Ultrastructural changes in dog thyroid follicular cells elicit by concanavalin A in vitro

Summary Dog thyroid follicular cells exposed to concanavalin A (Con A) in vitro showed changes in cell shape, induction of colloid droplets and alterations in the distribution of microvilli. Cells exposed to Con A plus suboptimal concentrations of TSH (thyroid stimulating hormone) showed pseudopods and their cytoplasm was virtually occupied with colloid droplets. This findings suggest that Con A potentiated pseudopod and colloid droplet formation induced by TSH.Acknowledgments. The authors gratefully acknowledge the expert technical assistance of J. M. Greco. Supported by V. A. Research Funds.     

An Ig-A-like substance in the chicken's pineal

Summary Immunohistochemistry revealed an Ig-A-like substance on the luminal surface of the pineal follicles and in the parafollicular layer. This substance was observed around 1 week of age and disappeared by 8 weeks at the time when the transformation of the follicular pattern leads to an adult-type pineal tissue.     

An Ig-A-like substance in the chicken's pineal

Immunohistochemistry revealed an Ig-A-like substance on the luminal surface of the pineal follicles and in the parafollicular layer. This substance was observed around 1 week of age and disappeared by 8 weeks at the time when the transformation of the follicular pattern leads to an adult-type pineal tissue.     

A new biological activity for the neuropeptide FMRFamide: experimental evidence for a secretagogue effect on amylase secretion in the scallopPecten maximus

FMR Famide immunoreactivity in the digestive tract of the bivalve molluscPecten maximus was investigated by immunocytochemistry. Positive FMRFamide-like immunoreactivity was detected in nerve fibres in close contact with exocrine α amylase secreting cells. Physiological studies on enzymatically dissociated cells of the stomach-digestive gland complex demonstrated the involvement of FMR Famide and analogues in the control of α amylase release from the cells. The FMRF Famide-induced secretion was shown to be time- and dose-dependent. In contrast to most naturally occurring vertebrate secretagogues which are hormones, FMRFamide appears to work in our in vitro system as a paracrine factor.     

Bovine pituitary intraglandular colloid fraction F5 localized in the rat endocrine pancreas

Bovine pituitary intraglandular colloid thought to be a waste product, is the holocrine secretion of intermediate lobe cells. It is housed in the intraglandular lumen (residual lumen) and is extruded into the venous circulation of the cavernous sinuses via clefts in the capsule of the gland aligned with the intraglandular lumen. Intraglandular colloid, fraction F5 (mol.wt 34,000), radiolabeled with (125I)Na and injected (0.15 ml) into the right internal jugular vein of male Wistar rats, accumulated in the endocrine pancreas. Autoradiographs showed that the material had specifically localized in the capillary network of the endocrine pancreas. Since the intermediate lobe is poorly vascularized, intraglandular colloid is considered to be the transport medium for intermediate lobe materials.     

Bovine pituitary intraglandular colloid fraction F5 localized in the rat endocrine pancreas

Summary Bovine pituitary intraglandular colloid thought to be a waste product, is the holocrine secretion of intermediate lobe cells. It is housed in the intraglandular lumen (residual lumen) and is extruded into the venous circulation of the cavernous sinuses via clefts in the capsule of the gland aligned with the intraglandular lumen. Intraglandular colloid, fraction F₅ (mol.wt 34,000), radiolabeled with (¹²⁵I)Na and injected (0.15 ml) into the right internal jugular vein of male Wistar rats, accumulated in the endocrine pancreas. Autoradiographs showed that the material had specifically localized in the capillary network of the endocrine pancreas. Since the intermediate lobe is poorly vascularized, intraglandular colloid is considered to be the transport medium for intermediate lobe materials.This study was supported by a grant from the Natural Sciences and Engineering Research Council of Canada.I would like to thank S. Choles and J. Bennett for their technical expertise with the help of P. Galvin and W. Halina. I thank members of the Central Animal Facilities, McMaster University Medical Centre, Hamilton, Ontario, for labeling the intraglandular colloid and for counting the decay rate of the tissue. I would also like to thank Drs. A. deBold and J. Kraicer, Faculty of Medicine, Queen's University, Kingston, Ontario, for their interest in this study.     

