Quantitative changes in the numbers of dense-core vesicles and 'synaptic' ribbons in pinealocytes of the Djungarian hamster (Phodopus sungorus) following sympathectomy.

The dense-core vesicles and 'synaptic' ribbons were counted in Djungarian hamster pinealocytes after superior cervical ganglionectomy. Sympathectomy caused a decrease in the number of dense-core vesicles in pinealocytes, suggesting diminished secretory activity of these cells. An increase in the number of 'synaptic' ribbons after superior cervical ganglionectomy supports the hypothesis that adrenergic innervation of the pineal gland influences the level of 'synaptic' ribbon formation.