Expression and localization of prohormone convertase PC1 in the calcitonin-producing cells of the bullfrog ultimobranchial gland.

We examined the expression and localization of the prohormone convertases, PC1 and PC2, in the ultimobranchial gland of the adult bullfrog using immunohistochemical (IHC) and in situ hybridization (ISH) techniques. In the ultimobranchial gland, PC1-immunoreactive cells were columnar, and were present in the follicular epithelium. When serial sections were immunostained with anti-calcitonin, anti-CGRP, anti-PC1, and anti-PC2 sera, PC1 was found only in the calcitonin/CGRP-producing cells. No PC2-immunopositive cells were detected. In the ISH, PC1 mRNA-positive cells were detected in the follicle cells in the ultimobranchial gland. No PC2 mRNA-positive cells were detected. RT-PCR revealed expression of the mRNAs of PC1 and the PC2 in the ultimobranchial gland. However, very little of the PC2 mRNA is probably translated because no PC2 protein was detected either by IHC staining or by Western blotting analysis. We conclude that the main prohormone convertase that is involved in the proteolytic cleavage of procalcitonin in the bullfrog is PC1.

A morphological and immunohistochemical study of the ultimobranchial body in the Japanese lizard and the snake.

A morphological and immunohistochemical study of the ultimobranchial body of reptiles Japanese lizard and snake was carried out. The ultimobranchial body of the Japanese lizard was located adjacent to the left arch of the aorta between the trachea and esophagus. It was found as a cluster or group of cells with no capsule. Grimelius' silver impregnation and lead-hematoxylin staining produced positive reactions in some of the clustered cells and follicular cells. The same reaction pattern was observed with anti-calcitonin using the PAP method. The PAP reactions were positive to antiserum against pig calcitonin, but negative to antiserum against synthesized human calcitonin. Furthermore, the PAP reactions were negative to antiserum against tyrosine hydroxylase. The immunofluorescent study of the snake ultimobranchial body revealed that most of the clustered cells and some of the follicular cells were calcitonin-immunoreactive but none was tyrosine hydroxylase-immunoreactive. Certain histological similarities exist between the Japanese lizard ultimobranchial body and snake ultimobranchial body, but the distribution of calcitonin-positive cells were slightly different. In the Japanese lizard, the positive cells were scattered between the foliicles and the number was small. However, most of the cells which formed the cluster in the ultimobranchial body of snake were positive. The findings suggest that the configuration of amino acid in the Japanese lizard calcitonin and snake calcitonin are similar to that of pig calcitonin, and the reptile and the birds is a boundary of the tyrosine hydroxylase existence.

Localization of nitrergic neuronal and non-neuronal cells in the ultimobranchial glands of the chicken.

The ultimobranchial glands of 20 chickens, aged 2-3 months, were investigated for their nicotinamide adenine dinucleotide hydrogen phosphate-diaphorase (NADPH-d) reactivity and the distribution of nitric oxide synthase (NOS), using NADPH-d histochemistry and NOS immunocytochemistry respectively. Formazan, the blue reaction product of NADPH-d, was localised in the neuronal cell bodies and nerve fibres. Most of the cell bodies were found in the parenchyma. Some of them occurred in the wall of the ultimobranchial cysts, and a few in the immediate vicinity of the blood vessels. Labelled nerve fibres mostly travelled with blood vessels, while few of them appeared in the cystic lining. In addition to neuronal profiles, some C cells, cystic lining, and vascular endothelium were also labelled. NOS staining was found in neuron-like cells and fibres that were confirmed as neurons in adjacent sections stained with antibodies against neuron-specific enolase. It was also detected in cystic lining and in some C cells, but not in vascular endothelium. The distribution patterns of NADPH-d and NOS suggest that NO may play a role in the regulation of the secretory activity of and the blood flow through the ultimobranchial glands.

Fine structure of the ultimobranchial cysts in the thyroid of the adult guinea pig.

The ultimobranchial cysts in the thyroid of the adult guinea pig are identified by a cytochemical method. The ultimobranchial tissue has the shape of an irregular cyst, with non-specific esterase activity that is resistent to HgCl2 inhibition. The TEM reveals five different types of epithelial cell in the cyst wall: 1. cells with deeply invaginated nuclei and of varying shape, from flat to cylindrical but most of them cuboidal. 2. Mucous cells that are tall and similar to goblet cells. 3. Tall cells with big granules that have a dense core. 4. Ciliated cells similar to those in the respiratory tract. 5. C-cells crowded with the small dense granules typical for the cell type. The cyst is enveloped by rather coarse collagen fibers and many wide sinusoids.

Observations on the fine structure, enzyme histochemistry, and innervation of parathyroid gland and ultimobranchial body of Chthonerpeton indistinctum (Gymnophiona, Amphibia).

Fine structural and enzyme histochemical observations on ultimobranchial body and parathyroid gland of the caecilian Chthonerpeton are presented. The cell clusters and follicles of the ultimobranchial body consist mainly of granulated cells which are termed C-cells and obviously belong to the APUD cell series. In the larger follicles additional possibly exhausted degranulated cells and replacement cells occur. A rich supply of nerve fibres has been found in this gland. Frequently nerve terminals were observed to come into synaptic contact with the C-cells. Two categories of nerve fibres occur: a) fibres containing large polymorphic electron dense granules (probably purinergic fibres), b) fibres containing small electron transparent vesicles and a few electron dense granules (probably cholinergic fibres). The parathyroid gland consists of elongated cells (one cell type) poor in organelles and often containing fields of glycogen and lipid droplets. The cells are further characterized by fair amounts of lysosomal enzymes; they are interconnected by maculae adhaerentes and occludentes. No nerves and blood vessels have been found in the parathyroid gland of Chthonerpeton.