Selective staining of endocrine cells by basic dyes after acid hydrolysis

Ameliorative effects of jamun seed and orange peel extracts on microcystin LR induced alterations in calcitonin cells and parathyroid gland of rats

This study investigated changes in calcitonin cells (C-cells) and parathyroid glands (PTG) induced by microcystin LR (MCLR) exposure to rats and evaluated ameliorative effects of jamun (Syzygium cumini) seed (JSE) and orange (Citrus sinensis) peel (OPE) extracts. Wistar rats were treated as-Group A (control), Group B (MCLR), Group C (MCLR + JSE), Group D (MCLT + OPE), Group E (OPE) and Group F (JSE). Microcystin dose was (10 μg/kg body wt/day whereas OPE and JSE dose was 200 mg/kg body wt/day. Thyroid and PTG were fixed on 15 and 30 days following the treatment. C-cells of treated rats for 15 days with MCLR; MCLR + JSE and MCLR + OPE exhibit degranulation, mitochondrial swelling and prominent RER. In MCLR treated rats few cells completely lack secretory granules. After 30 days MCLR treatment accumulation of secretory granules and degeneration were noticed in C-cells. C-cell nuclear volume (NV) of MCLR, MCLR + JSE and MCLT + OPE treated rats show an increase. In MCLR, MCLR + JSE and MCLR + OPE treated rats PTG exhibit hyperchromatic nuclei, nuclear elongation and increased NV after 15 days. After 30 days MCLR treatment nuclei of PTG become more hyperchromatic, more elongated, show degeneration of nuclei and increase in NV. NV is increased in Group C and Group D. PTG remain unaltered 30 days following treatment with OPE and JSE. Microcystin LR provoke physiological effects on the blood calcium and alterations in C cells and PTG, which cause serious threat to organism. These changes can be protected by JSE and OPE.

Fine structure and cytochemistry of the mammalian pars intermedia

Various cytophysiological aspects of the pars intermedia of the pituitary are discussed. Cells containing melanocyte-stimulating hormone (MSH) have been studied under normal and experimental conditions. They react to variations in ionic equilibrium, but without any clear correlation with natraemia and osmotic blood pressure. The MSH-cell stimulation in hypernatraemic mice, which is not inhibited by bromocriptine, seems more specific than the stimulation in hyponatraemic mice, which is blocked by bromocriptine. The existence of a corticotropic cell system has been clearly demonstrated in the mouse (where it is particularly obvious), in the rat and in the cat but its significance is not clear. Although very poorly vascularized, the pars intermedia is rapidly invaded by tracer protein (horseradish peroxidase) injected either intravenously or intracerebroventricularly. The hypophysial cleft rapidly stores the tracer which can be resorbed by macrophagic epithelial cells lying free in the colloid contained in the cleft. Horseradish peroxidase lingers in the pars intermedia but is rapidly eliminated from the other hypophysial lobes after intraventricular (third ventricle) injection. Diffuse innervation of the pars intermedia applies to both glandular (MSH and ACTH) and non-glandular (epithelial and stellate) cells. While aminergic innervation of the pars intermedia is obvious, cholinergic innervation has not been demonstrated ultrastructurally or histochemically. Peptidergic fibres only occasionally penetrate marginal areas of the pars intermedia and seldom establish synaptic contacts with glandular cells. A specific relationship might exist between the pars intermedia and oxytocin fibres in view of the marginal distribution of the latter in the neural lobe. Numerous stellate cells of the pars intermedia react intensely with antiserum to gliofibrillar acid protein, indicating their astrocyte nature, which reinforces the idea of an analogy between the folliculo-stellate system of the hypophysis and the glial cells.

