Ultrastructural immunocytochemical localization of LH and FSH in the pituitary of the untreated male rat

Summary Rapid freeze-substitution fixation was employed in immunocytochemical studies on the localization of LH and FSH in the typical gonadotrophs of the anterior pituitary in the untreated male rat; a modification of a recently described ferritin antibody method (Inoue et al. 1982) was used in these studies. It was shown that rapid freeze-substitution fixation provides good preservation not only of the ultrastructure but also of the antigenicity. Both LH and FSH were clearly demonstrated in the same gonadotrophic cells, but the subcellular localization of these gonadotrophins differed: (i) LH was mainly located in small secretory granules, 250–300 nm in diameter; (ii) FSH was mainly present in large secretory granules, up to 500 nm in diameter. In the pituitary gland of the adult male rat, all gonadotrophs that react to antibodies against gonadotrophins are characterized by small and large secretory granules. Other types of cells of the anterior pituitary containing either small secretory granules or resembling corticotrophs with secretory granules assembled at cell periphery did not react to either anti-LH beta or anti-FSH beta serum.For light microscopy, the peroxidase antibody method was used. All of the gonadotrophin-positive cells contain both LH and FSH. None of the pituitary cells reacted to antibody against only one gonadotrophin. However, some cells are LH-rich while other cells are FSH-rich.     

Immunocytochemical mapping of gastrin/CCK-like peptides in the neuroendocrine system of the blowfly Calliphora vomitoria (Diptera)

Summary The distribution of gastrin/CCK-like immunoreactive material has been studied in the retrocerebral complex of Calliphora. The material reacts with antisera specific for the common COOH terminus of gastrin and CCK but not with N-terminal antisera. The three thoracic ganglia and the fused abdominal ganglia each contain a specific number of symmetrically arranged immunoreactive cells both dorsally and ventrally in pairs on either side of the midline in a sagittal plane. The neuropil of these ganglia also contains a considerable amount of immunoreactive fibres and droplets. Reconstructed axonal pathways suggest that some of the nerve fibres have their origins within the brain and/or the suboesophageal ganglion. Immunoreactive material may also be seen apparently leaving the thoracic ganglion posteriorly via the abdominal nerves, and there is strong evidence of a neurohaemal organ within the dorsal sheath in the region of the metathoracic and abdominal ganglia. There appears to be a direct correlation between the content of peptidergic material of cells and fibres and the age and diet of the flies. The corpus cardiacum contains COOH-terminal specific gastrin/CCK-like material within the intrinsic cells and in the neuropil. It is present also in the cardiac-recurrent nerve entering the corpus cardiacum anteriorly and in the nerves leaving the gland dorsoposteriorly, the aortic or cardiac nerves. It is not observed, however, in the nerves leaving the corpus cardiacum ventroposteriorly, the so-called oesophageal, gastric or crop-duct nerves. The corpus allatum and the hypocerebral ganglion do not contain immunoreactive material of this type. Gastrin/CCK-like and secretin-like immunoreactive materials appear to co-exist in the cells of the corpus cardiacum and co-existence of gastrin/CCK-like and pancreatic polypeptide like substances occurs within certain cells of the thoracic ganglion.     

Vascular morphology of the bovine spermatic cord and testis

Summary The highly coiled testicular artery within the bovine spermatic cord has a constant luminal diameter but a continuously decreasing mural thickness. The pampini form plexus is composed of three interconnected venous networks differing in mesh sizes and calibres. The large veins of the first network display pouches and permanent constrictions, which may serve as throttle devices. The constitutents of the third network are venules or venous capillaries with diameters between 10 and 20 m; they favor a periarterial position or even occupy the media-adventitia border of the testicular artery. All plexus veins are devoid of valves. The existence of true arteriovenous anastomoses between smaller branches of the testicular artery and plexus veins was established by serial sections. The vascular morphology of the spermatic cord is discussed with special attention to a postulated venous-arterial steroid transfer in this region.Supported by the Deutsche Forschungsgemeinschaft and the Stiftung zur Förderung der wissenschaftlichen Forschung an der Universität Bern     

Choline acetyltransferase- and peptide immunoreactivity of submucous neurons in the small intestine of the guinea-pig

Summary The peptides cholecystokinin (CCK), neuropeptide Y (NPY), somatostatin (SOM), substance P (SP) and vasoactive intestinal peptide (VIP), and the synthesizing enzyme for acetylcholine, choline acetyltransferase (ChAT) were localized immunohistochemically in nerve cell bodies of the submucous ganglia in the small intestine of the guinea-pig. VIP-like immunoreactivity was found in 45% of submucous neurons. ChAT immunoreactivity was observed in a separate group of nerve cells, which made up 54% of the total population. There were three subsets of neurons immunoreactive for ChAT: (1) ChAT neurons that also contained immunoreactivity for each of the peptides CCK, SOM and NPY, representing 29% of all submucous neurons; (2) ChAT neurons that also contained SP-like immunoreactivity, representing 11% of all submucous neurons, and (3) ChAT cells that did not contain any detectable amount of the peptides that were localized in this study.     

Association of gap junctions with endoplasmic reticulum in rat parotid glands

Summary Examination of the parotid gland of the rat has shown specific associations of cisterns of the endoplasmic reticulum with gap junctions. About 20% of the junctions are so intimately associated with cisterns of the endoplasmic reticulum that in freeze fractured material the cisternal membranes remain attached to the junctional membrane faces, obscuring most of the junctional array except for a thin ring of telltale particles. This association was seen only in the parotid gland of the rat, but not that of the other species examined.     

