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The role of intracellular pancreatic B cell serotonin in the dynamics of insulin release was investigated in an in situ perfused rat pancreas preparation. Animals were pretreated with 5-hydroxytryptophan (5-HTP) to increase the intracellular levels of serotonin (5-HT) as shown by fluorescence histochemistry. Despite a clear induction of intracellular 5-HT fluorescence in pancreatic islets neither the pattern nor the total amount of insulin released were significantly modified after perfusion with either glucose or tolbutamide. However, the L-amino acid decarboxylase inhibitor, RO 4--4602, significantly decreased both phases of glucose-mediated insulin release in normal animals as well as in those receiving 5-HTP.

An investigation was carried out to determine general staining and histochemical properties of rat atrial specific granules. It was found that these granules may be demonstrated using aldehyde fuchsin after pretreatments which involve oxidation or thiosulfation. This new way of demonstrating atrial granules is compared to other staining methods in terms of sensitivity and selectivity as well as to the nature of reactive groups that may be involved in the staining reactions. No lipid or carbohydrate were detected histochemically. Overall assessment of reactions suggests that atrial granules are a site of storage for a protein or polypeptide. Some of the tests indicate that these may contain tryptophan and sulfur-containing amino acids.

The uncinate process of the dog pancreas is devoid of A cells. Pancreatic extracts from the uncinate process of alloxanized dogs showed neither hypernor hypo-glycemic activity. These findings suggest that the lack of hyperglycemic effect of extracts from the uncinate process of the normal dog pancreas (11) simply indicates absence of glucagon and is unrelated to the presence of insulin. These results are in agreement with the hypothesis that glucagon is originated by the A cells of the pancreas. Neither the D nor X cells showed any sign of damage following alloxan injection during the period of observation.

The extracellular components of small grayish-yellow atherosclerotic dots and streaks removed at necropsy from 17 human aortae not later than 3 hours postmortem, were examined with the electron microscope. The broadened intercellular spaces which separated widely the intimal cells contained in more superficial layers moderately to intensely electron dense, fibrillar and granular fibrin material and other blood proteins. Small osmiophilic bodies of different sizes and configuration were present in the deeper portions of earlier lesions and were more numerous in more advanced lesions. The latter contained less fibrin. In addition, myelin-like figures were often seen either “free” in the extracellular space or associated with degenerating elastic elements, remnants of fibrin, and with cellular membranes of intimal smooth muscle cells. These myelinated bodies possessed often a core of variable electron density and texture, but it was possible to identify the cores at times as shreds of elastic tissue, basement membrane-like substance, or remnants of fibrin. It is believed on the basis of the present studies that degeneration of elastica, insuded fibrin and detached basement membrane of smooth muschle cells as well as the many osmiophilic bodies interpreted as precipitated lipoproteins derived from blood, contribute to the presence of the extracellular fat.

A comparative study was made of the cardioglobulin B content of the plasma of 26 normal adults and 20 newborn infants with the bioassay technique described by Hajdu and Leonard. The cardioglobulin B content in the plasma of infants was significantly lower than that of adults. Heparin was used as the anticoagulant in the blood samples throughout this study. It was noted that, when heparin containing phenol as a preservative was employed, the cardioglobulin B levels were lower in both groups.

The relationship of the morphology of the alpha cell and the amount of glucagon present in the pancreas of dogs and rabbits treated with drugs reputed to be toxic for the alpha cell has been further investigated. A summary is given of several experiments dealing with the lack of alpha cell damage in several species following the administration of drugs reputed to be toxic for the alpha cell. It is concluded that glucagon is produced by the alpha cell of the pancreas, and that much of the confusion on this subject probably results from a failure to recognize the technical difficulties involved in obtaining accurate morphological definition of the structure of the alpha cell at the time the tissue was excised from the body.