Mast Cells in the Salivary Glands and Tongue of the Ferret: Demonstration and Some Histochemical Observations

Previous investigations failed to demonstrate mast cells in the alimentary tract and extraparietal glands of the ferret. It was decided therefore to test this and assess factors that may be of influence. Major salivary glands and tongues of mature ferrets, which had been fixed in formalin-calcium, were examined by means of light microscopical histochemistry. Staining of paraffin sections with techniques depending on basic dyes or esterolytic activity was carried out for conventional times with and without previous oxidation, hot acid hydrolysis, and trypsin and beta-glucuronidase digestion. Aldehyde fuchsin and high iron diamine consistently revealed the presence of few mast cells in interstitial stroma of salivary glands and lingual musculature, and in the lamina propria of lingual mucosa. Alcian blue at 0.5 M MgCl2 and safranin produced less consistent results, and even fewer metachromatic mast cells were detected. No staining of mast cells was obtained with the technique for naphthol AS-D chloroacetate esterase. Pretreatment did not increase the numbers and/or staining reactions of mast cells. The results refute the previous misconception and suggest that ferret is a species with a low incidence of mast cells largely expressing a connective-tissue phenotype.

Neuroendocrine cell markers for pancreatic islets and tumors

The authors review the application of a variety of neuroendocrine cell markers to identify pancreatic islet cells and tumors. In the past, several empiric histochemical techniques had been used to demonstrate neuroendocrine cells, particularly the Grimelius argyrophilic stain. The development of immunohistochemistry made it possible to demonstrate specific cell products such as regulatory peptides, thus allowing the classification of pancreatic neuroendocrine tumors with a view to clinical symptoms. However, it is not always possible to visualize regulatory peptides in these tumors. It is therefore important to use broad-spectrum neuroendocrine cell markers to identify the neuroendocrine nature. These markers are proteins localized in the secretory granules (core- or membrane-related), in the cytosol, or in the cellular membrane. The markers most commonly used in routine histopathology are the secretory granule proteins chromogranin A and synaptophysin and the cytosolic enzyme neuronspecific enolase. Other new markers (e.g., synaptic vesicle protein 2) are of general diagnostic value. Region-specific antibodies to chromogranin A can be valuable in differentiating between benign and malignant neuroendocrine tumors. Some markers may be related to the functioning characteristics of pancreatic neuroendocrine tumors, such as prohormone convertases. In addition, markers giving further complementary information have been identified, such as five somatostatin receptor subtypes, the expression of which varies markedly in pancreatic neuroendocrine tumors. Antibodies against all somatostatin receptor subtypes are now commercially available, and immunohistochemical investigation of its expression should be routinely applied when considering treatment with somatostatin analogs.

Comparative histology of pulmonary neuroendocrine cell system in mammalian lungs

It is increasingly recognized that neuroepithelial endocrine cells and organoid clusters of these cells termed neuroepithelial bodies are widely distributed in the respiratory tract of vertebrates. This review focuses on the neuroepithelial endocrine system in the airway epithelium of mammals according to observations made in a wide range of species, as it appears in light and electron microscopy by means of various visualization techniques under normal and experimental conditions. Because there are similarities but also marked differences between species, wherever possible studies in human airways are emphasized. Conventional histochemical and ultrastructural studies including microspectrofluorimetry have demonstrated the amine-handling properties and the presence of neurosecretory granules in neuroendocrine cells of the epithelium of all mammals studies so far. The neuroepithelial bodies are innervated by morphological afferent- and efferentlike synaptic specializations. These, together with the presence of reciprocal synapses, emphasize that these cells may be involved in dual functions of chemoreception and secretion. Light and electron microscopic immunohistochemistry has demonstrated that neuroepithelial endocrine cells may contain various biogenic agents, suggesting that the neuroendocrine system is highly heterogeneous. Neural elements may interact in a complex manner, and the activation of certain neural pathways may control the release of biogenic substances to influence physiological airway functions. They may be particularly relevant in pulmonary diseases. Consequently, the function of this system is complex and it is highly probable that many of its aspects are still not elucidated.

