"Synaptic" ribbons and spherules of the rat pineal gland: day/night changes in vitro?
In the present study pineal glands of rats aged 69-71 days were studied in vivo and in vitro with respect to day/night changes of "synaptic" ribbons and spherules. It was found that ribbons outnumber spherules by a factor of 3. In vivo, both ribbons and spherules show a roughly 3-fold increase in number at 1 a.m. when compared to 1 p.m. Up to 39 h in vitro, the two structures in question did not reveal day/night differences in amount, suggesting that diurnal rhythmicity of the gland did apparently not persist in organ culture. After 3 h in organ culture, the spherules, but not the ribbons, showed a striking increase in number, showing that ribbons and spherules may be governed by different mechanisms.
D000818:Animals; D002940:Circadian Rhythm; D008297:Male; D008854:Microscopy, Electron; D010870:Pineal Gland / Q000033:anatomy & histology*; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000648:ultrastructure*; D013570:Synaptic Membranes / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000648:ultrastructure