Erland Nelson

ELECTRON MICROSCOPIC OBSERVATIONS ON NORMAL HUMAN INTRACRANIAL ARTERIES.

IN SPITE OF the interest displayed by physiologists concerning the regulation of the cerebral circulation, the obvious importance of a thorough knowledge of the normal fine structure of intracranial arteries to pathologists, and the relevance of this information to clinicians, there have been no electron microscopic reports of normal human intracranial vessels. Pease and Molinaril have described the fine structure of pial arteries in experimental animals, and other investigations have been concerned with muscular and elastic arteries from different organs in various species.2-6 The ultrastructure of human atherosclerotic lesions has been described in systemic vessels2 and also in the meningeal arteries.? However, in general, human postmortem material has been avoided because of the impossibility of immediate fixation of such specimens. While delayed fixation produces undoubted artifacts, there are obvious advantages to studying human vascular disease rather than either natural or induced vascular disease of animals. Because of the importance of studying normal human vessels as a necessary preliminary to investigating human degenerative vascular disease, this study utilizing routine autopsy material was undertaken.

Electron microscopic and histochemical studies in diffuse sclerosis: (Sudanophilic type)

THE DlFFUSE SCLEROSES are a diverse group of diseases which predominantly affect white matter of the brain. They almost certainly do not have the same etiology or pathogenesis, and their histologic peculiarities have been the basis for some of the recent and more reasonable of the many attempts at classification.] Several investigations have utilized biochemical or histochemical technics to characterize further these conditions,4-0 but the diffuse scleroses remain an incompletely understood group of diseases which are equally b a i n g to the clinician and the pathologist. It was, therefore, considered justifiable to begin a series of cerebral biopsies with combined electron microscopic and histochemical studies on carefully selected patients who were clearly sder ing from an incurable and progressive cerebral disease. The relatives were told of the very remote possibility that this procedure would benefit the patient himself, and the frankly investigative nature of the biopsy and subsequent studies was emphasized. This case represents the first electron microscopic study of biopsy material from a case of cliff use sclerosis. The ultrastructural and histochemical features of the cerebral lesions will be considered in detail, and the clinical-pathologic aspects of this rather unusual case will be dealt with in a subsequent publication.7

Shy‐Drager syndrome Diagnosis and treatment of cholinergic dysfunction

Two patients with Shy-Drager syndrome demonstrated unusually widespread and unequivocal cholinergic dysfunction as well as the usual evidence of adrenergic insufficiency. Progressive constipation preceded impotence, nocturia, hesitancy in micturition, anhidrosis, orthostatic hypotension, and xerostomia. Nonautonomic neurologic signs appeared several years later. Cholinergic dysfunction involved eyes, lacrimal glands, salivary glands, heart, gastrointestinal tract, urinary bladder, and sweat glands. Subcutaneous administration of bethanechol chloride—a muscarinic receptor agonist—improved tearing, salivation, sweating, and gastrointestinal and bladder functions. Daily administration of this drug resulted in symptomatic improvement of the autonomic functions, and relapse followed discontinuation of treatment.

Ultrastructural observations on phagocytosis of bacteria in experimental (E. coli) meningitis.

A bacterial meningitis was produced by injection of 0.1 cc of a suspension of E. coli intracranially in Syrian hamsters. The animals were sacrificed at intervals from 2 to 72 hours after infection; tissue was removed from the living animals and prepared in the usual manner for electron microscopy. Ultrastructural relationships between bacteria and polymorphonuclear leukocytes and macro-phages in the subarachnoid space were studied. With both cell types there were cytoplasmic extensions around the free organism, with ingestion of the bacterium and fluid in a vacuole whose limiting membrane was derived from the phagocytic cell wall. The relation between this process and pinocytosis was briefly discussed. Degenerating bacteria in polymorphonuclear leukocytes were associated with small amounts of osmiophilic, finely granular material resembling that seen in lysosomes. Considerably greater amounts of this “lysosome material” were seen in the pliagocytic vacuoles of macrophages, although the bacteria were often relatively intact. It is suggested that this material is produced within the cytoplasm of the phagocyte in response to the bacteria, contains hydrolytic enzymes, and may be concerned with bacterial digestion. The fine structure of various types of inclusion bodies seen in macrophages was described.

The Innervation of Human Intracranial Arteries: A Study by Scanning and Transmission Electron Microscopy

Combined scanning (SEM) and transmission (TEM) electron microscopy was done on external features of human intracranial arteries, including large vessels at the base of the brain and secondary and tertiary branches of the middle and posterior cerebral arteries. Linear structures lying on the external surface of these arteries could be easily identified and followed for distances of several millimeters. These were well-circumscribed and often branched before disappearing into the depths of the adventitia. With TEM the linear structures observed with SEM could be identified as bundles of myelinated and unmyelinated axons embedded in collagenous fibrils, with surrounding perineurial sheaths composed of overlapping fibrocyte processes. The scanning electron microscope provides a striking and relatively simple method for studying the extent and distribution of vascular innervation.

Virus-Containing Leukocytes in Polioencephalitis

Crystalline aggregates of strain MM virus occur in polymorphonuclear leukocytes in association with osmiophilic granular structures which are occasionally membrane-bound. This suggests either a phagocytosis and segregation of virus by leukocytes, analogous to the disposition of bacteria by leukocytes, or a utilization of the leukocyte by the virus as a host cell for virus replication.