David Cowen

Granular Cell Tumors of the Central Nervous System

This paper describes two cases of granular cell tumor, the first such tumors believed to have arisen in the central nervous system with the exception of those in the neurohypophysis. The tumor in one case arose in the cervical spinal leptomeninges and in the other was located in a cerebral hemisphere. The light and electron microscopic characteristics were indistinguishable from granular cell tumors (myoblastomas) reported in other body sites. Ultrastructurally two cell types could be distinguished. The predominant form (Type II) was characterized by abundant cytoplasm filled with dense bodies, multivesicular bodies and vacuoles. A second smaller cell (Type I) contained few of the above organelles. It is considered likely that these cell types are evolutionary stages of a single kind of a cell in which Type I is transformed into Type II. Various cells, including Schwann cells, have been proposed as giving rise to granular cell tumors. The occurrence of these neoplasms in the central nervous system lessens the likelihood of a Schwannian source in all instances. An origin from Schwann cells of perivascular nerves cannot be excluded. The possibility remains that neoplasms designated as granular cell tumors may have more than one cell of origin.

Phosphatase Histochemistry of Feline Cervical Spinal Cord after Brachial Plexectomy

A reticulum is demonstrable in perikaryon and dendrites of feline motoneurons by application of a histochemical technic for TPPase and NDPase activities. At the level of light microscopy this reticulum is separable from the basophil network of Nissl except that, in dendrites especially, lamellae derived from both structures appear, occasionally, to be in continuity or even identical. During axonal reaction the TPPase-, NDPase-positive reticulum recedes from the perinuclear area, especially opposite the axon, and migrates to the periphery. These changes, well-developed in the 15 to 30 day postoperative period, are followed by a restitution toward the normal appearance about 46 to 60 days after neurectomy. Regeneration of the reticulum appears to occur from both the cytoplasmic and nuclear membrane sides of the cytoplasm. The alternations encountered resemble those reported by earlier workers who applied classical technics for the Golgi apparatus to chromatolytic neurons. The network demonstrated by the enzyme histochemical method is equated with the Golgi organelle. Lysosomes, identified in Gomori acid phosphatase preparations, increase in numbers in chromatolytic neurons. In addition to the perikaryon, dendrites show a conspicuous increase in lysosomal content. This phenomenon is discussed. Possible developmental relations between lysosomes and other cell constituents are also discussed. Evidence, suggestive of a discharge of TPPAse- and NDPase-positive lamellae and lysosomes into axons during chromatolysis, is described. In TPPase and NDPase preparations there is a striking increase in glial activity in the anterior and posterior horns following plexectomy.

American Association of Neuropathologists

Office of Secretary-Treasurer Institute of Pathology Case Western Reserve University 2085 Adelbert Road Cleveland, Ohio 44106 Phone: 216-368-2488, Fax: 216-368-8964 Email: aanp@case.edu http://www.neuropath.org Officers Other Executive Council Members Bette K. DeMasters, President Jeffrey A. Golden Mark L. Cohen, Vice-President Michael N. Hart Barbara J. Crain, President-Elect Roger E. McLendon Thomas J. Montine, Vice-President-Elect Joseph E. Parisi Tarik Tihan, Vice-President for Professional Affairs Harry V. Vinters George Perry, Secretary-Treasurer Clayton A. Wiley Kevin A. Roth, Assistant Secretary-Treasurer

The melanoneurons of the human cerebellum (Nucleus pigmentosus cerebellaris) and homologues in the monkey

Little has been written about the cells here termed cerebellar melanoneurons. This paper describes and illustrates their cytologic features and topographic relationships. In the human brain these large pigmented neurons are scattered in a narrow layer near the lateral wall, dorsal angle and roof of the fourth ventricle. They form an inconspicuous part (group A4) of the system of catecholamine, neuromelanin-containing cells well known in the brain stem. Rostrally, a few of them provide a tenuous continuity with the locus ceruleus but topographically the two nuclei are independent. With ordinary stains the cerebellar cells can be seen as early as the 26th week of gestation (the earliest period examined). Brown neuromelanin granules do not appear until two and a half years of age but argentaffin granules, foreshadowing the production of pigment, are found in increasing numbers in the fetal and postnatal period. Homologues of the human cerebellar cells are reported in two species of monkey, Macaca nemestrina and Lagothrix sp. Neuromelanin, not previously observed in non-human cerebellar cells, occurs in M. mulatto and M. nemestrina. The proximity of the cerebellar melanoneurons to the ventricle raises the possibility that they are related to functions of the ependyma, or that they influence, or are affected by, constituents of the cerebrospinal fluid. The pathologic changes they undergo in Parkinsons disease and other disorders are to be described elsewhere.