An immunohistochemical and ultrastructural comparison of the effects of 2-bromo-alpha-ergocryptine on intrasellar and transplanted rat pituitaries.

Following 2 weeks of administration of 2-bromo-alpha-ergocryptine, a marked decrease was observed in prolactin immunoreactivity of the grafted pituitaries, whereas no reduction was noted in the intrasellar pituitaries. No evidence of crinophagy was revealed by electron microscopy in prolactin cells of 2-bromo-alpha-ergocryptine-treated rats.     

Presence of "pancreatic polypeptide" cells, and gastrin immunoreactivity in immuno-induced exocrine pancreas carcinoma]

1) In electively immuno-induced carcinomas of the exocrine pancrease in Mice, where A (glucagon) and B (insulin) endocrine cells persist, cells with a pancreatic polypeptide immunoreactivity are also detected, even in late evolution stages. These cells, like D cells, containing somatostatin, are localized only in the pancreatic remains surrounding the anaplasic carcinomatous tissue: islets, adenomatous parenchyma, and ductular epithelium. Ultrastructure of these cells shows their active elaboration of numerous chracteristic secretion granules. (2) Immunocytoenzymatic detection of gastrin is negative in the exocrine and endocrine pancreatic tissues. However one of the anti-gastrin sera used gives a positive reaction, in some carinomatous cells only. Does this immunoreactivity characterize a polypeptide specific to the pancreatic carcinomatous cell?     

Localization of substance P-like immunoreactivity in Hydra.

Substance P-like immunoreactivity was found in Hydra attenuata mainly but not exclusively in the nerve and interstitial cells, localized in the cytoplasm and on the cell surface membranes.     

Immunocytochemical demonstration of contractile cells in the human ovarian follicle

Summary Actin-and myosin-like immunoreactivity is found in cells located in the theca externa of the follicle wall of the human ovary, and corresponding to previously observed myoid cells. The immunocytochemical observation provides direct structural evidence that non-vascular contractile cells are also present in the follicle wall in humans. As expected, perifollicular blood vessels showed a positive immunoreaction for actin and myosin in their smooth muscle walls.This work was supported by the Swedish Medical Research Council, grant No. 14X-732/5680.     

Immunocytochemical demonstration of contractile cells in the human ovarian follicle

Actin- and myosin-like immunoreactivity is found in cells located in the theca externa of the follicle wall of the human ovary, and corresponding to previously observed myoid cells. The immunocytochemical observation provides direct structural evidence that non-vascular contractile cells are also present in the follicle wall in humans. As expected, perifollicular blood vessels showed a positive immunoreaction for actin and myosin in their smooth muscle walls.     

Preliminary observations on the co-existence of regulatory peptides in cells of the baboon endocrine pancreas

Summary Immunocytochemical procedures at ultrastructural and light microscopy level revealed, in the Chacma baboon endocrine pancreas, cells which were immunoreactive for glucagon and pancreatic polypeptide (PP). Some D cells were observed to contain secretory granules with both the appearance and immunoreactivity of A cell secretory granules.     

Preliminary observations on the co-existence of regulatory peptides in cells of the baboon endocrine pancreas

Immunocytochemical procedures at ultrastructural and light microscopy level revealed, in the Chacma baboon endocrine pancreas, cells which were immunoreactive for glucagon and pancreatic polypeptide (PP). Some D cells were observed to contain secretory granules with both the appearance and immunoreactivity of A cell secretory granules.     

Localization of brain type creatine kinase in kidney epithelial cell subpopulations in rat

Summary Immunoperoxidase studies of rat kidney using antibody to brain type isoenzyme of creatine kinase (BB) revealed a specific staining in the epithelial cells of the thick ascending limb of the Henle's loop and collecting tubule. Occasional epithelial cells in cortical tubules that lack brush border were also positive for BB. Renal glomeruli and proximal tubules showed no immunoreactivity to this enzyme.     

