The kidney,adrenocortical homolog,and corpuscles of Stannius in the cockscomb pricklebackAnoplarchus purpurescens

The morphology of the kidney, adrenocortical homolog, and the corpuscles of Stannius was examined in the cockscomb prickleback,Anoplarchus purpurescens, a marine teleost which inhabits the intertidal zone. The paired kidneys of this fish are fused throughout most of their length, there is essentially a single posterior cardinal vein on the right side, they possess renal corpuscles, and there is no distal segment of the tubule. The tubule is specialized, in descending order, into ciliated neck and two proximal segments before entering the system of collecting tubules and ducts. The cells of the latter system are specialized for mucous secretion, as are cells of the main excretory ducts, the paired archinephric ducts. Tubulogenesis occurs in the kidneys in close apposition to the archinephric ducts. The presumptive adrenocortical homolog is located around the posterior cardinal veins in the head kidney while paired corpuscles of Stannius are confined to the posterior end of the kidney. All of the above features are consistent with those found in the kidneys of many other marine teleosts.     

Gross,histological and ultrastructural morphology of the aglomerular kidney in the lined seahorse Hippocampus erectus

Histologic evaluation of the renal system in the lined seahorse Hippocampus erectus reveals a cranial kidney with low to moderate cellularity, composed of a central dorsal aorta, endothelial lined capillary sinusoids, haematopoietic tissue, fine fibrovascular stroma, ganglia and no nephrons. In comparison, the caudal kidney is moderately to highly cellular with numerous highly convoluted epithelial lined tubules separated by interlacing haematopoietic tissue, no glomeruli, fine fibrovascular stroma, numerous capillary sinusoids, corpuscles of Stannius and clusters of endocrine cells adjacent to large calibre vessels. Ultrastructural evaluation of the renal tubules reveals minimal variability of the tubule epithelium throughout the length of the nephron and the majority of tubules are characterized by epithelial cells with few apical microvilli, elaborate basal membrane infolding, rare electron dense granules and abundant supporting collagenous matrix.     

Electron microscopic studies of the corpuscles of Stannius of an airbreathing teleost (Heteropneustes fossilis)

The ultrastructure of the corpuscles of Stannius (CS) ofHeteropneustes fossilis reveals a homogenous cellular composition characterized by only one cell type, with large secretory granules and abundant ribosomal endoplasmic reticulum. These cells are comparable to the type 1 cell described in the CS of other teleosts; type 2 cells, whose presence is ubiquitous in the CS of freshwater species are absent inH. fossilis. Our data on the CS ofH. fossilis demonstrate that not all freshwater species possess type 2 cells in their CS and these are not essential for life in freshwater.     

Fine Structure of the Adrenocortical Homolog and the Corpuscles of Stannius of Amia calva L.

A comparison is made between the fine structure of yellow corpuscles and white corpuscles located within the kidneys of the holostean fish, Amia calva L. The yellow corpuscles are composed of epithelial cells possessing all the features of steroid-producing tissues, namely an abundance of vacuoles, tubular smooth endoplasmic reticulum, and mitochondria with tubular cristae. The Golgi apparatus is also a conspicuous component of their cytoplasm. These cells are homologous to adrenocortical cells of higher vertebrates and they have cytoplasmic projections which extend into the lumina of surrounding sinusoids. The white corpuscles possess epithelial cells of variable appearance but all cells contain secretory granules and an extensive rough endoplasmic reticulum. The secretory granules appear to originate at the Golgi apparatus and occasionally are observed intact in the intercellular space. However the method of release of these granules was not clearly defined. These corpuscles are similar to the corpuscles of Stannius which have been described in modern bony fish. The presence of multivesicular bodies and smooth endoplasmic reticulum in some cells may reflect the origin of the corpuscles of Stannius from the tubular nephron. A. calva appears to be a suitable organism for comparative studies into the function of the adrenocortical homolog and corpuscles of Stannius in “primitive” fish.     