Gastrointestinal endocrine tumours. Pathology

Neuroendocrine tumours can form in any part of the gastrointestinal tract. The most common types are the ECL cell tumours of the oxyntic mucosa of the stomach, G cell tumours of the duodenum, argentaffin, EC cell tumours of the small intestine and L cell tumours of the large bowel. The only well-defined clinical syndromes associated with hormone hypersecretion are ZES, resulting from duodenal gastrinomas, and carcinoid syndrome, caused by malignant argentaffin tumours. Genetic predisposition has been demonstrated for some tumour types, e.g. duodenal gastrinoma in MEN 1 and duodenal somatostatin cell tumours in MEN 2. Other factors predisposing to the genesis of these lesions include circulating hormone levels and the maintenance of chronic inflammatory states. As with most neuroendocrine tumours, malignant potential is difficult to assess on the basis of histology alone and prognostic evaluation depends more on size and evidence of local invasion and/or distant metastases.

Associations between lymphocytic thyroiditis, hypothyroidism, and thyroid neoplasia in beagles

The thyroids were evaluated in 276 control Beagles that were allowed to live out their full life span (mean = 12 years) in a closed breeding colony. Lymphocytic thyroiditis was found in 26.3% of the dogs. This lesion was characterized by lymphoplasmacytic inflammation accompanied by follicular destruction. The thyroiditis was progressive, resulting in severe atrophy of follicular tissue, and 44 dogs (15.9%) were diagnosed as hypothyroid at the time of death. In accordance with the experimental protocol, hypothyroid dogs were not given thyroxine replacement therapy. There was a high degree of heritability for the hypothyroidism. Hypothyroid dogs had an increased risk for thyroid follicular epithelial neoplasia and, in particular, for follicular adenocarcinomas. Twenty-four of the 44 hypothyroid dogs (54.5%) had one or more follicular thyroid neoplasms, whereas only 53 of the 232 (22.8%) clinically euthyroid dogs had similar tumors. Multiple thyroid tumors were present in 14 of the 44 (31.8%) hypothyroid dogs but in only 12 of the 232 (5.2%) euthyroid dogs. One or more follicular adenocarcinomas were present in 15 of the 44 (34.1%) hypothyroid dogs but in only 16 of the 232 (6.9%) euthyroid dogs. There was no difference in prevalence of hypothyroidism or tumors between the sexes. The strong association between progressive lymphocytic thyroiditis, hypothyroidism, and thyroid follicular neoplasia in these Beagles probably relates to promotion of residual follicular epithelium by chronic excess thyrotropin stimulation.

Effects of inhibin on rat gonadal differentiation and development in vitro

Previously we examined that inhibin-alpha subunit, transforming growth factor-beta 1 (TGF-beta 1) and epidermal growth factor (EGF) were expressed in sex-, cell- and stage-specific manners in perinatal rat gonads. To clarify effects of these growth factors on the rat gonadal differentiation and development, indifferent gonadal primordia with mesonephric tubules on gestational day 13 were cultured in vitro for 4 days in serum-free CMRL-1066 medium with inhibin, TGF-beta 1, EGF, anti-sera against these growth factors, testosterone or estradiol-17 beta, and then morphologically examined with reference to seminiferous tubule formation, germ cell division, Wolffian and Müllerian duct development. In male gonads, anti-inhibin-alpha serum suppressed the seminiferous tubule formation but inhibin, TGF-beta 1, EGF or steroid hormones did not affect on the tubule formation, germ cell proliferation nor gonoduct development. Seminiferous tubules in male gonads cultured in the medium containing anti-inhibin-alpha serum were incomplete and irregular in shape. On the other hand, in female gonads, inhibin suppressed the germ cell division and anti-inhibin-alpha serum led to the necrosis of germ cells, but other factors affected to neither sex cord formation nor germ cell division. Testosterone and estradiol-17 beta stimulated female Wolffian and Müllerian duct development, respectively. These results indicate that inhibin induces the seminiferous tubule formation and suppresses the female germ cell division in developing rat gonads in vitro.

