First evidence of holocrine secretory mechanism in granular ducts inmouse mandibular gland

The mouse mandibular gland contains granular ducts, which possess a particular structure. They are termed granular ducts because they contain numerous granules in the cells lining them, having a secretory activity. We aimed to assess the secretory mechanism in granular ducts. Consequently, we harvested the mandibular glands from five male mice and processed them for histological investigations. A large number of cells appeared intact, without obvious distortions or disruptions in the cell membrane. Based on the morphological aspect, these cells either transferred the secretory product through exocytosis or were in "standby" mode. There were cells that presented prominent bulges of the apical pole, thus suggesting an apocrine mechanism. Some cells presented discontinuities in the apical pole and a tendency of granule transfer towards the lumen. According to the morphological aspects, these cells eliminated the secretory product through a holocrine mechanism. The morphological aspects noticed in this study revealed that the release of secretory products in some cells lining the granular ducts in the mouse mandibular gland can also be achieved through a holocrine mechanism.