The corpuscles of Stannius in arawana (Osteoglossum bicirrhosum), an ancient teleost

The corpuscles of Stannius of arawana (Osteoglossum bicirrhosum), an ancient teleost, were examined by routine light and electron microscopy and following their immunoreactivity to salmon and trout stanniocalcin antisera. Periodic acid-Schiff positive cells of the corpuscles of Stannius had a follicular arrangement and demonstrated a strong immunohistochemical reaction with both stanniocalcin antisera. Fine structural analysis of the paired, posteriorly located, and perirenal ovoid glands revealed two morphologically distinct cell types the basal laminae of which were ramified by nerve terminals. Immunocytochemistry demonstrated that osmiophilic secretory granules in both cell types were immunoreactive to the stanniocalcin antisera. When extracts of arawana corpuscles of Stannius were subjected to sodium dodecyl sulphate electrophoresis and Western blot analysis a diffuse molecular weight band was evident ( approximately 68 kDa) in the non-reduced condition. In all cases, immunoreactivity was abolished by preabsorption of the antisera with salmon stanniocalcin or with a crude extract of arawana corpuscles of Stannius. The corpuscles of Stannius of arawana are similar to those in more recent teleosts with respect to cell structure and their anatomical distribution but their stanniocalcin is more similar in molecular weight to that present in at least one other non-teleost actinopterygian (the gar) which has an ancient lineage.     

Vascularization,innervation, and ultrastructure of the endocrine cell types of stannius corpuscles in the teleost Gasterosteus aculeatus

The blood circulation of the Stannius corpuscles, like that of the kidneys to which the corpuscles are attached, represents a portal system. The corpuscles receive blood from the dorsal caudal vein and from a vein coming from the hypaxial musculature. They are drained by veins which enter the caudal parts of the kidneys and therefore endocrine substances released by the corpuscles pass through the kidneys before they enter the general body circulation. The corpuscles are penetrated by sympathetic nerves coming from a small subvertebral ganglion. It is likely that these nerves innervate the muscular coat around the blood vessels. The muscular coat surrounding the renal blood vessels, the collecting tubules and part of the ureters, is innervated by nerves from the same ganglion. The secretory activity of the gland cells appears to be controlled by blood borne factors, because neither synaptic contacts with these cells, nor gap junctions among the cells, have been found in thin sections and freeze-etch replicas of the corpuscles. The corpuscles contain two cell types, both presumed to have endocrine function. Histochemical and ultrastructural data indicate that the gland cells produce glycoproteins. It is likely that the contents of the secretory granules are released by exocytosis. One cell type is structurally similar to the cells described in many other teleosts and thought to be engaged in the synthesis of a hypocalcemic hormone. The ultrastructure of the second cell type resembles cells described only in other migratory species: salmonids and eels. It may be involved in the control of monovalent ions.     

Cytoarchitecture of the corpuscles of Stannius in hillstream teleosts, Barilius bendelisis (Ham.) and Garra gotyla (Gray)

The teleosts, Barilius bendelisis and Garra gotyla possess corpuscles of Stannius (CS) which are discrete, encapsulated bodies lying in close proximity to the mesonephros. The corpuscular cells are arranged in anastomosing cords which are separated from each other by connective tissue septa and numerous sinusoids. Light microscopically, 2 types of secretory cells comprise the CS in these species. Majority of the corpuscular cells are stainable with AF and PAS in contrast to the nonstainable cells which evince little affinity for the dyes. The fine cytoplasmic granules contained in the stainable cells are polarized on the vascular face in Barilius bendelisis.     

Stanniocalcin-like immunoreactivity in the corpuscles of Stannius of the bowfin Amia calva L.

Summary We used an antiserum against salmon stanniocalcin in an immunohistochemical, immunocytochemical, and Western blot analysis of bowfin (Amia calva) corpuscles of stannius. The bowfin is one of two extant holostean species with ancient ancestral links to modern-day bony fishes. The corpuscles of Stannius (white corpuscles) of the bowfin were scattered throughout much of the kidney among the adrenocortical homolog (yellow corpuscles) but could be distinguished from the adrenocortical homolog by their positive staining with both the periodic acid-Schiff reaction and a salmon stanniocalcin antiserum. Immunoreactivity was confined to cytoplamic granules and was absent when the antiserum was blocked with salmon stanniocalcin or with a crude extract of bowfin corpuscles of Stannius. When bowfin corpuscle-of-Stannius extracts were subjected to sodium dodecyl sulphate electrophoresis and Western blot analysis, two closely spaced bands were evident (43–45 kDa). Staining of both bands was abolished by pre-absorption of the antiserum with salmon stanniocalcin. In comparison to salmon stanniocalcin, the reputed bowfin hormone migrated faster in gels, suggesting a smaller apparent size. The purification of bowfin stanniocalcin should yield important new information regarding the evolution of this unique calcium-regulating hormone.     

