The fine anatomy of the human spinal meninges. A light and scanning electron microscopy study

The fine anatomy of the human spinal meninges was examined in five postmortem spinal cords taken within 12 hours after death from patients aged 15 months to 46 years. Specimens of spinal cord were viewed in transverse section and from the dorsal and ventral aspects by scanning electron microscopy. Transverse sections of spinal cord and meninges were also examined by light microscopy. The arachnoid mater was seen to be closely applied to the inner aspect of the dura. An intermediate fenestrated leptomeningeal layer was observed attached to the inner aspect of the arachnoid mater and was reflected ventrally to form a series of dorsal septa. As it arborized laterally over the surface of the cord to surround nerves and blood vessels, the intermediate layer became highly fenestrated but remained distinct from the pia and arachnoid mater. The pia mater appeared to form a continuous layer which was reflected off the surface of the cord to coat blood vessels within the subarachnoid space in a manner similar to that described in the leptomeninges over the human cerebral cortex. Each dentate ligament consisted of a collagenous core which was continuous with the subpial connective tissue and was attached at intervals to the dura; pia-arachnoid cells coated the surface of the dentate ligaments. The present study suggests that the fine anatomy of the human spinal meninges differs significantly from that described in other mammals.     

The human bulbo-urethral glands. A transmission electron microscopy and scanning electron microscopy study

This paper investigates the ultrastructure of human bulbo-urethral glands using specimens obtained at surgery. The tubulo-alveolar endpieces of these glands are lined by typical mucous cells in different stages of the secretory cycle. The most interesting features of their cytoplasm are membrane-bounded bodies with a filamentous texture that usually fuse with the mucous droplets before they discharge into the lumen. Cells with apical dark granules are sometimes encountered in the ductal portions of the gland, which are probably ductal cells endowed with a scanty synthetic and secretory activity. Myoepithelial cells are not very numerous and are observed around mucous cells only.     

A study of arterial prostheses by scanning electron microscopy.

Scanning electron micrographs were taken of ten different vascular prostheses. The micrographs showed that some prostheses were damaged and some had traces of chemicals on their surface. The application of standard vascular clamps damaged most grafts and some showed remarkable changes on resterilization.     

Strength of microvascular anastomoses: comparison between the unilink anastomotic system and sutures

The Unilink system, a mechanical anastomotic device, was compared with standard suture techniques in terms of anastomotic strength under conditions of uniaxial loading. Twenty-five rabbits underwent Unilink and suture anastomosis of both carotid arteries and facial veins. Animals were sacrificed at 1 hour (five animals), 2 weeks (10 animals), and 16 weeks (10 animals), and all vessels were tested by constant loading in a material testing machine. The maximum load required to disrupt the anastomosis as well as the site of vessel failure were recorded. All 100 anastomoses were fully patent as evaluated by clinical testing. At 1 hour and 2 weeks, the Unilink arterial anastomoses were consistently and significantly stronger than the sutured anastomoses. At 16 weeks the sutured arterial anastomoses were significantly stronger than Unilink. The Unilink anastomoses, however, remained approximately 50% stronger than unoperated normal vessels. No statistical differences were observed in the strength of venous anastomoses at any of the intervals tested. There were no statistical differences in the sites of failure of the vessels under loading (i.e., at the anastomosis or proximal or distal to it) between the two techniques.     

A study of glucagonomas by light and electron microscopy and immunofluorescence.

Five tumors associated with the complete glucagonoma syndrome, as well as a series of glucagon-cell adenomas from three patients without this syndrome, were investigated by light and electron microscopy and by immunofluorescence. All tumors associated with the syndrome were large, from 3 to 35 cm along the major axis, and three of them were proved to be malignant. No common histologic arrangement of tumor cells was apparent for the five neoplasms examined. Immunofluorescent staining for glucagon and glicentin was carried out: while most cells were negative, a varying number of scattered cells were positive with both antisera in all tumors except one; three tumors contained more glicentin- than glucagon-immunoreactive cells. Moreover, three tumors were multihormonal, witn cells positive for pancreatic polypeptide and/or insulin. Ultrastructurally, the secretory granules of cells from these tumors were not typical of those found in A-cells from adult human islets. The glucagon-cell tumors from patients without the syndrome were benign, usually multiple, and were small, with diameters from 0.5 mm to 1 cm. In most cases, the cells from these neoplasms arranged in a characteristic pattern (ribbonlike or "gyriform"). In most tumors, the majority of cells showed both glucagon and glicentin immunofluorescence and the ultrastructural appearance of their secretory granules was similar to that of normal islet A-cells. From the morphologic point of view, therefore, cells from tumors not associated with the glucagonoma syndrome resemble normal glucagon cells more closely than those from tumors associated with the syndrome.     

