ON THE DEVELOPMENT OF THE ULTIMOBRANCHIAL GLAND IN AN ANURAN,RANA JAPONICA JAPONICA*

The development of the ultimobranchial gland (UBG) was studied from its earliest emergence in Rana japonica japonica. UBG primordia appear at stage 22 as outfoldings of the pharyngeal epithelium of the 6th visceral pouch in both sides of the body. At stage 24, they separate from the pharyngeal wall, and then become follicular at stage 25. During stages 27–30, which are just prior to metamorphic climax, the UBG seems to be activated, as shown by secondary follicle formation and pseudostratification of the follicle epithelium. At and after the completion of metamorphosis, the UBG shows a histological profile indicating low activity.     

Origin of cholinesterase-containing follicle cells and parafollicular cells of the developing thyroid gland in the rat

Summary The location of cholinesterase-containing cells in the thyroid gland and its precursors (median thyroid primordium and ultimobranchial bodies) has been investigated light-microscopically in rat embryos from the 13 to the 20th day of gestation.From the 13th to the 16th day of gestation the median thyroid primordium and the ultimobranchial bodies are distinct from each other. Cholinesterase-containing cells are found in both. On the 17th–18th day of gestation the reacting ultimobranchial cells spread into the median thyroid primordium where they take up a parafollicular position. At the 19th–20th day of gestation the distribution of cholinesterase-containing cells is as in the adult rat. The results seem to show that cholinesterase-containing follicular cells derive from the median thyroid primordium and cholinesterase-containing parafollicular cells from the ultimobranchial body.     

Similarities Between A.P.U.D. Cells and Monoaminergic Neurons: Evidence for a Dopamine Uptake Mechanism in C Cells of Chicken Ultimobranchial Gland

Abstract: The uptake of [³H]dopamine was studied in the C cells of chicken ultimobranchial gland (UBG). DA uptake appears to be an active and saturable mechanism (K_m= 8.6 μM). The C cells' affinity for DA is intermediate between dopaminergic synaptosomes and such extraneural tissues as platelets and heart. UBG incubation with DA leads to the synthesis of a noticeable quantity of DOPAC, indirectly showing the presence of MAO activity. Thus UBG C cells, besides having both an embryological derivation from the neural crest and some morphological aspects similar to synaptosomes, also possess an active uptake mechanism for a central neurotransmitter.     

Concomitant depletion of dopamine and secretory granules from cells in the ultimobranchial gland of vitamin D2-treated chicken

Summary The ultimobranchial gland (UBG) is a rich source of the polypeptide hormone calcitonin, which is present in a cell system analogous to the mammalian parafollicular cells (C cells) of the thyroid gland. Both types of cells are argyrophilic and, ultrastructurally, they are furnished with numerous electron-dense granules considered to contain the hormone. In the chicken, the main cells of the UBG contain large amounts of dopamine. The possible functional relationship between this amine and the hormone has been studied by a combination of fluorescence and electron microscopy of the UBG from chickens treated with vitamin D₂. This stimulus produced a depletion of dopamine and a pronounced degranulation of the UBG cells, concomitant with a loss in their argyrophilia. Administration of l-3,4-dihydroxyphenylalanine (l-DOPA) to vitamin D₂-treated animals was followed by a reappearance of dopamine in the cytoplasm of the UBG cells, whereas electron-dense granules or argyrophilia were not restored. It is suggested that this concomitant depletion of dopamine and the secretory granules from the UBG cells reflects a participation of the amine in the secretion of the polypeptide hormone.     

Ultimobranchial gland of the domestic fowl

Summary The ultimobranchial gland (UBG) of birds is particularly rich in calcitonin, the hypocalcaemic hypophosphataemic hormone, that is secreted by the C-cells of the mammalian thyroid. The principal cells of the UBG have a striking resemblance with the mammalian C-cells, i.e., they possess small intracytoplasmic dense-core secretory granules, 150–300 nm in diameter. The gland also contains a second, morphologically distinct, endocrine cell type with larger granules, 500–800 nm in diameter. A sensitive immunocytochemical reaction was developed with the use of antibodies against salmon calcitonin. By means of this technique the presence of calcitonin-immunoreactive molecules was demonstrated in both secretory cell types of the UB gland of the chicken. This gland can thus be considered as a homogeneous calcitonin-producing tissue. Whether the secretory products are identical is discussed and differences in the secretory pathways are suggested.     