Sertoli cells and testicular differentiation in the rat fetus

The fetal testis is not merely a precursor of the adult organ: it is indeed an endocrine gland whose function is the masculinization of the fetus. It differs physiologically and morphologically from the adult testis. In this paper, the first stages of testicular differentiation in the rat are described, with special emphasis on the ultrastructural aspects. At the stage of 13.5 days after fertilization, the first Sertoli cells differentiate; they are characterized by a voluminous and little electron dense cytoplasm, a well-developed RER formed by vesicles and short cisternae filled with a flocculent material. Progressively, they polarize and adhere to one another by adherens-like junctions and cytoplasmic interdigitations to form the differentiating seminiferous cords. In the basal part of the Sertoli cells, a mat of microfilaments differentiates under the plasmalemma, while cytoplasmic blebs protruding in the extracellular space tend to disappear. A continuous basal lamina delineating the seminiferous cords begins to appear on day 14.5 and becomes widespread on day 15.5. These observations, when compared with other data from the literature, emphasize the fact that the differentiation of the Sertoli cells is the first morphological event during testicular differentiation. A possible role of the Sertoli cells in the subsequent organogenesis of the testis is suggested.

Gut endocrine and neural peptides

The once exponential growth in the number of new gut endocrine peptides being discovered has become slightly slower in recent years, and expansion of the field of gut hormones has involved mainly the application of new investigative methods. Some new peptides have been described and major inroads have been made into establishing the ontogeny of gut endocrine cells, the origins and pathways of the enteric innervation, and the involvement of the diffuse neuroendocrine system as a whole in disease states. Further insight is being gained into the functional activity of the peptide cell system by studying the control, sites and rates of peptide gene expression, and the localization and characterization of peptide binding sites on target cells.

Morphology of the pineal gland in pregnant and nursing sows

The pineal glands of pregnant and nursing sows were studied by light and electron microscopy. Similar structural changes in the pineal gland during pregnancy and lactation were noted as follows: a proliferation of glial cells concurrent with a decrease in the number of pinealocytes, a relative increase in the number of pinealocytes with cytoplasmic accumulation of dense bodies, and an increase in number of presumptive microglia. It appears that pregnancy and lactation exert a complex influence on pineal function, with a predominantly stimulating effect.

Application of Grimelius argyrophil staining to the study of tumour ultrastructure. I. Effects of fixatives

Two methods have so far been proposed for staining samples by the argyrophil technique of Grimelius for electron microscopy. For Håkanson glutaraldehyde prevented argyrophilia, so the author stained sections from samples previously fixed by double formaldehyde/osmium tetroxide treatment and embedding. Vassallo used en bloc staining after fixation with glutaraldehyde-formaldehyde mixtures. We examined each factor which could directly interfere in argyrophil staining en bloc and on section. In the present experiment we compared effects of fixatives after staining en bloc. Glutaraldehyde prevented argyrophilia in 1 case out of 15, that of A-like cells in the oxyntic gland of the rat positivity was maintained in EC-like cells of this gland and adrenalin cells of the adrenal gland contrary to the previous description.

Giemsa stain applied to deplasticized sections to identify pancreatic islet cells

A new application of the Giemsa stain to demonstrate endocrine cells in deplasticized sections of Epon embedded material is described. Its application to the pancreas of Rana temporaria is illustrated. The technique does not require postfixation with OsO4 and is easily performed in 30 min. It allows the easy identification of three types of endocrine cells (A, B, and D). A cells, preferentially located at the islet periphery, stain purple-blue. B cells, which occupy the interior of the islet, display a lilac color. D cells give a strong purple color; they are located both in the periphery of the islets and scattered among acinar cells. Positive identification of the cell types was made by immunocytochemistry and electron microscopy.

Chromogranin A, B and C immunoreactivities of mammalian endocrine cells. Distribution, distinction from costored hormones/prohormones and relationship with the argyrophil component of secretory granules