A study of the ultrastructure of urinary calculi by scanning electron microscopy

Summary A study of urinary stones obtained from patients after surgery in the Medical College Hospital, Trivandrum, under the scanning electron microscope showed the presence of calcium oxalate and calcium biphosphate crystals as the main constituents. However, the pattern of the different phases of crystal growth was not uniform. Within the crystal lattice, fibrous structures, possibly of protein matrix, were invariably observed. Electron microscopy may be usefully adapted as a particularly suitable method for ultramicroscopic investigation of the fine structure of urinary stones including single crystal surface structure, section of urinary calculi and for possible presence of hitherto unknown components within the calculus.     

Proprioception in the anterior cruciate ligament of the human knee joint--morphological bases. A light, scanning and transmission electron microscopy study]

In 21 human anterior cruciate ligaments removed with their synovial sheaths during autopsy and operation, nerves and nerve endings were demonstrated by light microscopy, scanning electron microscopy and transmission electron microscopy. Ultrastructural examination allowed a classification of nerve endings into three types: Ruffinian corpuscles, Pacinian corpuscles and free (afferent and efferent) nerve endings. The nerve endings corresponded to those characteristic of articular capsules. The anterior cruciate ligament shows evidence of a proprioceptive function besides its stabilizing function, which is based on its collagenous structure. Together, they probably represent the most important factor in the dynamic stabilization of the knee joint. At present it is only possible to speculate on the potential clinical significance of these findings, for example in development of rehabilitation programs and prevention strategies offering protection against anterior cruciate tears. This also applies to the question of whether to preserve the ligament during surgery for ruptures and knee-joint prostheses.     

Pathology of the intima in coarctation of the aorta: a study using light and scanning electron microscopy

In the adult type of coarctation of the aorta the lumen is constricted by a shelf of fibromuscular tissue that protrudes from the dorsal wall of the aorta at a point near the site of insertion of the ligamentum arteriosum. The intima covering this constricting shelf has been studied using conventional light microscopy and scanning electron microscopy of surgical specimens of coarctation removed at ages varying from 2 to 46 years. Immediately proximal to the stenosis, the intima was found to run in fine longitudinal folds that radiated into the orifice. On the distal side of the shelf the intima was grossly irregular with deep longitudinal and transverse folds that gave it a convoluted appearance resembling the surface of the brain. In adults and older children the intima immediately distal to the orifice was covered with a laminated layer, distinct from the elastica, which often gave positive staining reactions for fibrin. Intimal thickness increased irregularly with age, but large increases of 500 μm or greater were found only in patients over the age of 15 years. These findings are consistent with the view that the constriction has both a fibroelastic component that is congenital and a fibrous component that is acquired and progressive. It is suggested that this progressive element is caused by deposition of fibrin on an abnormal intimal surface in a region of turbulent blood flow. Such a mechanism would explain the occasional recurrence of coarctation of the aorta after surgery. This may be due to failure to remove the abnormal area of endothelium completely and to persistent abnormalities of blood flow at the site of anastomosis.     

Scleroderma of the breast: light and electron microscopy study

The initial presentation of scleroderma (systemic sclerosis) with a manifestation involving only the breast has not been reported in the literature. Previous reports document scleroderma occurring after cosmetic mammaplasties. The presumed etiology is related to silicone, which has some adjuvant effect in development of the disease. This report documents a case of scleroderma presenting as a breast problem in a 28-year-old woman without prior exposure to silicone. We also describe the light and electron microscopy findings.     

A light and scanning electron microscopic study of osteocyte activity in calcium-deficient rats

Summary The material herein is an extension of an earlier study of osteocyte lacunae in calcium-deficient rats, utilizing morphometric measurements in undecalcified bone sections and scanning electron microscopy. The results confirm our earlier finding that bone resorption resulting from a low-calcium diet is not accompanied by osteocytic resorption.     

Lyophilized veins studied by scanning electron microscopy.

Human saphenous veins were studied by scanning electron microscopy. The intention was to analyze the suitability of lyophilized homologous veins for homografting when no autologous venous material is available for replacement of obstructed arterial segments. Cross-sectioned specimens revealed the intimal layer of the venous wall to be compactly structured, while the median and external parts were found to be loosely organized and contained numerous cavities. The luminal surface coat displayed the typical aspects of an intact endothelium with occasional fine deposits of fibrin. Defects of the inner layer were only rarely observed, and are caused when the endothelium was stuck to the PVC catheter prior to lyophilization. From a morphological point of view, lyophilized veins seem to be sutiable for replacement of arterial segments. Based on our findings suggestions are made for optimal preparation of the venous material.     