THE recent and excellent reviews of Cavallero (1), Foa (2) and Korp and Le Compte (3), have indicated that the inability to produce complete and permanent destruction of the A cells of the pancreas has greatly hindered our understanding of their function, particularly as a possible site of origin of glucagon. Recently, several substances have been used in an attempt to destroy the A cells, but there is as yet no general agreement on the exact nature of the A cell lesion thus obtained, nor on the effectiveness of these drugs in various animal species (4, 5, 6, 7, 8). The discoveryin our laboratory that the uncinate process of the dog pancreas is normally devoid of A cells, whereas the B and D cells are present (9), and than glucagon is probably absent in this portion of pancreas but abundant in the rest of the organ (10), prompted us to investigate the changes occurring in dogs deprived of their A cells.

Pancreatic islets have been studied by the electron microscopy of ultrathin sections in mature guinea pigs and cats. Alpha cells contain specific granules which are notably dense after fixation with osmium tetroxide. Their substance is homogeneous. They are enclosed within a vacuolar membrane. Other organelles such as the Golgi apparatus, endoplasmic reticulum, RNA granules and mitochondria are present inconspicuously, and without particular specialization. Beta cells of the cat and guinea pig differ in important respects. In the cat the specific granules contain an angular crystalloid element. The homologous structure in the guinea pig is spherical. These granules are enclosed in membranous envelopes. The densityof the granules is substantially less than those of alpha cells. Beta cells also differ from alpha cells in having a richer development of the endoplasmic reticular system, Golgi apparatus and RNA granules. The guinea pig beta cells also show a marked polarization of organelles.

A twenty-one year old woman with severe and prolonged renal failure associated with the acute onset of jaundice following delivery is described. The clinical, pathological and biochemical findings were consistent with fatty liver of pregnancy complicated by renal failure. The ultrastructural morphology of the renal lesion is described in detail and the changes in the glomeruli are interpreted as compatible with a lesion produced by intraglomerular fibrin formation. Such an event may have been the cause of the renal failure in this case.

A previous examination, done by others, of the endocrine cells of the canine pyloric antrum following its transplantation to the colon evidenced an increase in their number; the cell types involved, however, were not individualized. The present study further characterizes the changes occurring in the endocrine cells of the pyloric antrum of dogs following transplantation to the colon. The main change observed consists of hyperplasia of the enterochromaffin cells, with minor qualitative modifications in the antral gastrin-producing cells being noted only by electron microscopy. The response of the enterochromaffin cells cannot be readily explained but might be related to similar enterochromaffin cell hyperplasias found in human stomachs with peptic ulcers. Antrum transplantation to the colon in dogs appears to provide a promising experimental model for the study of the relationship between gastrin and other humoral factors (probably biogenic amines) in the mechanism of gastric secretion under normal as well as abnormal circumstances.

The pancreatic B cells from rats bearing a growth hormone-producing tumor (MtT-W15) were studied by electron microscopy before and after incubation in media containing alternatively low (60 mg./100 ml.) and high (300 mg./ 100 ml.) glucose concentrations. Tumor-bearing rats had been previously shown to have increased blood levels of somatotrophin and insulin and also to have B cells with increased responsiveness to in vitro glucose stimulation. B cells from tumor-bearing rats, when compared with controls, showed (1) an increased number of secretory granules, (2) a marked increase in the proportion of pale to dark granules (30 to 60 per cent, as compared with 5 to 25 per cent for controls), and (3) the presence of numerous dilated cisternae of rough endoplasmic reticulum containing a flocculent material resembling the core of the pale granules. The last observation may indicate that pale secretory granules are formed in the endoplasmic reticulum of these hyperactive B cells. The fact that the hyperfunctioning B cells present in tumor-bearing rats possess a high number of pale granules suggests that these granules participate in the processes of insulin synthesis, storage, and secretion. Pancreatic islets from control and tumor-bearing rats alternatively incubated in media with low and high glucose concentrations did not reveal significant morphological changes when compared with the nonincubated islets from the same animals. The extent of degeneration and necrosis observed in some B cells from control and tumor-bearing animals after incubation were unrelated to the glucose concentration in the incubation media.