Antibodies specific for chromogranin A, B or C have been used to detect immunohistochemically these three anionic proteins. Pancreatic A, B and PP cells, gut argentaffin EC, argyrophil ECL and gastrin G cells, thyroid C cells, parathyroid cells, adrenal medullary cells, pituitary TSH, FSH and LH cells as well as some axons of visceral nerves have been found to react with chromogranin A antibodies. Pancreatic A, gut EC and G, adrenal medullary and pituitary cells as well as some gut nerve fibers showed chromogranin B immunoreactivity. Chromogranin C immunoreactivity has been detected in pancreatic A, pyloric D1, intestinal L, thyroid C, adrenal medullary and pituitary cells, as well as in some gut neurons and nerve fibers. No crossreactivity has been found in immunohistochemical tests between chromogranins A, B or C and costored monoamines or peptide hormones/prohormones, from which chromogranins can be separated by selective extraction during fixation. On both morphological and chemical grounds a relationship seems to exist between chromogranin A and Grimelius' argyrophilia. Sialooligosaccharide chains of chromogranin A and, possibly, chromogranins' phosphoserine/phosphothreonine groups, seem to interact with guanidyl, amino, and/or imidazole groups of non-chromogranin components to form silver complexing sites accounting for granules' argyrophilia, which can be removed or blocked without affecting chromogranin immunoreactivities. The abundant anionic groups of the three proteins should contribute substantially to granules' basophilia, the partly "masked" pattern of which supports the existence of a close interaction of such groups with other components of secretory granules, including monoamines and peptide hormones or prohormones. Chromogranins could play a rôle in hormone postranslational biosynthesis and intragranular packaging.

Chromogranin: a newly recognized marker for endocrine cells of the human gastrointestinal tract

Existing methods for the histochemical demonstration of gastrointestinal cells are somewhat limited. Chromogranin represents a family of proteins that coexist with catecholamines in the secretory vesicles of adrenal medulla cells. In the present study, immunocytochemistry was used to test whether chromogranin is a marker for gut endocrine cells. Serial sections of each area of human gut were immunostained for chromogranin and for the amine and each of the peptides known to be present in mucosal endocrine cells. Chromogranin was immunostained in large numbers of endocrine cells in all tissues examined. All identified endocrine cell types were found, in serial sections or by sequential silver impregnations, to be chromogranin immunoreactive. However, the possibility exists that some chromogranin-immunoreactive cells contain a yet to be discovered endocrine substance. Immunostaining of chromogranin thus appears to provide a means for demonstrating all gastrointestinal mucosal endocrine cells identifiable by the methods described in this study.

Staining of different endocrine cells with hydrochloric acid-toluidine blue in Epon embedded rat tissue

The usual HCl-toluidine blue staining of different endocrine cells is applicable to paraffin embedded material. A modification for Epon embedded tissue suitable for consecutive light and electron microscopic studies is described which makes it possible to find the same stained cell, both in a semithin section and in subsequent ultrathin sections. This method facilitates the search for scattered specific endocrine cells. Without removing the resin, sections of Epon embedded tissues were hydrolyzed for 17 hr in 1% HCl at 65 C and stained for 2 hr in 0.1% toluidine blue in McIlvaine buffer, pH 5.8. The following cells were stained: C cells in thyroid glands; A and D cells in pancreatic islets; B cells in anterior pituitary; G, D and Ec cells in the gastrointestinal tract; Ad cells of the adrenal medulla.

Ultrastructural immunocytochemical localization of calcitonin in the C cells of the rat thyroid

Using unlabeled antibodies and peroxidase-anti-peroxidase complexes, calcitonin was localized at the ultrastructural level in rat thyroid C cells. Calcitonin was present mainly in secretory granules of the cells. A less intense positive reaction was noted in the cytoplasm surrounding the secretory granules.

Occurrence of different secretin-like cells in the digestive tract of the ascidian Styela plicata (Urochordata, Ascidiacea)

Secretin-like cells have been detected in the digestive tract of the ascidian Styela plicata by means of immunofluorescent and immunocytochemical methods. Especially, in the esophageal epithelium there are immunoreactive cells (S2) in which a biogenic amine (5-HT) and a regulatory peptide (secretin) occur together. In the gastric epithelium only secretin-like cells (S1) are present. Tests of cross-reactivity performed with glucagon, GIP and VIP, have confirmed the presence of a secretin-like molecule only in the S1 and S2 cells.

Ultrastructural and histochemical observations of neuroendocrine granules in nonneoplastic ovaries

Argyrophil and argentaffin cells are rarely seen in female genital tract structures. Their presence in normal, apparently healthy ovaries has not been reported until the present observation. Histochemical and ultrastructural studies demonstrated cells within the ovaries of two nonpregnant patients in the reproductive age that belong to the neuroendocrine or amine precursor uptake and decarboxylation (APUD) system. The lack of other discernible pathologic conditions suggests that these cells may be normal cellular constituents within the ovaries and lends support to the belief of a neural crest origin for primary ovarian carcinoid not associated with teratomatous or mucinous elements.