Early versus delayed heparin reversal after carotid endarterectomy in the dog. A scanning electron microscopy study

The present study investigates the hematological reaction to arterial injury during the first 10 minutes after endarterectomy in dogs to determine if heparin reversal during this early period predisposes to thrombus formation. Known platelet physiology would predict that heparinization during this early period would be useful to allow a fibrin-free platelet monolayer to form. After systemic heparinization (145 mu/kg) of the experimental animals, 42 endarterectomies were performed. Blood flow was then resumed for specific periods of time, and the vessels were prepared for scanning electron microscopy. Group 1 vessels (from the unheparinized control group) revealed mural thrombus formation after 10 minutes of blood flow. Group 2 vessels revealed the progressive formation of a fibrin-free platelet monolayer after 2, 5, or 10 minutes of blood flow resumption under systemic heparinization. Group 3 arteries, harvested at 10 minutes, underwent immediate (within 1 to 2 minutes after resumption of flow) heparin reversal with protamine sulfate, and demonstrated numerous patches of fibrin covering the platelet monolayer. Group 4 arteries, studied after 3 hours of blood flow, also underwent immediate heparin reversal. Two of these seven specimens had clumps of fibrin overlying the platelet monolayer. The Group 5 vessels had heparin reversal at 10 minutes, and demonstrated no fibrin overlying the platelet monolayer after 3 hours of blood flow. This study demonstrates the formation of a fibrin-free platelet monolayer over the endarterectomized vessel wall within 10 minutes of resumption of flow under systemic heparinization. These findings suggest that heparin may safely be reversed following a carotid endarterectomy if one awaits the initial critical 10 minutes of blood flow.     

A scanning electron microscopy study of changes in rat colonic mucosa during carcinogenesis

Scanning electron microscopy (SEM) has been used to examine morphological changes on the colonic mucosal surface during experimental carcinogenesis. Seventy-five rats were given weekly injections of dimethylhydrazine (DMH) and 25 rats acted as controls. Groups of DMH-treated and control rats were sacrificed at regular intervals and specimens of their colons were examined by SEM. The normal colonic mucosa had an orderly architectural pattern which remained constant throughout the experiment. Abnormalities in the mucosa of treated rats were detected as early as 6 weeks after the first injection of DMH and thereafter there was progressive distortion of the crypts, development of pericryptal fissures and mucosal surface irregularities, and eventually, formation of focal protuberances, polyps, and tumors. The findings indicate that there is a definite pattern of progressive mucosal abnormalities commencing long before the development of focal colon tumors and that SEM is useful in the detection of these abnormalities.     

Collection and evaluation of normal exfoliated urinary bladder cells in man using scanning electron microscopy.

Normal exfoliated urinary bladder cells were collected from midstream urine samples from 21 male patients. Procedures for urine filtration using Millipore filters of Nucleopore filters, cell fixation and preparation for scanning electron microscopy investigation were developed. Correlations were made between the surface morphology of exfoliated cells and that of biopsies from different anatomical regions of the urinary bladder. Scanning electron microsocopy (SEM) of exfoliated normal urinary bladder cells proved to be a more sensitive method for discovering cellular surface details than light microscopy. This information forms the basis for further SEM studies of cell surface alterations due to urothelial diseases.     

The endometrium of intact or castrated rats. Effects of hormonal stimulation. A scanning electron microscopy study

The endometrium of female rats during the estrous cycle and of female ovariectomised rats under hormone stimulation, has been studied by scanning electron microscopy. The endometrium underwent marked cyclical changes; the development of microvilli was noted before ovulation, and secretory phenomena started during proestrus but remained discrete throughout the cycle. The rat endometrium was also characterised by the fact that ciliated cells were scarce. Following ovariectomy, the endometrial surface pattern was similar to that of the menopausal woman endometrium. After estrogen or estroprogestogen stimulation, by the methods usually employed in endocrine pharmacology, the general endometrial pattern was very different to that observed during the reproductive cycle in rats.     

Nodular fasciitis of the oral mucosa: light and electron microscopy study

Nodular fasciitis of the oral mucosa is a rare lesion. The present article describes an additional case and discusses the difficulties in the histologic diagnosis. The final diagnosis is based on immunohistochemistry and electron microscopic morphology. Nodular fasciitis should be considered in the differential diagnosis of swellings in the oral mucosa.     

Current PTFE grafts: a biomechanical, scanning electron, and light microscopic evaluation.

Two currently available brands of PTFE grafts (Goretex and Impra) were studied in a canine femoral artery model to determine whether changes in the manufacturing processes of the two grafts, which increased their strength, had altered the biophysical properties and the histological reactivity of either graft. Both grafts were found to be similar except for differences in their suturability. Their in vivo dynamic compliances were almost identical (1.2 +/- 0.35 vs. 1.2 +/- 0.45). (Scanning electron microscopy showed endothelialization of the grafts only adjacent to the anastomoses, and light microscopy demonstrated similar degrees of histologic incorporation by the host tissues, though of slower tempo than that previously described. These results are examined and discussed with regard to the suitability of this model for characterizing new arterial prostheses of small to medium diameter.     

Comparative light and scanning electron microscopy studies of the morphologic structure of ligament insertions into the bone

The microstructure of the osseous ligament insertion was studied by light microscopy and scanning electron microscopy using the insertion of the membrana interossea antebrachii as an example. The scanning electron microscopical findings of specimens which had been prepared by freeze-fracturing confirm the typical 4-zone-structure of the osseous ligament insertion. The findings emphasize the functional importance of both zones of unmineralized and mineralized fibrous cartilage, which represent an effective shock absorbing system for the collagenous structures of the osseous ligament insertion.