SummaryFractions containing over 90% somatotrophs can be separated from suspensions of adenohypophysial cells by the techniques of velocity and density gradient centrifugation. These isolated somatotrophs, as shown by radioimmunoassay, contain growth hormone. Light and electron microsopic studies show that the isolated somatotrophs retain their structural integrity. These somatotrophs incorporate 14C-amino acids into protein in linear fashion during 3-hr incubation.The expert technical assistance of Allan Morris, Oriette Morris, Margaret Evans and Blake Guggins is acknowledged.

Although histochemical, immunohistochemical, and electron microscopic methods have led to the identification of a large variety of endocrine cells in the upper gastrointestinal mucosa, no conventional light microscopic technique capable of the simultaneous identification of these cells has been reported. Such a staining method would be of considerable value to the pathologist as the malfunction of the endocrine cells of the gut, which produce numerous digestive hormones and biogenic amines, is closely related to a number of clinical conditions afflicting man. In this work, after testing three different polychrome staining methods, it has been concluded that a slightly modified Herlant's tetrachrome in tissues fixed in Zenker-formol is the procedure of choice. This method allows the distinction of several different cell types in the upper gastrointestinal mucosa of man and dog and permits the easy identification of the gastrin-producing cells on a routine basis. This identification has been confirmed in the case of two patients with gastrin cell hyperplasia, seen by both light and electron microscopy. Herlant's tetrachrome has proven valuable in the screening of human as well as experimental gastrointestinal tissues and it has been found to be very suitable for recognizing gastrin-producing cell hyperplasias. The usefulness of this method is expected to increase with the establishment of further correlations between the light and electron microscopy of the endocrine cells of the gut.

Summary Biopsies from 18 human cervices were studied by the light and electron microscope techniques in order to determine the nature of the “P.A.S.-positive basement membrane of light microscopy.” Under the electron microscope, the light microscope basement membrane was shown to be composed of connective tissue fibers (particularly reticulum fibers) in the 0.4 to 0.5 µ area of the stroma immediately subjacent to the electron microscope basement membrane. Incubation of the sections with collagenase resulted in failure of the tissue to show the “P.A.S.-positive basement membrane of light microscopy.”

Yellow 5-HT fluorescence has been histochemically demonstrated in rat pancreatic islet cells in animals injected with L-5-HTP with or without pretreatment with the monoaminoxidase inhibitor nialamide. This fluorescence was not observed after inhibition of the aromatic amino acid decarobxylase. The results strongly suggest the presence of a tryptaminergic mechanism in the rat islet cells.

MacConaill's lead-hematoxylin as modified by Solcia et al. was found to be a highly selective stain for the specific granulation of atrial cardiocytes in the rat. The specific atrial granules were stained blue-black. Contrast was enhanced by counterstaining in a saturated solution of tartrazine in Cellosolve. The stain is compatible with several fixatives and may be used with paraffin or Epon-embedded material.

The "specific granule" population of right atria of female hooded rats increased with age.

Skeletal muscle biopsy specimens from diabetic and nondiabetic subjects were examined by light and electron microscopy. Distinctive lesions in the capillaries were found in twelve of sixteen specimens from diabetic subjects but in only three of nineteen from nondiabetic subjects. The development of the concept of diabetic microangiopathy is reviewed and discussed in relation to other vascular lesions complicating diabetes, and in relation to an abnormal response of the peripheral circulation to adrenalin infusion which has recently been described in human diabetes.

