ISSN:
1432-0878
Keywords:
Subcommissural organ
;
Pineal organ
;
Innervation
;
Horseradish peroxidase (HRP)
;
Synaptoid contacts
;
Carassius auratus (Teleostei)
;
Rana perezi (Anura)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract The present study was designed to investigate the controversial subject of the existence of a neural input from the pineal organ via the pineal tract to the subcommissural organ (SCO) in teleosts and anurans. Horseradish peroxidase was injected into the pineal organ and pineal tract of Carassius auratus and Rana perezi. Within the pinealofugal fibers the tracer was visualized at the light-and electron-microscopic levels either by immunocytochemistry using an anti-peroxidase serum, or by revealing the enzymatic activity of peroxidase. In both species, labeled myelinated and unmyelinated fibers of the pineal tract were readily traced by means of electron microscopy. In R. perezi, numerous terminals contacting the SCO cells in a synapse-like (synaptoid, hemisynaptic) manner bore the label, whereas a different population of endings was devoid of the tracer, indicating that in this species the SCO receives a dual neural input, one of pineal origin, the other of unknown source and nature. In the SCO of C. auratus, neither labeled nor unlabeled synapse-like contacts were found. Thus, in this latter species, a direct neural input to the SCO is missing. It is concluded that the secretory activity of the SCO can be controlled by different mechanisms in different species, and that more than one neural input mechanism may operate in the same species.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00312834
Permalink