[The endocrine cells of the digestive system (author's transl)]

Endocrine cells occur in the digestive system as micro-organs (islets of Langerhans) or scattered throughout the epithelium of the gastrointestinal tract ("diffuse endocrine epithelial organ" of Feyrter). These gastro-entero-pancreatic (GEP) endocrine cells synthesize--in addition to serotonin--a great variety of polypeptide hormones, which regulate both carbohydrate metabolism and digestive processes. The present review deals mainly with cytology and cytochemistry of GEP endocrine cells. A synopsis is presented of the 19 endocrine cell types identified to date, which includes their update nomenclature and their anatomical distribution pattern. Morphological-functional aspects of cell biology, pathology, and cytogenesis of theses cells and their position within superimposed systems (APUD cells, paraneurons) are discussed.

Neuron specific enolase (NSE) immunostaining detection of endocrine cell hyperplasia in adult rats exposed to asbestos

Hyperplasia of endocrine cells in the lung of the adult rat exposed to asbestos has only been characterised so far by electron microscopy as there is a lack of reliable staining techniques for their demonstration at light microscopical level. Neuron specific enolase (NSE), an isoenzyme of the glycolytic enzyme enolase has recently been shown to be present in lung endocrine cells. In this study we reveal a marked endocrine cell hyperplasia at light microscopical level in the lungs of adult rats exposed to asbestos using antibodies to NSE. Very large groups of NSE-immunoreactive cells (20-80) were only observed in the lungs of rats exposed to asbestos for 12 months. In addition smaller groups of cells (2-10) known to be present normally and to decrease with age, were rarely noted in the controls but were frequently detected in the treated rats. Immunoreactive NSE is therefore a very good marker for endocrine cell hyperplasia and thus of early neoplastic changes.

An investigation into the origin and nature of 'amyloid' in a calcifying epithelial odontogenic tumour

Fresh and fixed tissue from a resection specimen of a calcifying epithelial odontogenic tumour (CEOT) was prepared for histological, histochemical, immunological and biochemical investigation in order to study the nature of the amyloid-like material. The fixed tissue gave positive reactions with Congo-red, Thioflavin T and the dimethylamino benzene (DMAB)-method for tryptophan. The diazotization-coupling (DC) method for tyrosine was negative. The major protein purified from the unfixed tissue by sequential gel filtration had a molecular weight of 9,800. The amino acid analysis of this protein had similarities with tuft enamel protein, immune amyloid and the variable light chain component (VK). From the data obtained in this study, it is not possible to determine the precise nature of the amyloid-like material in this CEOT. However, the results do support the concept that 'amyloid' should be considered as a term describing a broad group of related proteins.

An unusual bronchial carcinoid tumor: light and electron microscopy

An unusual bronchial carcinoid tumor was studied by light and electron microscopy. The tumor cells, which appeared to be monotonously uniform in hematoxylin and eosin stained sections, were found to be morphologically heterogeneous at the ultrastructural level with regard to the size, number, and morphology of the endocrine granules. Presumptive endocrine granules were seen in all tumor cells, but some cells contained only small round granules (2000 A largest diameter), other cells contained large round granules (some with as large a diameter as 1.0 mu), and some cells contained large polymorphic granules. Many of the cells stained positively at the light microscopic level when selective stains for endocrine cells were applied. All types of granules showed argyrophilia at the ultrastructural level. Numerous clusters of endocrine cells were observed in the otherwise normal bronchial and bronchial glandular epithelium. The spectrum of granule morphologies, as seen in the tumor cells, was displayed in cells of the intraepithelial clusters. Some mucous cells and sparsely ciliated cells within these clusters contained argyrophilic granules. Multiple continuities existed between the epithelial endocrine cell clusters and the underlying tumor mass. The intraepithelial clusters represent foci of carcinoma in situ, the genesis of which is discussed.

