A simple impregnation technique for thin and semithin enterochromaffin cells in sections

Application of Grimelius argyrophil staining to the study of tumour ultrastructure. III. Effects of osmium tetroxide

The results obtained in electron microscopy for Grimelius (1968) argyrophil staining by the en bloc staining of Vassallo and the staining on section of Håkanson were compared on tumoral and non-tumoral tissue samples and were found to lead to different results. Our earlier results for the en bloc staining method indicated that the fixative used in this process was important and that embedding in resin followed by staining of section weakened silver impregnation. We examined here the effects of OsO4 post-fixation combined with such embedding and found that staining was obtained within a shorter period and was more intense. This staining on section was not specific enough, since it was observed in secretory granules of non-argyrophil cells such as those containing somatostatin. In addition, this staining was not confined to specific peripheral zone as it occurred after en bloc staining; particularly in secretory granules with double structure including a core such as those containing glucagon in the pancreas or certain granules in tumoral carcinoid tissue. Consequently silver deposits were located both in the core and peripheral zone of such granules. Moreover, after OsO4 post-fixation, embedding in resin, and staining on section, argentaffin and argyrophil properties intermingle.

Neuroendocrine differentiation in prostatic carcinoma

Specimens from 53 cases of prostatic carcinoma obtained during total prostatectomy or transurethral resection of prostate were analyzed for neuroendocrine differentiation with immunocytochemical tests for serotonin, neuron-specific enolase, and chromogranin as well as with the Churukian-Schenk argyrophil reaction. Forty-seven per cent (25 of 53) of the prostatic carcinomas were positive for neuroendocrine differentiation, usually with an overlapping combination of these techniques. Nine per cent (five cases) contained areas with numerous neuroendocrine cells, 11 per cent (six cases) had focal scattered neuroendocrine cells, and 26 per cent (14 cases) had rare neuroendocrine cells. The positive cases spanned the histologic spectrum of prostatic adenocarcinoma; histologically none resembled a carcinoid tumor or a small cell carcinoma. Positive cases were further studied with a battery of antisera to 12 polypeptide hormones. Immunoreactivity to only bombesin (one case) and calcitonin (two cases) was detected. In five cases, neuroendocrine differentiation was studied by electron microscopy and verified at the ultrastructural level.

Endocrine-paracrine (APUD) cells of the human female urethra and paraurethral ducts

The distribution, immunostaining profile and ultrastructural morphology of human female urethral and paraurethral endocrine-paracrine (APUD) cells was studied. Five urethras obtained from radical cystectomy specimens were stained with antisera to serotonin, neuron-specific enolase, chromogranin, bombesin, calcitonin, somatostatin, prostatic acid phosphatase, prostatic specific antigen and with the Churukian-Schenk argyrophil method. Numerous endocrine-paracrine cells were observed along the entire length of resected urethra, with these cells most numerous in the paraurethral ducts. The endocrine-paracrine cells were positive for serotonin, neuron-specific enolase, chromogranin and the argyrophil reaction. Scattered bombesin and very rare calcitonin immunoreactive cells were noted. The endocrine-paracrine cells were of the open (luminal extensions) and closed cell types and often had multiple long dendritic processes suggesting a primarily paracrine function. By electron microscopy the secretory granule morphology was highly variable. Autonomic innervation of endocrine-paracrine cells was noted. The relationship of female urethral and paraurethral endocrine-paracrine cells to those of the male prostate and urethra is discussed with speculation as to the functional role these cells may play.

Light microscopic histochemistry on plastic sections

As compared with conventional paraffin, celloidin, and frozen sections, semithin plastic sections offer a superior quality of the light microscopic image in terms of better resolution, absence of distortion and shrinkage artifacts, and suitability for calcified tissues. Application of histochemical methods to such sections often encounters, however, serious difficulties resulting from a considerably reduced reactivity of plastic-embedded biological material. Factors involved include a poor penetration of reagents into plastic embedding media due to a steric or hydrophobic hindrance, as well as a blockade of the reactive chemical groups in the sample due to interactions with fixatives and plastics. Embedding in polar (hydrophilic) plastics, such as glycol methacrylate, permits carrying out a large number of histochemical reactions, including the demonstration of enzymatic activities, directly on sections, but is less suitable for combined light/electron microscopic studies because of an imperfect ultrastructural preservation of tissues. Embedding in nonpolar epoxy resins, particularly if combined with a double aldehyde-osmium fixation, results in a high quality ultrastructure but almost fully inhibits the histochemical reactivity of the embedded material. In order to restore this reactivity, i.e. to unmask chemical groups bound by the polymerized resin, semithin epoxy sections require the removal of the embedding matrix by alkoxides prior to the histochemical procedure. Additional steps are also often necessary: treatment of osmium-fixed sections with oxidative agents, e.g., hydrogen peroxide or periodate which reoxidize the bound osmium and remove it from tissue, and a controlled proteolytic digestion, especially useful in immunocytochemical studies, which probably cleaves the bonds between the primary aldehyde fixative, and the reactive sites. This article reviews histochemical methods which have been successfully applied to plastic-embedded material. Using polar methacrylates and/or nonpolar epoxy resins as embedding media, it has been possible to demonstrate proteins and aminoacid residues, carbohydrates, lipids, nucleic acids, biogenic amines, inorganic ions, and some enzymes, although the spectrum of methods found as suitable for plastic-embedded material is far narrower than that available for paraffin or frozen sections.(ABSTRACT TRUNCATED AT 400 WORDS)

Quantitative autoradiography, electron microscopy, and granulometry of endocrine cells in the rabbit colon

A high-resolution autoradiographic study was conducted on 268 thin sections of endocrine cells in the rabbit colon following injection of (3H) L-dopa. Using quantitative autoradiography, silver-proteinate impregnation, granulometry, and statistical analysis of cell populations by the Falck procedure, three cell types were identified--EC, L; and H--as well as a single cell with distinct ultrastructural characteristics. For the first time, a fine quantitative estimation of the handling ability of amine precursor related to the cross-sectional areas of each cell type was obtained, using a Kontron Digiplan image analyzer. All cells studied showed the ability to take up the precursor. Labeling indices were 6.63, 2.15, and 2.14 for EC, L, and H, respectively. These data and silver-proteinate impregnations provide good criteria for differentiating EC from H cells despite morphological similarities. After critical analysis of granule diameters, L cells were considered to be pluripotential in secretory activity.

Application of the thiocarbohydrazide method for vicinal glycol group detection to the study of gastric mucosa endocrine cells

The thiocarbohydrazide-silver proteinate (TCH SP) method was applied to the study of cat, rabbit and mouse gastric mucosa endocrine cells. After 24-h treatment with thiocarbohydrazide (TCH), glycogen was seen in the hyaloplasm of X, D, P, A and O cells but not in EC, EC-like or D1 cells. With flotation times as short as 30 to 40 min glycogen was readily detected in X cells. Secretory granules of EC cells were constantly stained, while those of D1 cells failed to react. In most experiments granules of X, A and O cells showed peripheral "staining", while in others staining of variable intensity affected the entire granular cross-section in X, D and P cells. With 72-h exposure to TCH, EC and EC-like cells showed particles resembling glycogen, even staining or only peripheral staining of certain EC cell granules. From the results of this and previous studies, EC cell staining is believed to be due wholly or partly, according to exposure times, to the action of silver proteinate, while that of certain non-EC cells is probably a specific indicator of complexed carbohydrates.