Herbert M. Dembitzer

The fine structure of staggerer cerebellum.

The cerebellar cortex of staggerer mice, ranging in age from 12 days to three months, was studied in the electron microscope. In general, the cerebellum showed a much delayed developmental pattern with regard to Purkinje cell spine formation. Spines did not appear on the soma until about 6 days after birth and appeared on the dendritic branchlets at only 23 days. Climbing fibers were present and they were in synaptic contact with both somatic and dendritic spines. By the third month, spines were only rarely observed and some of these were unattached to any presynaptic element.

The transverse bands as a means of access to the periaxonal space of the central myelinated nerve fiber.

The distribution of a tracer, lanthanum, in the brain was examined in the electron microscope both after implantation and after immersion of fixed small blocks. In both cases, the distribution was essentially the same. It was found in the extracellular spaces, between myelin lamellae, between the transverse bands at the nodes of Ranvier, and within the periaxonal space. It was concluded that the transverse bands consist of several, separate, parallel bands which, with their intervening spaces, trace a continuous helical path from the extracellular spaces at the nodes of Ranvier to the periaxonal spaces.

Epidermolysis bullosa hereditaria letalis. Pathology, natural history and therapy

A patient with epidermolysis bullosa hereditaria letalis had the characteristic electron microscopic lesions not only in the skin, but also in the gastro‐intestinal, genito‐urinary and respiratory tracts. Administration of dexamethasone to this patient resulted in a significant decrease in the blistering. Although the patient died, long term survival in this disease is not rare. We report that staining tissue specimens from patients with epidermolysis bullosa with fluorescein‐labelled bullous pemphigoid antibody is a reliable method for differentiating between junctional and dystrophic disease.

The Fine Structure of Astrocytes in the Adult Staggerer

The fine structure of the cerebella of staggerer mice was studied. Particular attention was paid to the astrocytic processes which showed characteristic changes in the adult animal. These consisted of parallel configurations of slender sheet-like astrocytic processes frequently connected to one another by highly organized intercellular adhesive devices. The abnormal condition seen in staggerer is an exaggerated expression of the fundamental tendency of the astrocyte to form sheet-like peripheral processes.

Observations on the development of the weaver mouse cerebellum

The cerebellar cortices of young weaver mice were examined by electron microscopy and compared with those of normal littermates. Unattached dendritic spines arising from Purkinje cells, very much like those previously described in the adult weaver, were found by the eleventh day after birth. Granule cell degeneration was seen but not examples of degeneration of presynaptic structures could be detected. Unlike either the adult weaver or the developing normal mouse, symmetrical junctions between dendritic spines were present, as were asymmetrical junctions between Purkinje cell dendritic spines and nonspecialized regions of the surface of external granule cell soma. The mechanism of formation of the unattached spines is discussed.

On the relationship between human and experimental granule cell type cerebellar degeneration.

The fine structural alterations in a case of granule cell type cerebellar degeneration were examined and compared with the fine structure of the murine mutant “weaver.” By means of both conventional processing and especially with the use of the phosphotungstie acid procedure, it was determined that the alterations in both the human disease and the murine mutant were morphologically similar. In both cases, granule cells were almost totally absent but unattached Purkinje cell dendritic spines were numerous and virtually indistinguishable from those found in the control tissue. On this basis, it is suggested that the weaver mouse may be useful as an experimental model for granule cell type cerebellar degeneration in humans. The use of the phosphotungstic acid technique on formalin-fixed tissue is discussed and its value for the examination of human pathological material is illustrated.

The periaxonal space in an experimental model of neuropathy" the mutant Syrian hamster with hindleg paralysis

SummaryThe periaxonal space of peripheral myelinated axons was studied in the mutant Syrian hamster with hindleg paralysis, an experimental model of neuropathy. Despite pronounced alterations of the axon and the surrounding sheath, sometimes leading to demyelination, the periaxonal space showed remarkable resistance to change in most instances. When the space was widened as the result of the infiltration of extracellular fluid, the axon was found at the periphery of the enlarged inner perimeter of the sheath. Even under these extreme conditions the axon maintained a close to normal distance from the inner collar of cytoplasm. The significance of these findings with regard to both the normal anatomical relationship within the sheath and to the mechanisms of demyelination are discussed.

The fine structure of phosphotungstic acid stained neuropathologic tissue

SummaryThe ethanolic phosphotungstic acid technique of Bloom and Aghajanian has been applied to formalin-fixed neuropathological specimens. The staining reactions of various normal organelles were studied as well as a number of pathological alterations including Alzheimer neurofibrillary tangles, eosinophilic rod-like structures, corpora amylacea, lamellar bodies and honeycomb-like structures in the axoplasm.