Cytoplasm Of Acinar Cells Research Articles

Staining of native and grafted exocrine rat pancreasby an interleukin-2 receptor specific monoclonal antibody

Immunohistological studies of native and grafted rat pancreas tissue with mouse anti-rat monoclonal antibodies revealed an unexpected staining pattern of MRC Ox 39 which binds specifically to rat interleukin-2 (IL-2) receptors. While the cytoplasm of acinar cells of native pancreas was stained, the lumina of the acini remained uncoloured. In grafted exocrine tissue, the staining pattern was quite reverse. Only the apical cytoplasm of acinar cells was stained while the acinar lumina exhibited an intense stain. Common binding sites shared between the IL-2 receptor and a hypothetical exportable protein in acinar cytoplasm could explain these observations.

Purification of Ca2+-ATPase from rat pancreatic acinar plasma membranes using calmodulin-affinity chromatography.

Although a great deal is known about the stimulatory role of calcium in stimulus-secretion coupling, little is known about the mechanism by which intracellular calcium is regulated. The free calcium concentration in the acinar cell cytoplasm is typically between 10−5–10−7 M, in contrast to the much higher levels of calcium (approximately 10−3 M) in the extracellular space (Peterson, 1982). Calcium therefore penetrates into cells continuously down its electrochemical gradient by passive diffusion. In order to maintain a homeostatic environment in the cell and assure proper cell function, free calcium must be continuously removed.

Hamartoma of the parotid gland: A case report with immunohistochemical and electron microscopic study

A case of a solid parotid tumour in a 16-year-old boy is presented. Histologically, the tumour demonstrated some peculiar findings. An acinar pattern was predominant although every component seen in the normal salivary gland was present, namely, serous and mucous gland acini, ducts, myoepithelial cells, adipose and lymphoid tissue. Large eosinophilic granules were abundant in the large acinar cell cytoplasm. Immunohistochemically, the tumour demonstrated the proteins which are present in the normal parotid gland, for example, amylase, lactoferrin and lysozyme. Electron microscopic features were quite similar to those of normal parotid tissue except for accumulation of a large number of cytoplasmic granules in the acinar cells. There has been no previous report of a tumour with the same features as seen in this case. Our pathological diagnosis is hamartoma, although the possibility of hyperplasia or neoplasia can not be excluded.

Induction of a specific (LM) protein in the submandibular gland of the rat by repeated amputation of the lower incisor teeth.

Chronic administration of the beta-adrenergic agonist isoproterenol (IPR) leads to marked hyperplastic/hypertrophic enlargements of the parotid and submandibular glands in rats and mice with concomitant changes in the composition of both the glands and the saliva. Conspicuous among the alterations of the submandibular saliva is the appearance of a 13,000 Mr protein, termed LM (large mobile) protein. Repeated amputation of the lower incisor teeth also causes enlargements of the major salivary glands in rats. In this study, we have compared the enlargements of submandibular glands of rats produced by IPR administration or teeth amputation with respect to the relative levels of the LM protein in gland extracts and saliva. Administration of IPR-HCl (40 mg/kg) twice daily for 5 days or amputation of the lower incisor teeth 3 times a week for 3 weeks resulted in a 2.2-fold increase in the weight of the submandibular gland. Amputation for one week led to a 1.4-fold increase in gland weight. Double immunodiffusion in agar antibodies against the purified LM protein gave a single precipitin line with gland extracts and saliva of IPR-treated and teeth-amputated rats, indicating immunological identity of the reacting antigens. No precipitin lines were seen with gland extracts or saliva of untreated rats. Immunoblots of pooled saliva obtained from IPR-treated or teeth-amputated rats revealed a single protein band of the same electrophoretic mobility in SDS-polyacrylamide gels when stained using anti-LM antibodies. The relative concentrations of LM protein in gland extracts and saliva were measured by a solid-phase enzyme-linked immunoabsorption assay using antibodies against the purified LM protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphometric and fine-structural studies of rat pancreatic acinar cells during early postnatal life.

