ISSN:
1432-0878
Keywords:
Diencephalon
;
Monoaminergic tracts
;
Pars intermedia, Rana temporaria
;
Microspectrofluorimetry
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary With the fluorescence technique of Falck-Hillarp two monoaminergic tracts having independent nuclear sources, and extending towards the hypophysis, were identified in the diencephalon of Rana temporaria. The nature of the fluorophore in the diencephalic nuclei which give rise to the tracts, and also that of the nerve fibers innervating the pars intermedia (PI), were analyzed microspectrofluorimetrically. The first tract, the preoptic recess organ (PRO)-hypophysial tract, arises from the neurons of the PRO, traverses the preoptic region, ascends towards the dorsal chiasmatic area, curves down and extends posteriorly along the mid-ventral region of the tuber cinereum towards the median eminence. Apparently this pathway has no contact with either the paraventricular organ (PVO) or the nucleus infundibularis dorsalis (NID). The second pathway, the paraventricular organ (PVO)-hypophysial tract, arises mainly from the PVO of each side, traverses the tuber cinereum and converges posteriorly to join the PRO-hypophysial tract at the hind end of the tuber cinereum. Participation of the NID neurons in the formation of this tract could not be excluded. It is argued that the PVO-hypophysial tract, but not the PRO-hypophysial tract which runs along the mid-ventral region of the tuber cinereum, may be responsible for transportation of the monoamines from the PVO/NID to the pars intermedia. Microspectrofluorimetric study indicated that the PRO neurons contain only dopamine, whereas two types of neuronal fluorophores were observed in the PVO and NID. Many perikarya in both these nuclear sites possess dopamine, while some contain 5-hydroxytryptamine (5HT) and/or 5-hydroxytryptophane (5HTP). An analysis of the fluorescent nerve fibers in the PI revealed a double innervation. The first category includes dopaminergic fibers, whereas the second type seems to be adrenergic or noradrenergic in nature. On leave from the Department of Zoology, Nagpur University, Nagpur, India.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00222031
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