ISSN:
1432-0878
Schlagwort(e):
Paraphysis cerebri
;
Histology
;
Cytochemistry
;
Electron microscopy
;
Autoradiography
;
Salmo gairdneri Richardson
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Medizin
Notizen:
Summary The paraphysis cerebri of adult Salmo gairdneri is represented by a differentiated part of the pars impar telencephali of the telencephalic roof. It consists of a vaulted epithelial sheet, which displays only a few rostral evaginations and separates the cerebrospinal fluid (CSF) from the meningeal interstitial fluid. The fenestrated, sinusoidal portal system surrounding the paraphyseal epithelium appears to be part of a complex vascular bed of the dorsal telencephalic and diencephalic area. Myelinated and unmyelinated nerve fibers observed in the vicinity of the paraphyseal epithelium fail to make synaptic contact with paraphyseal cells. The single-layered epithelium is composed of characteristic, rather small, optically dense, cuboidal and cylindrical cells, apically mutually attached by junctional complexes including zonulae occludentes. These paraphyseal cells execute a high energetic and a moderate synthetic metabolism as indicated by ultrastructural, cytochemical and enzyme-cytochemical observations. Morphological evidence is presented for a multiple function of these cells in the regulation of the CSF: 1) water and solute elaboration into the ventricular system, 2) restricted uptake of high molecular weight organic substances from the CSF, 3) restricted uptake of low molecular weight substances from the CSF, but apparently not of GABA and of biogenic amines, 4) the formation and pinching-off of “blebs” as expression of a physiological mechanism not yet elucidated. The possible relationship between the level of development of the paraphysis cerebri and the sensitivity of animals to hydro-mineral metabolism is discussed.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00225570
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