Expression of neuron-specific enolase in the pineal organ of the domestic fowl during post-hatching development.
Immunohistochemistry for neuron-specific enolase (NSE) revealed that NSE is localized in both a limited number of pinealocytes and intrinsic afferent neurons in the pineal organ of the domestic fowl. Furthermore, a computer-assisted three-dimensional imaging technique allowed to clarify the reverse distributional pattern of both elements: NSE-positive pinealocytes displayed a dense distribution especially in the vesicular portion of the gland, whereas NSE-immunoreactive nerve cells were mainly found in the pineal stalk. The number of NSE-positive intrinsic neurons in the pineal organ of chickens decreased rapidly after hatching, with a concentration of these elements in the basal portion (stalk) of the pineal organ. On the other hand, immunoreactive pinealocytes increased remarkably in the end-vesicle of the organ with age, followed by a gradual expansion toward the proximal portion. Thus, the spectacular increase in NSE-positive pinealocytes and the progressive reduction of reactive neurons occurred in parallel during the course of post-hatching development. NSE-immunoreactive pinealocytes displayed morphological characteristics of bipolar elements, endowed with an apical protrusion into the pineal lumen and a short basal process at younger stages, whereas multipolar types of NSE-positive pinealocytes were predominantly found in the adult domestic fowl. These results indicate that in the pineal organ of the domestic fowl (1) the ontogenetic expansion of NSE-immunoreactive pinealocytes is paralleled by a regressive afferent innervation, (2) the NSE-positive pinealocytes transform from a bipolar (columnar) type to a multipolar type during post-hatching development, and (3) these ontogenetic changes in the NSE-immunoreactivity and morphology of pinealocytes may reflect the development of a neurosecretory-like capacity of the organ.
Sato
T
T
Department of Anatomy, School of Medicine, Tokyo Medical and Dental University, Japan.
Kaneko
M
M
Ekataksin
W
W
Wake
K
K
D000818:Animals; D002645:Chickens / Q000254:growth & development / Q000378:metabolism*; D004790:Enzyme Induction; D015151:Immunoblotting; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D009475:Neurons, Afferent / Q000201:enzymology*; D010751:Phosphopyruvate Hydratase / Q000096:biosynthesis*; D010870:Pineal Gland / Q000166:cytology / Q000201:enzymology* / Q000254:growth & development
D009419:Nerve Tissue Proteins; D010751:Phosphopyruvate Hydratase