Localization of brain type creatine kinase in kidney epithelial cell subpopulations in rat

Immunoperoxidase studies of rat kidney using antibody to brain type isoenzyme of creatine kinase (BB) revealed a specific staining in the epithelial cells of the thick ascending limb of the Henle's loop and collecting tubule. Occasional epithelial cells in cortical tubules that lack brush border were also positive for BB. Renal glomeruli and proximal tubules showed no immunoreactivity to this enzyme.     

Physical methods for characterization of microbial surfaces

There are different concepts for explaining the adsorption of microorganisms to solid surfaces: the DLVO theory and the surface free energy. Basic aspects of both theories are discussed. Established methods for determining the surface properties of microbial cells are reviewed: Electrophoretic mobility, colloid titration, electrostatic interaction chromatography, bacterial adherence to hydrocarbons, partitioning in an aqueous two-phase system, hydrophobic interaction chromatography, contact angle measurement and X-ray photoelectron spectroscopy. They are discussed and classified according to their potential for the correlation of cell surface characteristics and adsorption behavior.     

NDRG2 is highly expressed in pancreatic β cells and involved in protection against lipotoxicity

The N-myc downstream-regulated gene 2 (NDRG2) is involved in cell differentiation and apoptosis, but its function in the pancreas remains to be established. Herein we examine the expression and function of NDRG2 in the endocrine pancreas. NDRG2 immunoreactivity was localized mainly in the cytoplasm of pancreatic β cells. When β-TC3 cells were exposed chronically to high levels of free fatty acid (FFA), cell viability was impaired, and Akt and NDRG2 phosphorylation were reduced. NDRG2 is a potential substrate of protein kinase Akt. Overexpression of constitutively active Akt enhanced NDRG2 phosphorylation and abolished the apoptosis induced by FFA in β-TC3 cells, whereas NDRG2 knock-down attenuated Akt-mediated protection of β cells against fatty acid-triggered apoptosis. Collectively, these data indicate that NDRG2 acts as a key molecule in pancreatic β cells and is involved in the Akt-mediated protection of β cells against lipotoxicity.     

Releasable GABA in tubular epithelium of rat kidney

The distribution of gamma-aminobutyric acid (GABA) in the rat kidney was examined by immunocytochemical techniques. GABA-like immunoreactivity (GABA-LI) was predominantly confined to the renal tubules, including the ascending parts of the distal tubules, and the loops of Henle, the collecting tubules and ducts, and the connective parts of the convoluted tubules. In GABA-positive cortical tubules, about half of the epithelial cells were labelled. The labelled cell type showed the ultrastructural features of principal cells. Depolarizing stimulation by ouabain and high K+ concentration evoked the efflux of endogenous GABA from kidney slices. The present findings, along with previous results, suggest that GABA released from renal tubular epithelium, and transported with the urine, might be involved in the modulation of contractility in the urinary tract.     

The relationship of intraglandular colloid production to hormone synthesis

Summary The production of intraglandular colloid, brought about by the cyclic breakdown of intermediate lobe cells, is related to the synthesis of hormones in the hypophysis. By analyzing the shift of the amino acid, cystine, during various phases of the gland's cycle it is apparent that hormones, as well as other protein determinants of immunological importance, are transported by way of the intraglandular cleft to the venous circulation and to the cerebrospinal fluid.This study was supported by a grant from the National Research Council of Canada.     

Releasable GABA in tubular epithelium of rat kidney

Summary The distribution of gamma-aminobutyric acid (GABA) in the rat kidney was examined by immunocytochemical techniques. GABA-like immunoreactivity (GABA-LI) was predominantly confined to the renal tubules, including the ascending parts of the distal tubules, and the loops of Henle, the collecting tubules and ducts, and the connective parts of the convoluted tubules. In GABA-positive cortical tubules, about half of the epithelial cells were labelled. The labelled cell type showed the ultrastructural features of principal cells. Depolarizing stimulation by ouabain and high K⁺ concentration evoked the efflux of endogenous GABA from kidney slices. The present findings, along with previous results, suggest that GABA released from renal tubular epithelium, and transported with the urine, might be involved in the modulation of contractility in the urinary tract.