Quantitative changes in number of "synaptic" ribbons in rat pinealocytes after orchidectomy and in organ culture.

A quantitative study of "synaptic" ribbons in rat pinealocytes was performed after orchidectomy and in organ culture. Both orchidectomy and culturing the pineal organ caused an increase in number and size of these structures. Present study indicate that microtubular sheaves and/or microtubules may represent precursors of "synaptic" ribbons. It is suggested that "synaptic" ribbons of rat pinealocytes, far from being phylogenetic relics of no functional significance play a role in the function of the pineal organ. An exact functional interpretation of the "synaptic" ribbons, however, is still a matter of conjecture.