Abstract
“Synaptic” ribbons (SR) are functionally enigmatic organelles characteristic of a number of neuroreceptor cells including the mammalian pinealocyte. SR appear to be responsive to a number of physiological stimuli, both normal and experimental. During the first days after birth, an initial, non-rhythmic rise in SR numbers nocturnally and diurnally (King and Dougherty, 1980) appeared to reflect a similar non-rhythmic increase in norepinephrine (NE) content in the neonatal rat (Moore and Smith, 1969). During the second postnatal week, both SR numbers (fig. 1) and NE content developed circadian rhythms, being high nocturnally and low diurnally. Our observations suggested that the circadian rhythm in SR numbers is regulated or influenced directly by an adrenergic mechanism via the superior cervical ganglia. Morphometric analyses of SR populations in female rat pinealocytes were performed to determine changes related to (1) continuous light, (2) continuous darkness, (3) isoproterenol, isoproterenol-propranolol and isoproterenol-phentolamine administration and (4) bilateral superior cervical ganglionectomy (SCGx) and SCGx-isoproterenol administration. Comparison of this data to that obtained from SR populations during the course of so-called “normal” 12 hours light:12 hours darkness cycles was made (fig. 2).
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Proceedings, annual meeting, Electron Microscopy Society of America
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