Uptake and storage of indolamines in the ultimobranchial body of the fetal murine thyroid. 1-Autoradiographic histological study]

Incorporation of 3H-5 HTP is studied in ultimobranchial cells and thyroid cells of the mouse foetus from the 13th day to the 18th day of gestation. The APUD characteristics of these cells are first observed on the 14th day when the U.B. bodies are included in the thyroid anlage. The silver granules are then localized on the parafollicular cell cords from which C cells of the adult thyroid arize.     

Analysis of salmon calcitonin I in the ultimobranchial gland and gill filaments during development of rainbow trout, Oncorhynchus mykiss, by in situ hybridization and immunohistochemical staining

We have cloned two distinct cDNAs encoding salmon-type calcitonin (sCT)-I cDNAs from the ultimobranchial gland of rainbow trout, Oncorhynchus mykiss. Both cDNAs were predicted to encode nearly identical sCT-I precursors which consisted of an N-terminal peptide of 80 amino acid residues, a putative cleavage site Lys-Arg, sCT-I, a cleavage and amidation sequence Gly-Lys-Lys-Arg, and a C-terminal peptide of 18 amino acids. Development of sCT-I-expressing cells was then examined by employing conventional histochemical staining, in situ hybridization with a specific cRNA probe, and further immunohistochemistry. The primordium of the ultimobranchial gland was first identified, as two cell masses, in the region between the alimentary canal and sinus venosus behind the heart 17 days postfertilization (dpf; 14 degrees C). However, expression of sCT-I mRNA could not be detected in this gland until one day later, and appeared at 18 dpf. sCT-I immunoreactivity was first observed at 19 dpf (two days before hatching), and the ultimobranchial gland began to assume a follicular structure at 20 dpf (one days before hatching). As ontogeny proceeded, the sCT-I-immunoreactive cells increased in both number and stainability. The sCT-I mRNA was also expressed on the developing gill filaments, but immunoreactive sCT-I was not detected in these sites. These results provide basic data for further research on the organogenesis of the trout ultimobranchial gland.     

Ultimobranchial body and parathyroid gland of the parrot Psittacula psittacula in response to experimental hypercalcemia

Psittacula psittacula when subjected to long term hypercalcemia by intramuscular injections of vitamin D2 (20,000 I.U.) on alternate days and by increasing dietary calcium, exhibit a rise in the serum calcium level after 10, 20 and 30 days of treatment as compared to their corresponding controls. The ultimobranchial cells show progressive hypertrophy up to 20th day of the treatment. From 20th day till the end of the experiment (30 days) these cells show feeble staining response. The parathyroid glands suffer from degenerative changes due to its inactivity under chronic hypercalcemia.     

Unpaired Ultimobranchial Glands of the African Lungfish, Protopterus dolloi

The ultimobranchial glands of juvenile African lungfish (Protopterus dolloi) (14 individuals; total body length 25-205 mm) were immunohistochemically examined. In individuals larger than 36 mm, one ultimobranchial gland was close to the left afferent branchial arteries. The topography of the ultimobranchial gland was similar to that of salamanders and sharks, but not to teleosts. With body growth, the ultimobranchial gland was vascularized and the parenchymal cells were gradually immunostained with anti-calcitonin antibody. In all individuals examined, the ultimobranchial gland existed only on the left side of the pharynx. These observations are discussed from a phylogenetic viewpoint.     

Premature induction of amylase in pancreas and parotid gland of growing rats by dexamethasone

Studies were made on changes in the contents of α-amylase (EC 3.2.1.1) in the pancreas and parotid gland of rats during postnatal devlopment, on the premature induction of this enzyme by hormones and on the existence of specific glucocorticoid receptors in these tissues.The amylase content in the pancreas increased from the 9th day after birth and reached the adult level on the 28th day, its content in the parotid gland increased rapidly from the 16th to 28th day after birth and then rose more gradually to the adult level.Injection of dexamethasone into rats 6–8 days after birth induced increase in the amylase of the pancreas but not the parotid gland. However, injection of dexamethasone into weanling rats 21–23 days after birth resulted in precocious induction of amylase in both tissues.Specific glucocorticoid receptors were detectable in the parotid gland of rats from 6 days after birth but were almost undetectable in the pancreas until adolescence.     