Pancreatic acinar cells of rats obtained at 1, 2, 3, 5, 7 and 14 days of age were examined using fine structural and morphometric techniques. From 5 days of age onwards, the acinar cells were analysed twice per day, at 20.00 h and 08.00 h. The present study demonstrates changes in the average volume of the cell, nucleus and cytoplasm, and volume densities of various cytoplasmic organelles during the first two weeks after birth. During early postnatal life, the volume density of rER increases, whereas that of zymogen granules decreases. From 5 days of age onwards, the volume densities of these two organelles differ significantly at 20.00 h and 08.00 h. During the first 2-3 days after birth, inclusion body-like structures appear in the cytoplasm of acinar cells; they contain aggregated zymogen granules and, sometimes, amorphous structures of cytoplasmic organelles. These structures also occur in interstitial cells and cells located in the intercalated region between acinar and ductal epithelial cells. Serum level of alpha-amylase activity is high at birth, compared with other stages during the first three weeks. Degenerating acinar cells and cell debris can be seen in the acinar and ductal lumina during these stages, a feature suggesting holocrine secretion. Cellular polarity appears to be incomplete during the first two or three days after birth.

Carbonic anhydrase in mouse salivary glands and saliva: a histochemical, immunohistochemical, and enzyme activity study.

Mouse parotid gland and saliva were studied by histochemical, immunohistochemical, and activity measurements for carbonic anhydrase. Hansson 's histochemical reaction for carbonic anhydrase revealed positive enzyme activity in the parotid acinar cell cytoplasm and little or no reaction in the secretory granules. The luminal contents in all of the glandular duct systems also reacted positively, but the duct cells themselves were only weakly positive. Ultrastructural observations confirmed the light microscope histochemical localization and, in addition, revealed luminal content activity in intercellular ducts. Purified carbonic anhydrase isolated from mouse salivary glands was used to raise antibodies in rabbits. Localization of carbonic anhydrase by direct immunolabeling with fluorescein-coupled antibody and indirect immunoperoxidase labeling revealed enzyme localization on or in the acinar cell secretory granule membrane and not in the surrounding cytoplasm. The luminal contents of the intercalated and striated ducts were also strongly positive. Stimulation of salivary secretion with phenylephrine or pilocarpine increased the amount of carbonic anhydrase in saliva. Acetatazolamide and potassium cyanate inhibited carbonic anhydrase activity. Reasons underlying the discrepancy between the histochemical and immunolabeling localization of carbonic anhydrase are discussed. It is concluded that the parotid acinar cells of mice appear to be a significant source of carbonic anhydrase in saliva but its role is enigmatic.

Allyl Alcohol-Induced Changes in the Rat Exocrine Pancreas

A histologic, histochemical and electron microscopic study was carried out on the rat exocrine pancreas 6-96 h after a single allyl alcohol intake. Histologically, acidophilia, necrosis and vacuolation of the pancreatic acinar cells were observed. Histochemically, a low but evident alcohol dehydrogenase activity could focally be demonstrated in the pancreatic acinar cell cytoplasm of the experimental and control rats. By electron microscopy, cytoplasmic lipid droplets, mitochondrial degeneration and necrosis were found in the acinar cells. Focal cytoplasmic degradation and vacuolation were seen in acinar, centroacinar and ductular cells of the pancreas. The findings are regarded as the consequence of the toxic action or acrolein that originates after allyl alcohol oxidation by alcohol dehydrogenase. Analogies between the liver and the pancreas in their response to acute allyl alcohol and chronic ethanol intake are discussed.

Quantitation of ultrastructural changes in mouse pancreatic acinar cells caused by foreign serum.