Pathologic changes in the inner ear of audiogenic seizure-susceptible mice treated with 6-aminonicotinamide

Abstract The inner ears were studied histologically to determine a possible morphological basis for our earlier finding of the abolition of sound-induced seizures in inbred audiogenic seizure-susceptible mice treated with 6-aminonicotinamide (6-AN). A single intraperitoneal injection of 20 mg/kg of 6-AN resulted in elimination of sound-induced seizures and produced severe degenerative lesions in the cochlear duct of the seizure-susceptible mice. Similar cochlear lesions were produced in a control mouse strain (CF#1). The earliest lesions, first sought and clearly evident at 24 hours after the injection, were localized in the spiral ligament, the epithelium of the external spiral sulcus, and the lateral portions of the papilla acoustica. The acute degeneration was at its highest 3–5 days after the injection, when the medial portions of the papilla were also involved. The damage to the spiral organ (Corti) seen at that time is incompatible with a normal sensory input. The degree of damage is sufficient to explain the loss of, or marked restriction in, response to auditory stimuli, and the abolition of audiogenic seizures. In all animals treated with 6-AN, the lower basal turn and the upper second turn were more extensively damaged than the rest of the cochlea. However, in the longest surviving 6-AN-treated mice not even a remnant of the spiral organ could be detected. The spiral ganglion nerve cells were not damaged in the acute stage of 6-AN intoxication. The atrophy of the spiral ganglion which appeared in the late stages was, like the degeneration of the spiral organ, most severe in the lower basal and upper second turns. The changes in the spiral ganglion were interpreted as being secondary to the acute destruction of the spiral organ.

Sound-induced seizures in long-surviving prenatally x-irradiated rats

Abstract Twelve rats which had been exposed to 250 r of x-radiation in utero, on either the eighteenth or nineteenth day of pregnancy, were tested for their susceptibility to sound-induced seizures at a median age of 21 I 2 months. No significant association between incidence of seizures and prenatal x-irradiation was found. Some indication that x-irradiation in utero enhanced the reactivity of seizure-susceptible animals (whatever the causal factor for such susceptibility might be) was adduced from the findings. Contrary to the findings of others, it was concluded that audiogenic seizure susceptibility cannot be considered either a long-term or a sensitive indicator of the effect of x-irradiation upon the central nervous system.

AMERICAN ASSOCIATION OF NEUROPATHOLOGISTS: 38TH ANNUAL MEETING. ATLANTIC CITY. NEW JERSEY

Office of Secretary-Treasurer Institute of Pathology Case Western Reserve University 2085 Adelbert Road Cleveland, Ohio 44106 Phone: 216-368-2488, Fax: 216-368-8964 Email: aanp@case.edu http://www.neuropath.org Officers Other Executive Council Members Bette K. DeMasters, President Jeffrey A. Golden Mark L. Cohen, Vice-President Michael N. Hart Barbara J. Crain, President-Elect Roger E. McLendon Thomas J. Montine, Vice-President-Elect Joseph E. Parisi Tarik Tihan, Vice-President for Professional Affairs Harry V. Vinters George Perry, Secretary-Treasurer Clayton A. Wiley Kevin A. Roth, Assistant Secretary-Treasurer

American Association of Neuropathologists38th Annual Meeting. Atlantic City. New Jersey

Office of Secretary-Treasurer Institute of Pathology Case Western Reserve University 2085 Adelbert Road Cleveland, Ohio 44106 Phone: 216-368-2488, Fax: 216-368-8964 Email: aanp@case.edu http://www.neuropath.org Officers Other Executive Council Members Bette K. DeMasters, President Jeffrey A. Golden Mark L. Cohen, Vice-President Michael N. Hart Barbara J. Crain, President-Elect Roger E. McLendon Thomas J. Montine, Vice-President-Elect Joseph E. Parisi Tarik Tihan, Vice-President for Professional Affairs Harry V. Vinters George Perry, Secretary-Treasurer Clayton A. Wiley Kevin A. Roth, Assistant Secretary-Treasurer