A series of recent observations on different aspects of the chemistry and metabolic actions of bile have led us to investigate the possibility that bile may induce pancreatitis through the physicochemical detergent properties of its salts. To determine the relative importance of proteolytic enzymes on the one hand, and the detergent action of bile on the other, in the pathogenesis of bile-induced experimental pancreatitis in the dog, the early morphologic changes (1–30 min) produced by the intraductal injection of the following substances were investigated: (1) autogenous bile; (2) bile salt; (3) an anionic detergent, sodium lauryl sulfate (SLS); (4) trypsin; (5) a cationic detergent, cetrimide; (6) a neutralized mixture of SLS and cetrimide; and (7) saline solution. Autogenous bile, bile salts and SLS produce pancreatitis of similar morphologic appearance, characterized by punched-out areas of coagulation necrosis. Trypsin-induced pancreatitis was distinctly different from that produced by bile, bile salts and SLS. In trypsin pancreatitis, irregular areas of necrosis and hemorrhage were seen. Inactivation of the detergent activity of SLS by mixing it with the cationic detergent, cetrimide, reduced the capacity of SLS to induce pancreatitis similar to that induced by bile and bile salts. These data seem to indicate that the early phases of bile-induced pancreatitis in our experiments are unlikely to result from the liberation of trypsin, but are related instead to the detergent activity of bile salts.

Clear cells, identical in fine structure to Langerhans cells of the human epidermis, occur in the intercellular spaces of the squamous epithelium of the cervix. There is an apparent increase in the number of Langerhans cells in the cervical epithelia from cases with cardinoma in situ. Langerhans cells of the cervix are frequently mistaken for lymphocytes or for epithelial cells that have undergone cytoplasmic shrinkage. The proper identification of Langerhans cells and other clear cells in the cervical epithelium may eliminate some unnecessary confusion in the interpretation of cellular changes in neoplasia.

Electron microscopy of mammalian atrial muscle cells reveals a population of specific granules suggesting that the atrial muscle cells may have a secretory function. As a preliminary step towards the investigation of the function of the specific granules, a procedure was designed to isolate these particles by differential and density gradient centrifugation of rat atrial homogenates. The specific granule preparation obtained showed a considerable degree of purification with respect to marker enzymes. The isolated granules retained their in situ fine structure and staining properties.

Summary1) A study of levels of several electrolytes and various other substances concerned with protein, lipid and carbohydrate metabolism has been made in blood and urine of dogs subjected to removal of alpha cell containing part of pancreas by selective, partial pancreatectomy. 2) Despite previous suggestions by others, there was no definite evidence in our work of a relationship between functional activity of alpha cells and any of the substances studied, with the possible exception of blood non-protein nitrogen. Since this was significantly elevated in all experiments and was not associated with a significant increase in urinary nitrogen excretion nor loss of weight, it is possible that absence of alpha cells exerts a slight inhibitory effect on protein synthesis.

A reevaluation of the silver methenamine reaction as an electron stain has ensued from recent use of glutaraldehyde fixation alone. By this technique, three cell types of rat adrenal medulla were found: (i) the norepinephrine-containing cells showed selectively stained, irregular, black granules; (ii) the epinephrine-containing cells showed round, light-grey granules; and (iii) the third cell type showed round granules like those of epinephrine-containing cells, but black in color, similar to those of the norepinephrine-containing cells.

SummaryMost of the uncinate process of the dog pancreas is devoid of alpha cells, whereas these are found in the remainder. On the other hand argentaffin cells are sparsely but evenly distributed throughout the pancreas. Extracts of the portion of pancreas devoid of alpha cells show no hyperglycemic activity when 1 g aliquots are used. When 4 g portions are employed, a very mild initial hyperglycemia does occur. These findings are interpreted to support the opinion that glucagon originates from the alpha cells but are not definitive.

Cytological changes in uterine stromal cells of the rat during induced primary decidua formation have been examined electron microscopically. Decidua forming stroma was examined at daily intervals for the five days during which the reaction reaches maximal hypertrophy and hyperplasia and was compared with pseudopregnant, non-decidual (control) endometrium. Stromal cells of control uteri resemble embryonic fibroblasts. They appear to be of two types, depending on whether they contain rough – or smooth-surfaced endoplasmic reticulum. As the decidual reaction progresses, the cells enlarge and become binucleate; cells which contain exclusively rough surface endoplasmic reticulum no longer are evident. Glycogen and fat become abundant, the former in association with smooth-surfaced membranes of the endoplasmic reticulum. Mitochondria become more numerous, smaller, and show evidence of a rearrangement in internal organization. There is a pronounced increase in a fine intracytoplasmic fibrillar component; and a spectrum of “microbodies” and lysosomes appears. At the height of the reaction, the stroma appears epithelioid. The possible functional significance of these changes is discussed.