Quantitative changes in the pancreatic acinar cell organelles were studied in BALB/c mice injected with 1.0 ml fresh rabbit serum intraperitoneally. Groups of 5 mice were killed at 0, 1, 3, 6 and 12 h after the serum injection. Pancreatic tissue was processed for electron microscopy by glutaraldehyde and osmium tetroxide fixation and Epon embedding. The proportions of acinar cell cytoplasm (volume fractions) occupied by zymogen granules, granular endoplasmic reticulum, Golgi apparatus, mitochondria and lysosomes (including autophagosomes) were determined by the point counting method from electron micrographs. The volume fraction of lysosomes increased during the first 3 h and remained markedly elevated up to 12 h. The volume fractions of zymogen granules increased from 12 to 28% in 12 h. It was concluded that the secretory mechanism of pancreatic acinar cells was injured by the foreign serum. The injury caused accumulation of zymogen granules and increased autophagic activity in the acinar cells.

Ultrastructural changes in the pancreata of selenium-vitamin E-deficient chicks.

Three hundred and seventy 1-day-old male, white Leghorn chicks were divided into seven groups and fed a series of semipurified torula yeast diets either deficient in or supplemented with selenium and vitamin E. Chicks in each group were necropsied sequentially and the pancreata examined by light microscopy. Selected pancreata of selenium deficient chicks in various stages of the deficiency disease were examined by electron microscopy. Supplements of either selenium (0.2 mg/kg) or vitamin E (100 IU/kg diet) resulted in protection against pancreatic lesions. Changes in pancreata of selenium deficient chicks progressed from cytoplasmic vacuolation of acinar cell cytoplasm to focal disseminated acinar necrosis. There was ductular proliferation and interstitial fibrosis in advanced lesions. Acini around islets were less frequently affected than acini further away. Ultrastructurally, the mildest lesions were focal dilation of the endoplasmic reticulum and autophagic vacuoles in acinar cell cytoplasm. Necrotic areas contained both membranous and granular debris and fragments of intact endoplasmic reticulum. In fibrotic pancreata the main acinar cell changes were uniform dilation of endoplasmic reticulum and reduction in number of zymogen granules.

Biochemical and histochemical studies onp-nitrophenyl phosphate and ?-glycerophosphate hydrolysis at acid pH by rabbit parotid tissue

A biochemical and histochemical study has been made of the characteristics and distribution of acid phosphatases in the parotid gland of the rabbit. The substratesp-nitrophenyl phosphate and β-glycerophosphate have been used. Homogenate studies showed that substantial hydrolysis ofp-nitrophenyl phosphate occurred in the presence of tartrate and fluoride ions but that β-glycerophosphate hydrolysis was almost abolished by these additives. The pH optima usingp-nitrophenyl phosphate and β-glycerophosphate were found to be around pH 5.0 and pH 4.0 respectively. Studies on subcellular fractions revealed that maximalp-nitrophenyl phosphate hydrolysis occurred in the microsomal fraction whereas maximal hydrolysis of β-glycerophosphate occurred in the mitochondrial fraction. The histochemical staining patterns produced by the two substrates differed in several respects. Whenp-nitrophenyl phosphate was used heavy plasmalemmal staining occurred, while reactions using β-glycerophosphate as substrate produced heavy staining of the acinar cell cytoplasm including many of the zymogen granules. Both substrates resulted in the staining of lysosomes and certain vesicles associated with the Golgi complex. Formaldehyde fixation resulted in an overall reduction in staining intensity and glutaraldehyde fixation used in electron microscopic studies heavily inhibited much of the extralysosomal activity. The conclusion is reached that significant extralysosomal acid hydrolase activity is present in the rabbit parotid gland, much of which is located on smooth microsomes. The data is discussed in the context of the distribution of extralysosomal acid hydrolases and the staining patterns are considered in the light of the limitations inherent in the techniques employed.