Increased serum and urinary calcitonin levels in patients with pulmonary disease

Serum and urinary calcitonin levels were measured in patients with acute and chronic inflammatory diseases of the lung. Using both carboxyl terminal and midportion antisera, the incidence of increased immunoreactive values of this hormone was 68 percent for patients with emphysema, 59 percent for tuberculosis, and 89 percent for acute bacterial pneumonitis. In order to determine the source of the high levels of calcitonin, immunoperoxidase stains were made of sections of human lung; the hormone was found within the bronchial Kultschitzky cell (K cell). This suggests a specific endocrine role for the K cell, and may explain not only the high calcitonin levels in patients with inflammatory lung disease, but also the high levels associated with both carcinoid tumor and small cell carcinoma, which may originate from K cells. It is apparent that moderately high levels of calcitonin in a patient with pulmonary disease cannot always be associated with tumor.

The staining of pancreatic delta cells for light microscopy

Three staining techniques--Hellerström-Hellman alcoholic silver nitrate, pseudoisocyanin, and the immunofluorescent technique for somatostatin--were compared to determine whether they are staining the same cell in the pancreatic islet of the rat. These comparisons were made by using staining and restaining procedures on the same islet. The results demonstrate that all three procedures stain the delta cell of the rat pancreatic islet. Some advantages of using pseudoisocyanin are discussed.

Histological and immunohistochemical studies of the endocrine cells of the gastrointestinal mucosa of the toad (Bufo regularis)

Using histological and immunhistochemical techniques, nine endocrine cell types were observed in the mucosa of the gastrointestinal tract of the toad, Bufo regularis, viz. enterochromaffin, somatostatin, glucagon, pancreatic polypeptide (PP), secretin, gastric inhibitory peptide (GIP), gastrin-C-terminal pentapeptide (GTPP), neurotensin and bombesin cells. The enterochromaffin cells were distributed throughout the gastrointestinal tract except the rectum. Somatostatin, glucagon, PP, secretin, GIP and GTPP cells were observed both in the stomach and in the small intestine. Neurotensin cells were seen only in the ileum and bombesin cells only in the pyloric and antral parts of the stomach. Immunostaining of consecutive sections did not reveal more than one polypeptide hormone in any of these cell types. It is concluded from the present results that the toad gastrointestinal mucosa contains endocrine cell types that are more or less homologous to those in the mammal alimentary tract, though some of them exhibit a different topographic distribution.

Immunohistochemical evidence of gastro-entero-pancreatic neurohormonal peptides of vertebrate type in the nervous system of the larva of a dipteran insect, the hoverfly, Eristalis aeneus

Using rabbit and guinea-pig antisera, raised against GEP neurohormonal peptides of mammalian origin, cells were observed in the brain and/or in the fused ventral ganglia of the last (fifth) larval instar of the hoverfly, Eristalis aeneus, being immunoreactive with antisera against insulin, somatostatin, glucagon, PP, secretin, gastrin/CCK/caerulein; substance P, enkephalin and endorphin. Most of these GEP neurohormonal peptides also occurred in nerve fibers. No immunoreactive cells or nerve fibers could be detected with antisera against GIP, VIP, (the central fragments of) CCK, bombesin or neurotensin. The antisera tested failed to reveal any immunoreactive cells or nerves in Weismann's ring (fused corpus allatum/corpus cardiacum and thoracic gland) or in different parts of the alimentary tract. The observations support the hypothesis that neuronal GEP hormonal peptide production in the brain is a genuinely original mechanism and the appearance of endocrine cells in the gut a later feature in evolution.