Autoradiographic studies with 3H 1,25 dihydroxyvitamin D3 in thyroid and associated tissues of the neck region

Rats and mice fed a vitamin D-deficient or vitamin D-complete diet were injected with 3H 1,25 (OH)2 vitamin D3. Autoradiograms prepared from cross sections through the neck region revealed nuclear concentration of radioactivity strongest in parathyroid chief cells, occasionally in thyroid follicular epithelial and interfollicular cells, in the epithelium of tubular remnants of the ultimobranchial body, in epithelium of the esophagus, in chondrocytes of tracheal cartilage, and in myoepithelial cells of tracheal glands. In the thyroid, most of the follicle epithelial cells did not show nuclear concentration of radioactivity which occurred only occasionally and predominantly in follicles located in marginal positions. Thyroglobulin in lumina of thyroid follicles contained varying amounts of radioactivity that correspond to the diameter of the follicles, with relatively high amounts in large follicles and little or no radioactivity in small follicles. Competition with excess of unlabeled 1,25 (OH)2 vitamin D3 abolished nuclear radioactivity, but not the radioactivity in the colloid, while 25 (OH) vitamin D3 did not affect either. When a combination of autoradiography and immunohistochemistry was applied, follicular and parafollicular C-cells positive for calcitonin antibodies, did not show nuclear concentration of radioactivity. Tubular remnants of ultimobranchial bodies, however, showed distinct nuclear labeling, but did not stain, or only weakly stain, with antibodies to calcitonin. When 3H 25 (OH) vitamin D3 was injected, no nuclear concentration of radioactivity was noted in any of the tissues.(ABSTRACT TRUNCATED AT 250 WORDS)     

Innervation of the C cells of chicken ultimobranchial glands studied by immunohistochemistry, fluorescence microscopy, and electron microscopy

Innervation of the ultimobranchial glands in the chicken was investigated by immunohistochemistry, fluorescence microscopy and electron microscopy. The nerve fibers distributed in ultimobranchial glands were clearly visualized by immunoperoxidase staining with antiserum to neurofilament triplet proteins (200K-, 150K- and 68K-dalton) extracted from chicken peripheral nerves. The ultimobranchial glands received numerous nerve fibers originating from both the recurrent laryngeal nerves and direct vagal branches. The left and right sides of the ultimobranchial region were asymmetrical. The left ultimobranchial gland had intimate contact with the vagus nerve trunk, especially with the distal vagal ganglion, but was somewhat separated from the recurrent nerve. The right gland touched the recurrent nerve, the medial edge being frequently penetrated by the nerve, but the gland was separated from the vagal trunk. The left gland was innervated mainly by the branches from the distal vagal ganglion, whereas the right gland received mostly the branches from the recurrent nerve. The carotid body was located cranially near to the ultimobranchial gland. Large nerve bundles in the ultimobranchial gland ran toward and entered into the carotid body. By fluorescence microscopy, nerve fibers in ultimobranchial glands were observed associated with blood vessels. Only a few fluorescent nerve fibers were present in close proximity to C cell groups; the C cells of ultimobranchial glands may receive very few adrenergic sympathetic fibers. By electron microscopy, numerous axons ensheathed with Schwann cell cytoplasm were in close contact with the surfaces of C cells. In addition, naked axons regarded as axon terminals or "en passant" synapses came into direct contact with C cells. The morphology of these axon terminals and synaptic endings suggest that ultimobranchial C cells of chickens are supplied mainly with cholinergic efferent type fibers. In the region where large nerve bundles and complex ramifications of nerve fibers were present, Schwann cell perikarya investing the axons were closely juxtaposed with C cells; long cytoplasmic processes of Schwann cells encompassed large portions of the cell surface. All of these features suggest that C-cell activity, i.e., secretion of hormones and catecholamines, may be regulated by nerve stimuli.     

Effect of a calcium rich environment on the ultimobranchial gland of Rana tigrina.

Thirty two specimens of Rana tigrina were divided into four equal groups : group I = controls; group II = injected with Vitamin D2 and placed in a 0.8% aqueous solution of CaCl2; group III = injected with Vitamin D2 and kept in tap water; group IV = placed only in a 0.8% CaCl2 solution. The experimental specimens exhibited varying degrees of hyperactivity of their ultimobranchial gland. Specimens from all the groups were X-rayed. The experimental ones showed different intensity of calcium deposit in their paravertebral lime sacs. The results indicate that prolonged challenge of high calcium induces hyperactivity of the ultimobranchial gland to produce larger quantity of calcitonin, to counteract the experimental hypercalcemia.     

