radioautography, ultrastructural and morphometrical analysis, it has been demonstrated that in the cells of the acinar (Ac) and granular (Gr) parts of the submandibular gland (SMG) in mice with a synchronized for 3 h nutrition cycle there are endogenic fluctuations (for about 1 h) of the secretory process. They are demonstrated as alterations in intensity of protein synthesis in the cells, their areas and ultrastructure. In the Ac cells at the moment of feeding and in 50, 110, 150 min after feeding maximal leucine incorporation is observed. The changes in the cell area during the first hour occurs with 10 minutes' overtake of the incorporation intensity, and during the following 2 h an equilibrium is reached between these two parameters, when the maximal contents of the label corresponds to the minimal area of the cells. In the Gr cells one maximum of 3H-leucine incorporation occurs in 60-80 min after feeding. The minimal content of the label takes place in 10 and 120 min after feeding. During the time mentioned inverse ratio between the intensity incorporation of the labelled isotope and the change of the cell volume is observed. This is connected with autoregulatory processes in the cells. It is possible that in the Ac cells together with removal of the secretory granules by means of exocytosis (in 10-20 min after feeding) the secretory material is removed before it is formed as granules by parvivesicular extrusion. In the Gr cells apocrinic and endocrinic secretion takes place. Presence of certain specific formations (secretory lysosomes) explains peculiarities of the secretory process in the SMG.