On the fine structure of corpuscles of Stannius of the eel,Anguilla japonica

Summary The Stannius corpuscle of the eel (Anguilla japonica) consists of numerous ovoid or polymorphic lobules separated by loose connective tissue containing blood capillaries. Each lobule is composed of a number of columnar secretory cells, containing numerous secretory granules, and arranged more or less radially. Each secretory granule, spherical, 0.5–1.0 in diameter, and osmiophilic, is surrounded by a limiting membrane derived from the Golgi membrane. The well developed rough-surfaced endoplasmic reticulum is closely associated with the Golgi field. Some Golgi elements might also be intimately associated with the outer nuclear membrane. Numerous glycogen particles are distributed throughout the cytoplasm. The secretory granules which tend to accumulate near the basal part of the cell might be released into the loose connective tissue. From these facts, the corpuscles of Stannius are considered to be protein-secretory endocrine glands without any similarity to the adrenal gland.     

鸡肾发生的组织学观察

采用组织学方法和电镜技术,对9个不同发育时期的鸡(Callus domestiaus)胚胎进行了观察.通过对鸡胚胎肾组织发生过程的观察,探讨鸡胚中肾的发生与退化,后肾的发生、分化规律和特点.结果表明,孵育到第16期在中肾前端附近出现一些中肾小泡.孵育到第18期形成中肾小管.孵育到第26期,中肾小管的盲端内陷,原始的肾小囊和肾血管球形成,中肾小管显著伸长并迂回曲折.孵育到第33～37期,体前后部中肾组织均已形成完整的肾单位.第37～46期体前部至后部的中肾组织依次退化.孵育到第26期从泄殖腔附近发出的输尿管芽向生后肾组织侵入生长,生后.肾组织产生许多生后肾小泡.第33期出现肾小囊和肾小管,肾小管伸长并发生折叠,出现集合小管、近端小管和远端小管的形态分化.第37～46期肾小体逐渐发育成熟,肾小管继续分化出现细段.鸡的中肾具有排泄功能.鸡后肾的发生与分化存在明显的时间差异.肾单位的分化中,同一胚龄肾组织内可存在不同发育阶段的肾小体,集合小管分化较早,诱导近端小管和远端小管分化,细段分化较迟.     

Studies of gonadal sex differentiation

Gonadal differentiation has a determinative influence on sex development in human embryos. Disorders of sexual development (DSD) have been associated with persistent embryonal differentiation stages. Between 1998 and 2015, 139 female patients with various (DSD) underwent operations at the Scientific Center of Obstetrics, Gynaecology and Perynatology in Moscow, Russia. Clinical investigations included karyotyping, ultrasound imaging, hormonal measurement and investigations of gonadal morphology. The male characteristics in the embryo are imposed by testicular hormones. When these are absent or inactive, the fetus may be arrested at between developmental stages, or stay on indifferent stage and become phenotypically female. A systematic analysis of gonadal morphology in DSD patients and a literature review revealed some controversies and led us to formulate a new hypothesis about sex differentiation. Proliferation of the mesonephric system (tubules and corpuscles) in the gonads stimulates the masculinization of gonads to testis. Sustentacular Sertoli cells of the testes are derived from mesonephric excretory tubules, while interstitial Leydig cells are derived from the original mesenchyme of the mesonephros. According of the new hypothesis, the original mesonephric cells (tubules and corpuscles) potentially persist in the ovarian parenchyma. In female gonads, some mesonephric excretory tubules regress and lose the tubular structure, but form ovarian theca interna and externa, becoming analogous to the sustentacular Sertoli cells in the testis. The ovarian interstitial Leydig cells are derived from intertubal mesenchyme of the mesonephros, similar to what occurs in male gonads (testis). Surprisingly, the leading determinative factor in sexual differentiation of the gonads is the mesonephros, represented by the embryonic urinary system.     

