Lysosomal Residual Bodies Research Articles

Extracellular and transcellular transport of horseradish peroxidase (HRP) through the hypothalamic tanycyte ependyma.

Penetration of the median eminence and ventrolateral walls of the III ventricle by intraventricularly injected horseradish peroxidase was studied in rats. Experimental times varied between 10 to 70 min (short-term experiments) and 12 hrs to 30 days (long-term experiments). In short-term experiments, the median eminence was found to be completely stained whereas the lateral walls of the III ventricle were penetrated only up to 1 mm in depth. Spreading of the tracer takes place predominantly through the extracellular space and cellular uptake and transport do not seem to play a role during the first 70 min following the injection. In long-term experiments, the tanycytes exhibit a variety of intracellular inclusions marked by HRP precipitate. Tanycytic perikarya contain dense bodies and lipofuscin-like aggregates. Lipoprotein granules are thought to arise from these and are interpreted as lysosomal residual bodies. In tanycytic processes and perivascular endfeet, accumulations of HRP-containing tubules and polymorphous granules are encountered suggesting a transport towards the blood vessels of the portal plexus or of the arcuate and ventromedial areas, respectively. Sporadic tanycytes which are completely and evenly stained from the ventricular surface to the end of their processes were observed in the arcuate and ventromedial area. Whether this appearance can be taken as a sign of normal cell function seems doubtful. Some possible routes of transport through the median eminence—extracellular and transcellular—are summarized in a schematic drawing, taking into account the present findings and those published elsewhere in the literature.

Der juxtaglomeruläre Apparat der Rattenniere im Verlauf von Wachstum, Reifung und Alterung

The juxtaglomerular granulation index (the specific secretory ability of the vas afferens wall-cells) in the healthy unstressed rat shows age-specific quantitative, qualitative and topographic changes. These changes are motivated by cellular and functional, renal and extrarenal factors. At birth there are a few granules in the polar region of the more developed juxtamedullar glomerula, sparing the remaining cortex zones. After 20 days the production of secretion granules reaches its peak. Thereafter the granulation index gradually decreases and fluctuates towards the normal values of the adult rat. From the 3d to the 18th month it remains constant. Thereafter the ageing-process sets in : insufficiency in synthesis, in transport and in cell-division and specially a disturbance of cellmembrane-permeability. Further there is a reduction in the absorption ability of the with lysosomal residual bodies overloaded tubular epithelial cells. The juxtaglomerular granulation index is reduced to levels comparable to the newborn. The pattern of distribution differs during growth, maturation and ageing. The age specific changes of the granulated epitheloid cells correlate with those of the macula densa.

Liver cell defaecation: an electron-microscope study of the discharge of lysosomal residual bodies into the intercellular space.

Liver cell defaecation: an electron-microscope study of the discharge of lysosomal residual bodies into the intercellular space.

The occurrence of specific cytoplasmic granules in the osteoclast

The structure of the osteoclast in the tibiofemoral epiphyses of fetal rats has been studied by electron microscopy. The findings demonstrate the existence of dense specific granules which are apparently isomorphic with the primary lysosomes of soft tissue cell types. Points of morphological analogy include: an agranular unit membrane, a finely granular matrix, and a variable range of size and density. In further analogy, the specific granules also appear to be derived directly from the Golgi apparatus. The formed specific granules are localized in the cytoplasm subjacent to the ruffled border. At this site they undergo an apparent cyclic variation in numbers during which individual granules may undergo alternate transformations into cytoplasmic vacuoles or complex multivesicular and lamellated bodies identifiable with lysosomal residual bodies. Consideration of these morphological findings, along with recent cytochemical studies on the distribution of enzymatic activity in bone cell fractions, would seem to provide some further evidence that the underlying basis of the function of the osteoclast in bone resorption may involve an enzymatic mechanism.