ISSN:
1432-0878
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Paraphyses from the brains of adult Triturus pyrrhogaster and adult and larval Taricha torosa have been examined by light and electron microscopy. Adjacent epithelial cells of the CSF-filled paraphyseal saccules are partially separated by extensive intercellular compartments containing variable amounts of granular, electron dense material. Each compartment is open basally against the basement membrane but narrows apically to a tight junction. Finger-like projections of neighboring cells interdigitate across the compartments. Toward the apical surface of the epithelium, the interdigitations are attached to each other by numerous desmosomes. The interdigitations and basal infoldings of the plasma membrane impart a paraphyseal morphology resembling cells known to be involved in fluid transport. Luminal surfaces often bulge and are microvillous near tight junctions. A single cilium is common. Interior cytoplasmic components include scattered mitochondria, smooth and rough endoplasmic reticulum, Golgi complexes, basal lipid accumulations, and variable amounts of glycogen granules. External to the epithelial cells, unmyelinated nerve bundles course through the connective tissue separating the epithelium from the underlying venous sinusoidal network. Presumed mast cells are present in the connective tissue in addition to fibroblasts. Thorotrast particles (colloidal thorium dioxide) introduced into the venous sinusoids rapidly traverse the endothelium and accumulate at the basement membrane of the paraphyseal epithelium. After two hours, the smallest particles of the tracer suspension have penetrated the basement membrane and are found scattered through the length of the intercellular compartments. Thorotrast neither invades cytoplasmic components of the epithelium nor crosses tight junctions to enter the CSF, even when the particles circulate for as long as nine hours before fixation. These findings are discussed in relation to previous light microscopical examinations and theories on possible paraphysis function.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00323310