Premature induction of amylase in pancreas and parotid gland of growing rats by dexamethasone.

Studies were made on changes in the contents of alpha-amylase (EC 3.2.1.1) in the pancreas and parotid gland of rats during postnatal development, on the premature induction of this enzyme by hormones and on the existence of specific glucocorticoid receptors in these tissues. The amylase content in the pancreas increased from the 9th day after birth and reached the adult level on the 28th day, its content in the parotid gland increased rapidly from the 16th to the 28th day after birth and then rose more gradually to the adult level. Injection of dexamethasone into rats 6--8 days after birth induced increase in the amylase of the pancreas but not the parotid gland. However, injection of dexamethasone into weanling rats 21--23 days after birth resulted in precocious induction of amylase in both tissues. Specific glucocorticoid receptors were detectable in the parotid gland of rats from 6 days after birth but were almost undetectable in the pancreas until adolescence.     

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.     

Regeneration of the parathyroid glands after partial resection

By means of morphometrical methods, as well as by the method of volumetric reconstruction of the organs in 33 rats during 1-30 days regeneration of parathyroid glands have been studied after a simultaneous resection of the whole left and a half of the right gland. Total calcium content in blood serum in the experimental animals decreases on the 1st-2d day and normalizes by the 3d day. Regeneration of the remained part of the gland is realized at the expense of increasing mitotic activity and hypertrophy of parathyrocytes along the whole organ from the 3d up to the 13th day. There are no signs of the glandular parenchyma growth from the wound surface. On the 3d-5th day dividing parathyrocytes predominate in the half of the gland that adjoins the wound. This promotes a predominant longitudinal growth of the gland remnant and restoration of the organ's ellipsoid form on the 20th-30th day. The main pattern of the parathyroid gland restoration after its partial resection is regenerative hypertrophy.     

Effect of gamma irradiation on the efficacy of β-glucan against acetaminophen induced toxicity in mice

The present study was conducted to compare the efficacy of unirradiated β-glucan (UBG) and gamma irradiated β-glucan (GIBG) against acetaminophen (APAP) induced hepatotoxicity in mice. Mice of BALB/c strain were pretreated with UBG and GIBG (50 mg/kg, p.o.) for 7 days and on the 8th day they received an overdose of APAP (500 mg/kg, i.p.). Eight hours after the APAP injection, the levels of serum aminotransferase (AST) and alanine aminotransferase (ALT) were measured and liver, kidney and lung tissue were examined for morphological changes. A significant elevation (p < 0.001) of the levels of AST and ALT was observed in mice toxicated with APAP. Histology data revealed severe liver centrilobular necrosis, portal vein damage with apparent toxicity in renal glomerulus and lung inflammation associated with edema. However, a significant inhibition (p < 0.05) in the elevation of AST and ALT was observed in mice that received UBG and GIBG compared with APAP-treated mice. Histology examination revealed the non-statistical difference between the protective effects of GIBG and UBG against acetaminophen challenge. In conclusion, it was demonstrated that gamma irradiation induced no severe alteration in the protective activity of β-glucan against APAP-induced hepatotoxicity.     

Distribution,ontogeny and ultrastructure of somatostatin immunoreactive cells in the pancreas and gut