Chum salmon (Oncorhynchus keta) stanniocalcin inhibitis in vitro intestinal calcium uptake in Atlantic cod (Gadus morhua)

Summary Chum salmon (Oncorhynchus keta) stanniocalcin was purified, partially identified and tested for bioactivity in an assay on the intestinal calcium uptake in a marine teleost (Gadus morhua). Basic ethanol extraction, ion exchange chromatography, gel filtration and reverse-phase high-performance liquid chromatography resulted in the isolation of a homogenous glycoprotein that appears as a 46-kDa product under non-reducing conditions and as a 23-kDa product under reducing conditions after sodium dodecylsulphate-polyacrylamide gel electrophoresis. The glycoprotein is likely to be a homodimer composed of two subunits of 23 kDa each. Further characterization indicates homology to Australian eel, sockeye salmon, coho salmon and rainbow trout stanniocalcin, and the glycoprotein is thus concluded to be stanniocalcin. Stanniocalcin-like immunoreactivity was demonstrated in the corpuscles of Stannius of the Atlantic cod, with a specific antiserum raised against purified chum salmon stanniocalcin. The physiological importance and the biological activity of chum salmon stanniocalcin was tested by evaluating its effect on intestinal calcium uptake by the Atlantic cod in vitro. The intestine was perfused, both vascularly and through the intestinal lumen, and the calcium mucosa-to-serosa flux was measured using ⁴⁵Ca²⁺ as a tracer. Stanniocalcin decreased the intestinal calcium uptake in a dose-related manner by 13.5% and 22.4% at doses of 2.2 and 10.9 nM stanniocalcin, respectively. The results establish the intestine as a target organ for stanniocalcin in marine teleosts.Abbreviations BIS balanced intestinal solution - CS corpuscles of Stannius - dpm disintegrations per minute - FW freshwater - J _in ^Ca influx of calcium across the intestinal mucosa - MW molecular weight - NRS normal rabbit serum - PBS phosphate buffered saline - PBST phosphate buffered saline containing 0.05% Tween-20 - PITC phenyl isothiocyanate - rp-HPLC reverse phase - SW seawater - STC phenyl isothiocyanate - rp-HPLC reverse phase - SW seawater - STC stanniocalcin - TFA Trifluoroacetic acid - Tris Tris(hydroxymethyl) aminomethan - V volume per fraction     

Fine structure of the corpuscles of stannius in the toadfish.

The micro-anatomy of the corpuscles of Stannius of the toadfish, Opsanus tau, an aglomerular marine teleost, has been studied by light and electron microscopy. The corpuscles are composed of extensively anastomosed cords of epithelial cells which maintain intimate contact with blood capillaries. Most of the epithelial cells contain acidophilic granules which also show a positive reaction with the periodic acid-Schiff technique and aldehyde fuchsin. On the basis of fine structural criteria, three cell types can be recognized. The granular cells contain abundant quantities of granular endoplasmic reticulum, ribosomes, Golgi apparatus with prosecretory granules, coated vesicles, polymorphic mitochondria with lamellar cristae, filaments, microtubules, a cilium, a variety of lysosome-like dense bodies, glycogen particles, lipid droplets, secretory granules and intranuclear lipid-like inclusions. One variety of agranular cell (type I) is characterized by the total absence of secretory granules, but it contains large amounts of granular endoplasmic reticulum and ribosomes, conspicuous profiles of Golgi apparatus, coated vesicles and sometimes an abundance of glycogen. Another variety of agranular cell (type II) has poorly developed cytoplasmic organelles. The perivascular space between the capillary and parenchyma contains connective tissue cells and abundant nerve fibers. The different types of epithelial cells observed in the corpuscles of Stannius of this fish may represent functional stages of the secretory cycle in a single cell type.     

Endocrine Control of Calcium Metabolism in Teleosts

It is evident that fishes regulate their serum calcium efficientlybut that endocrine systems involved may be different from thosein tetrapods. A functional parathyroid gland has not yet beendemonstrated in fishes. The majority of evidence indicates thatcalcitonin has little or no effect on fish calcium regulation.Instead, the corpuscles of Stannius and the pituitary glandare necessary for maintaining fish serum calcium levels. Inthe killifish, Fundulus heteroclitus, the removal of the corpusclesproduces hypercalcemia in sea water but not in artificial seawater deficient in calcium. Transplants of the corpuscles orthe administration of corpuscle homogenate corrects the increasein calcium. On the other hand, hypophysectomy elicits hypocalcemiaunder calcium deficient conditions but not in calcium rich seawater. Replacement therapy with pituitary homogenate or hypophysialtransplant prevents the fall in calcium. It is postulated thatthe hypocalcemic corpuscles of Stannius and the hypercalcemicpituitary gland enable the euryhaline killifish to regulateits serum calcium levels in high calcium sea water and low calciumfresh water, respectively.     

