[The ultrastructure of the juxta-oral organ (author's transl)].

The ultrastructure of the juxta-oral organ has been investigated in the goldhamster. Its morphology was comparable to that already described in other species. Located in the cheek or in its anatomical homologue, the juxta-oral organ consists of a string of epithelial cells surrounded by two distinct layers. The first one, made of connective tissue, contains numerous terminal nerve fibres. The second one, external and separated from the first one by a fluid-filled space, is very similar to a perineurium. The juxta-oral organ of the goldhamster presented a new feature: its central string of parenchymatous cells always contained some nervous fibres. The parenchymatous cells were compared to the keratinocytes in the basal layers of the oral epithelium and the general structure of the juxta-oral organ to that of several mechanoreceptors. It is likely that the juxta-organ exerts a mechano-receptor function.