Summary Somatostatin cells are numerous in the pancreas and digestive tract of mammals as well as birds. In the pancreas of chicken, cat and dog they occur in both the exocrine parenchyma and in the islets. In the rat and rabbit, somatostatin cells have a peripheral location in the islets, whereas in the cat, dog and man the cells are usually more randomly distributed. In the stomach of rabbits and pigs, somatostatin cells are more numerous in the oxyntic gland area than in the pyloric gland area, whereas the reverse is true for the cat, dog and man. In the cat, pig and man, somatostatin cells are fairly numerous in the duodenum, whereas in the rat, rabbit and dog they are few in this location. In the remainder of the intestines somatostatin cells are few but regularly observed. Somatostatin cells are numerous in the human fetal pancreas and gut. In the fetal rat, somatostatin cells first appear in the pancreas and duodenum (at about the 16–17th day of gestation) and subsequently in the remainder of the intestine. Somatostatin cells do not appear in the gastric mucosa until after birth. Three weeks after birth, somatostatin cells show the adult frequency of occurrence and pattern of distribution. In the chicken, somatostatin cells are numerous in the proventriculus, absent from the gizzard, abundant in the gizzard-duodenal junction (antrum), infrequent in the duodenum and virtually absent from the remainder of the intestines. No immunoreactive cells can be observed in the thyroid of any species nor in the ultimobranchial gland of the chicken. In the chick embryo, somatostatin cells are first detected in the pancreas and proventriculus (at about the 12th day of incubation). They appear in the remainder of the gut much later, in the duodenum at the 16th day, in the antrum at about the 19th day and still later in the lower small intestine. The ultrastructure of the somatostatin cells was studied in the chicken, rat, cat and man; the cells were identified by the consecutive semithin/ultrathin section technique. The somatostatin cells display the properties of the D cell. There was no difference in granule ultrastructure between somatostatin cells in the gut and the pancreas. The granules, which are the storage site of the peptide, are round, supplied with a tightly fitting membrane and have a moderately electron-dense, fine-granulated core. The mean diameter of the somatostatin granules is smallest in rat (155–170 nm) and largest in the chicken (270–290 nm).     

Ultimobranchial body of Notopterus notopterus in relation to calcium and sodium rich environments

The UBB of Notopterus notopterus is a paired structure situated between the oesophagus and sinus venosus. Both right and left lobes of the gland are enveloped by a common thick connective tissue which gets constricted between the lobes and separates them. Numerous follicles of varying sizes are encountered in each gland. In N. notopterus the effects of hypercalcaemia (caused by keeping the specimens in 0.5% of CaCl2 solution and by injecting 4000 I.U. of vitamin D2 on alternate days) on UBB has been observed. The effects of NaCl rich environment (created by keeping the fish in 0.5% NaCl solution) on this gland has also been studied. In the UBB of N. notopterus the activity of the gland is observed in terms of: 1. increase in the blood supply of the gland and the dilation of the blood vessel, 2. increase in the height of the follicular epithelium, 3. cytoplasmic hypertrophy resulting in the increase in secretory processes, 4. appearance of pseudostratified epithelium in place of single layered cuboidal follicular epithelium and 5. nuclear and cellular hypertrophy. According to these characteristics it is evident that the gland from group II shows gradual activity from the 2nd day onwards and is maximum on the 6th day. From 8th day to the close of the experiment gradual inactivity of the gland is discerned--follicles get atrophied and the cells appear in clumps. The gland from group III shows a good response to its environment and is more hypertrophied as compared to that of group II. The activity of the gland closely parallels serum sodium levels which increase up to the 8th day when UBB shows the maximum activity. The serum sodium level rises from a normal of 110 m eq/l to a peak of 180 m eq/l on 8th day. After 10 days onwards the gland shows gradual inactivity and degeneration. The serum sodium level is 130 m eq/l on 12th day. These observations support the view that the main role of UBB in N. notopterus lies in sodium metabolism and it is only partially responsible for calcium regulation.     

瘟病病毒感染对三角帆蚌主要消化器官的影响

通过人工感染实验,在感染三角帆蚌瘟病病料组织后第3、5、7、9、11 d,运用光学显微镜和电子显微镜分别观察了三角帆蚌(Hyriopsis cumingii)主要消化器官的病理变化特征.结果表明,三角帆蚌瘟病病毒(H.cumingii Plague Virus,HcPV)严重破坏了三角帆蚌消化器官的结构.主要消化腺肝损伤最为严重:光镜下,攻毒7 d内腺管肿大,管腔缩小,7 d后腺管细胞空泡化并形成多核体;电镜下,线粒体、内质网等细胞器结构破坏,病毒粒子增殖速度快.消化道的病理变化主要表现为胃、肠结构的破坏,胃肠基本结构及感染病毒后的病理变化相似:光镜下,攻毒7 d内胃肠结构变化不大,7 d后柱状细胞肿大,纤毛脱落,并伴有上皮细胞的脱落;电镜下,细胞器结构破坏,甚至空泡化,病毒粒子前期增殖较慢,后期增殖较快,但总体增殖速度比肝慢.