Summary1. Cortisone acetate administered intramuscularly to rabbits caused the gradual appearance of glycosuria which reached a maximum at the 5th to 9th days and then declined. Increased dosage reestablished the glycosuria but it again regressed. Morphologically, the most prominent lesion observed was ductular and centroacinar proliferation and the formation of irregularly shaped and “Mulberry” islets. In addition, numerous mitotic beta cells were observed up to 10 days after starting cortisone treatment.Similarly, degranulation of the beta cells was most prominent at early stages. Glycogen infiltration seemed to appear first in the ductular tissue and required a greater degree and duration of diabetes before affecting the beta cells. 2. The degranulation and increased mitotic activity of the beta cells are thought to be a response to hyperglycemia as is the glycogen infiltration of ducts and beta cells. The proliferative activity on the other hand is considered to represent a more direct action of corti...

Striking glomerular changes are seen electron microscopically in rat kidneys after acute uranyl nitrate poisoning. More interesting than the several glomerular epithelial cell reactions to this injury, perhaps, is the development of the nodular centrolobular lesion containing collagen fibers. The glomerular epithelial cell changes include loss of foot processes , the appearance of dense deposits in foot processes or in the larger portions of cytoplasm which replace lost foot processes, hyaline droplets , other cytoplasmic bodies with varying internal membranes and granules, myelin figures , and cytoplasmic vacuoles . The functional significances of these changes and of the observed proteinuria, polyuria, and oliguria are discussed. The nodular centrolobular lesion was identified with a trichrome stain after embedding in methacrylate. As seen with the electron microscope it consists of several components lying between the central dense layer of the basement membrane and endothelial cells. Separately distinguished components include intercapillary cells and their processes lying in intimate contact with extracellular (a) small dense granules 30 m μ in diameter, (b) large bodies 400 m μ in diameter, vaguely forming rough cords, and (c) collagen fibers , randomly oriented and appearing within four days after injection of uranium. The intercapillary cells, often containing clear vacuoles with very dense and thick osmiophilic walls, may later prove to be endothelial cells but their intimate association with collagen fibers raises other alternatives.

SummaryThe changes induced in concentration of rhamnose, mannose, fucose, glucose and galactose in the kidney of rabbits treated with various steroids were studied using a semi-quantitative chromatographic method. The findings are discussed in relation to the pathogenesis of diabetic glomerulosclerosis.

In recent years there has been considerable interest in the identity, structure and function of delta cells of pancreatic islets. Williams states that the Zollinger-Ellison Syndrome is associated with neoplasms of delta cells and that these cells secrete gastrin. However, other functions have also been attributed to these cells. An excellent critical review on the identity, structure and possible function of delta cells has been published by Fujita. Clearly all new criteria for identification of delta cells must refer back to those given by Bloom in his original description in 1931.The present report deals with a malignant islet cell tumor of the pancreas in a case autopsied twelve hours after death. By light microscopy tumor cells possessed the classical tinctorial properties of delta cells; the tumor was thus classified as a delta cell carcinoma. Considerable confusion exists on the ultrastructural identification of delta cells in man. Hence, it was decided to investigate the fine structure of these tumor cells and to compare them to non-tumor islet cells of the same patient. To best interpret our results in post mortem material the pancreas of three patients autopsied at three, six and twelve hours after death were processed and studied in a similar manner as the pancreas bearing the tumor. By electron microscopy three types of islet cells could be identified in pancreas taken three hours post mortem.