The influence of thyroxine on the normal development of the pancreas in Rana pipiens larvae

AbstractComparative studies were made of the exocrine pancreas in normal, thyroidectomized, and thyroxine treated Rana pipiens tadpoles during various stages of development. The weight of the pancreas as milligram per cent body weight (mg% B.W.) is greatly reduced during both artificially induced and natural metamorphosis. During natural metamorphosis the reduction in mg% B.W. of the pancreas begins in the early larval stages and continues in a consistently decreasing pattern through the final stages with the maximum reduction (69%) occurring by the mid‐larval stages (XVI‐XX).In thyroxine treated tadpoles, reduction in mg% B.W. of the pancreas is directly proportional to hormone concentration and the relative weight of the gland is significantly less than that observed in any of the controls of equivalent limb stages even though the absolute weight of the gland has increased over that of the earliest stages (I–V). The pancreas of the thyroidectomized tadpoles showed no significant difference in mg% B. W. when compared to that of a normal control of equivalent limb stage range. Histological investigation of the pancreas revealed no evidence of widespread cellular necrosis of the exocrine elements. Some acinus disorganization, typified by large spaces in the connective tissues and a syncytial nature of the acinar cell cytoplasm, can be seen in the later stages. A discussion of the possible role of thyroid hormone in the normal development of the pancreas is presented. It is concluded that reduction in the mg% B.W. of the pancreas is a naturally occurring phenomenon during metamorphosis resulting from intestinal evacuation and water loss. The water loss may be influenced and regulated indirectly by thyroxine through an effect on cellular and subcellular membrane permeability.

The effect of methylation on basophilia.

A mixture of 0.05 N HCl and methanol is capable of completely inhibiting thionin and azure A metachromasia of intestinal mucin, cartilage and mast cell granules after treatment for 2 hours at 58°C. or 48 hours at room temperature. Slight reduction is noted after 2 weeks at 3°C. Cytoplasmic basophilia is completely destroyed after 4 hours of methylation at 58°C. or 48 hours at room temperature. Pancreatic acinar cell cytoplasm appears more resistant, requiring 8 hours at 58°C. and longer than 9 days at room temperature. Methylation at 3°C. is ineffective in inhibiting this basophilia even after 2 weeks. Nuclear and nucleolar basophilia with aniline dyes (azure A and thionin) requires 24 hours of methylation at 58°C. or 14 days at room temperature before there is complete destruction. There is no effect produced by methylation at 3°C. for 2 weeks. Alum hematoxylin staining of these structures is unaffected by the methylation procedure, indicating the different nature of action of this dye complex from the aniline dyes used. Reversal of the methylation procedure or demethylation can be accomplished with 0.5% KMnO4 for ½ hour at room temperature provided the methylation has not been too prolonged. Other oxidants such as periodic, peracetic and chromic acids as well as aqueous HCl and alkali (borax solution) fail to reverse the blockade. The substitution of 0.1 N HCl for the usual 0.05 N HCl in the methylation procedure brings about effective blockade in approximately ½ the time required by the 0.05 H NCl methanol. Despite the removal of cytoplasmic and nuclear basophilia by this method sections treated concomitantly and stained with the Feulgen nucleal procedure demonstrate strong Feulgen reactions indicating selectivity for the acid portion of the nucleic acid involved. Methylation after fixation of tissue in a chromate containing fixative (Zenker acetic) requires more prolonged treatment to inhibit cytoplasmic basophilia than is required after Formalin or 95% alcohol fixation. Otherwise the reactions occur similarly after either of the three fixatives. The positive periodic acid-Schiff reaction of colonic mucin, mixed tumor stroma and cartilage is completely inhibited by prior methylation for 96 hours at 58°C. and the reaction of gastric and small intestine mucins is only moderately reduced at this period. At room temperature no alteration is observed after methylation for 21 days. The positive reaction of human mast cell granules is abolished after 72 hours of treatment at 58°C. and is only moderately affected after treatment for 21 days at room temperature.