Gut hormones in Salamandra salamandra. An immunocytochemical and electron microscopic investigation

Histological, cytochemical and immunocytochemical methods were used in light and electron microscopical studies to demonstrate the presence of a neuroendocrine system in the gut of the urodele, Salamandra salamandra. Cytochemical stains capable of detecting peptide-producing endocrine cells demonstrate cells reacting with Masson's silver (argentaffin) method, Grimelius' argyrophil silver method, masked metachromasia method and the lead haematoxylin stain. Using antisera raised to a variety of mammalian gut peptides, cells containing bombesin-, gastrin-, somatostatin-, substance P- and glucagon-like immunoreactivity were indentified; vasoactive intestinal polypeptide- and substance P-like immunoreactivities were found in nerve fibres in the submucous and myenteric plexus. No immunoreactivity was detected from motilin, gastric inhibitory polypeptide, cholecystokinin or secretin. The ultrastructure of the immunoreactive cells and nerves was revealed by the semithin/thin method. All the cells indentified contained numerous electrondense secretory granules, which varied in their characteristic morphological structure from one cell type to another. The evidence collected in this study indicates that a complex neuroendocrine system regulating gut function is present in this amphibian and may have developed prior to the emergence of the phylum.

Intracytoplasmic fibrillary inclusions in bronchial carcinoid

A case of bronchial carcinoid with filamentous aggregates is described. The cytoplasmic inclusions were clearly demonstrated by means of Masson's trichrome stain in Bouin's fixed tissue, and the neoplastic cells showed a spontaneous green fluorescence with ultraviolet light. Electron microscopic examination showed that the inclusion bodies were composed of aggregates of filaments measuring 10A. They were located in the juxtanuclear region in close relation with mitochondria and the cisternae of the Golgi system. There were many neurosecretory granules inside the aggregates of filaments, some showing alterations in the dense core. From this data, we concluded that the aggregates seemed to represent an active rather than an involutional phenomenon and that their relation with hypoxemia and humoral influences needs further study.

Immunoreactivities of gastrin (G-) cells. II. Non-specific binding of immunoglobulins to G-cells by ionic interactions

Various gastro-entero-pancreatic (GEP) endocrine cells have been shown to contain concomitantly immunoreactivities against several peptide hormones. In the present study the "immunoreactivities" of gastrin (G-) cells of the rat stomach against 21 specific antisera and 10 control sera were investigated by means of the unlabelled antibody enzyme (PAP) technique using modifications of single steps in the immunocytochemical staining sequence. The results indicate that immunoglobulins can bind to gastrin cell granules obviously by non-specific ionic interactions. This non-specific binding of immunoglobulins occurs even in dilution ranges of the sera commonly used in immunohistochemical investigations of the GEP endocrine system. Since "adsorption controls" (preadsorption of the antisera with their respective antigens) will not discriminate between specific and non-specific binding of immunoglobulins to GEP endocrine cells additional specificity controls are necessary. In contrast to the immunostaining of various GEP endocrine cells by "established" antisera and of G-cells by gastrin antiserum immunoglobulins of sera from non-immunized animals as well as antibodies against corticotropin-lipotropin related peptides could be displaced from their binding sites in G-cells by alterations of the NaCl content of the buffers used as diluents or as rinsing solutions. To exclude immunostaining of GEP endocrine cells by nonspecific binding of immunoglobulins the following working procedures are recommended for immunocytochemical investigations of these cells: 1. Use of high titer antisera at low concentrations (diluted 1:1,500 or more). 2. Elevation of the salt (NaCl) content up to 0.5 M of the buffer used as diluent or as rinsing solution. 3. Adsorption controls will show reliable results only if point 1. and 2. have been taken into account.

Histochemical identification of fish ultimobranchial cells with polypeptide hormone producing APUD cells

This investigation is concerned with the possibilities to include the fish ultimobranchial cells in the polypeptide hormone producing APUD cell series because of the capacity of these endocrine cells to give positive reactions to visualize APUD cell system.

Complement-mediated unspecific binding of immunoglobulins to some endocrine cells

Unspecific binding of immunoglobulins to gastrin G cells, glucagon A cells and somatostatin D cells of the gastric mucosa or pancreas, as well as to the calcitonin-somatostatin cells of rabbit thyroid has been found to occur through a non antigen-antibody mechanism mediated at least in part by the C1q fraction of complement. The phenomenon represents a major drawback in hormone immunohistochemistry, which can be prevented by incubating the specific anti-hormone sera with anti-C1q antibodies or with complement-fixing immunocomplexes.