Is the avian glycogen body a secretory organ?

In the present study we have observed with the electron microscope the glycogen body of the chick, Gallus domesticus, which constitutes a spinal cord circumventricular organ specific of birds. We have detected in young chickens and embryos the presence of considerable amounts of glycogen particles in the cerebrospinal and vascular compartments, coming from the glycogen body cells, which are able to discharge part of their glycogen into either the central canal or the capillary lumen, via ependymal and endothelial cells respectively. If this secretion is a physiological condition, we propose that the glycogen body would play a role in the maintenance of the hydric and glucose haemostasia in the central nervous system, as well as in the osmoregulation.