title: Influence of photoperiod on dense-core vesicles and synaptic ribbons of pinealocytes of the djungarian hamster (Phodopus sungorus).
abstract: The ultrastructure of the superficial part of the pineal gland of Phodopus sungorus was examined. Dense-core vesicles and synaptic ribbons in pinealocytes of animals kept under different photoperiods were counted, revealing marked differences. Pinealocytes of short-day animals compared with long-day animals exhibit an increase of dense-core vesicles coincident with a decrease of synaptic ribbons. It is assumed that the corresponding numerical changes of these organelles are of functional significance in relation to pineal secretory activity.
mesh_terms: D000818:Animals; D006224:Cricetinae; D008027:Light; D008297:Male; D008855:Microscopy, Electron, Scanning; D010507:Periodicity; D010870:Pineal Gland / Q000648:ultrastructure*; D013569:Synapses / Q000648:ultrastructure*; D013572:Synaptic Vesicles / Q000648:ultrastructure