Sex differences in adrenocortical structure and function

Summary Adrenal glands of adult male hamsters are larger and secrete more cortisol than those of females. Stereology was therefore used to study zonal and cellular aspects of development of the adrenal cortex of male and female hamsters. Adrenal glands were studied at weekly intervals from day 21 to day 77 of postnatal ontogenesis. Within this period, body weight did not differ significantly between the sexes. During development, absolute and relative adrenal weights were higher in males; their zona glomerulosa (ZG), zona fasciculata (ZF) and zona reticularis (ZR) become markedly larger than those in females. No marked changes in the volume of individual ZG cells occurred although ZF cells and ZR cells become larger in male than female animals. The total number of adrenocortical cells increased within the period studied, a greater increase being observed in ZG and ZF in males. No distinct sex difference was observed in the number of ZR cells throughout development. From day 56 of postnatal life the adrenal cortex of male hamster contained more parenchymal cells than the female gland. These results thus indicate that sex differences in hamster adrenal cortex depend upon changes in number and size of parenchymal cells.Supported in part by a grant from the Committee of Zoology, Polish Academy of Sciences     

Catecholamine-containing pancreatic islet cells of the domestic fowl

Summary In an attempt to identify pancreatic islet cells emitting formaldehyde-induced fluorescence (FIF), the pancreatic islets of the domestic fowl were studied by combined fluorescence, ultrastructural, silver-impregnation and immunohistochemical methods in the same section or in consecutive semi-thin and ultra-thin sections. The results indicate that islet cells emitting intense FIF exhibit a strongly argyrophil reaction with the Grimelius' silver method and also immunohistochemical reaction with anti-glucagon serum, but not with anti-5-HT serum. Therefore, the fowl islet A cell, a peptide hormone-producing cell, stores simultaneously catecholamine as biogenic amine. The islet B and D cells did not display any FIF, any argyrophil reaction with the Grimelius' silver method, or any immunoreactivity with anti-glucagon or anti-5-HT sera. The fluorescent but non-argyrophil cells dispersed in the exocrine acinus may well be PP cells.     

Interaction of metabolic inhibitors with actin fibrils

Summary The dependence of the arrangement of fibrillar actin in cultured endothelial cells on metabolic conditions was investigated with cellular elements derived from the heart of Xenopus laevis tadpoles. Either primary culture or an established cell line (XTH-2) were used in these studies The metabolic stage of the cells was influenced by inhibiting respiration and lactate production. The actin pattern was revealed either by indirect immunofluorescence or by tetramethylrhodaminyl (TRITC)-phalloidin fluorescence. Total block of energy supply causes in all cases a distinct loss of actin fibrils, while inhibition of respiration alone increases the variability of actin organization. In primary XTH cells but not in XTH-2 cells cyanide disintegrates most of the actin fibres during 3 h of treatment. This effect is independent of the inhibition of respiration, since actin gels prepared from skeletal muscle also undergo destruction in the presence of cyanide. It is concluded that the actin fibrils of the primary cells and the established line behave differently to changing metabolic conditions and to application of KCN.     

Ultrastructural immunocytochemical evidence for peptidergic neurotransmission in the pond snail Lymnaea stagnalis

Summary Three neuronal systems of the pond snail Lymnaea stagnalis were immunocytochemically investigated at the ultrastructural level with the unlabeled peroxidase-antiperoxidase technique. Preliminary electrophysiological and cell-filling investigations have shown that a cluster of neurons which reacts positively with an antiserum against the molluscan cardio-active peptide FMRFamide, sends axons to the penis retractor muscle. In this muscle anti-FMRF-amide (aFM) positive axons form neuro-muscular synapses with (smooth) muscle fibers. The morphological observations suggest the aFM immunoreactive system to be involved in peptidergic neurotransmission. In the right parietal ganglion a large neuron (LYAC) is penetrated by aFM positive axons which form synapse-like structures (SLS) with the LYAC. The assumption that the SLS represent the morphological basis for peptidergic transmission is sustained by the observation that iontophoretical application of synthetic FMRFamide depolarizes the LYAC. The axons of a group of pedal anti-vasopressin (aVP) positive cells run in close vicinity to the cerebral ovulation (neuro-)-hormone producing cell system (CDC system) Synapses or SLS between the two systems were not observed. The fact that (bath) application of arg-vasopressin induces bursting in the CDC, may indicate that the vasopressin-like substance of the aVP cells is released non-synaptically.     

Cellular and subcellular distribution of iron in the lamina propria of rat duodenum

Summary Cellular and subcellular distribution of iron in the lamina propria of rat duodenum was studied after a single i.p. injection of iron dextran, using electron microscopy and peroxidase cytochemistry. X-ray spectrum microanalysis was used for positive identification of iron. Ironcontaining particles (IP) were found in the cytoplasm of three cell types, viz. macrophages, pericytic reticular cells and sheathing fibrocytes. IP-containing organelles in lamina propria cells were more heterogeneous compared to absorptive cells and, in addition, some differences were noted in the subcellular distribution of IP in the 3 cell types. A common denominator in these 3 cell types was the presence of endogenous peroxidase, also shared by Kupffer cells which are known to be involved in iron storage. Peroxidase activity was absent in absorptive epithelial cells. It is hypothesized that the cells of the lamina propria, like Kupffer cells, may be the site of storage of excess iron absorbed, releasing iron upon demand and migrating into the lumen to prevent iron overload. In this fashion they may regulate the exchange of iron with the environment. The presence of peroxidase in these as well as Kupffer cells, and its absence in absorptive cells also raises the possibility that this enzyme may be related to certain aspects of iron storing process.