Evidence of hypocalcemic factor from corpuscles of Stannius of the teleost Heteropneustes fossilis (Bloch)

The administration of acid extract of corpuscles of Stannius has no effect on the plasma calcium level, in the normal fish, whereas the same dose shows typical hypocalcemic response in hypercalcemic fish, H. fossilis. It is concluded that acid extract of corpuscles of Stannius is effective only in hypercalcemic condition.     

Immunoreactivity of the corpuscles of Stannius of the garpike,Lepisosteus osseus,to antisera against salmon and trout stanniocalcins

Stanniocalcin-immunoreactive cells were localized in the corpuscles of Stannius of a holostean fish, the garpike (Lepisosteus osseus), using antisera against salmon and trout stanniocalcins and the peroxidase-antiperoxidase and protein A-gold immunohistochemical methods. The stanniocalcin-immunoreactive cells were periodic acid-Schiff-positive, and antibody staining was abolished if the antiserum was preabsorbed with corpuscle homogenate. Immunocytochemistry revealed two reactive cell types in the glandular parenchyma, and immunoreactivity was confined to the secretory granules. Staining of the granules was also abolished when the antisera were blocked with crude corpuscle homogenate. When corpuscle extracts from garpike were subjected to sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blot analysis, a single dense band was evident with a molecular weight of 68 kDa under non-reducing conditions, whereas three bands were observed (29, 31, and 34 kDa) under reducing conditions. Staining of all bands disappeared following preabsorption of the antiserum with salmon stanniocalcin, trout stanniocalcin, or garpike corpuscle extract. The results are compared with stanniocalcins from another extant holostean, the bowfin (Amia calva), and from more modern bony fishes, the teleosts.     

Corpuscles of Stannius and stanniocalcin-like immunoreactivity in the white sucker (Catostomus commersoni): evidence for a new cell-type

The distribution of stanniocalcin immunoreactivity was examined in the corpuscles of Stannius of the white sucker (Catostomus commersoni) by using a chum salmon stanniocalcin antiserum, Western blotting, and light and electron microscopy. The white sucker possesses at least two stanniocalcin-immunoreactive corpuscles in the most posterior portions of the kidneys. Immunocytochemistry and ultrastructure revealed two cell-types in the corpuscle parenchyma, only one of which was immunoreactive. The nonimmunoreactive cells contained dense-cored vesicles and long processes that extended between the immunoreactive cells and terminated at perivascular spaces. When corpuscle extracts were subjected to electrophoresis and Western blotting, three nonreduced stanniocalcin-like immunoreactive bands (approximately 56, 61, and 64 kDa) were observed. However, in the presence of a reductant, a diffuse band migrating in the range of 28 to 32 kDa was noted. The results of this study on the white sucker demonstrate the presence of a dimeric stanniocalcin-like molecule and present evidence of a previously uncharacterized cell-type in the corpuscles of Stannius.     

Morphological peculiarities of pronephros in Russian sturgeon, Acipenser gueldenstaedtii Brandt (order acipenseriformes, family acipenseridae)

The structure of the pronephros in Russian sturgeon larvae, Acipenser gueldenstaedtii Brandt, at different stages of early postembryonic development (from hatching till 14 days old), was studied with histological and electron microscopy methods. The formed pronephros is represented by a system of bilaterally located pronephric tubules and an external single glomus, which is not integrated directly into pronephric tubules and is located in closed pronephric chamber. The glomus is positioned below the dorsal aorta and is vascularized by its capillaries. The thin structure of the glomus has the same characteristic features that are typical of and needed for the functions of any filtering organ. By the time when larvae transfer fully to exogenous feeding, the pronephros undergoes significant degradation and it is replaced by the mesonephric kidney which develops during the period of function of the pronephros. The peculiarities of the pronephros in acipenserids are discussed comparatively with the same organ in teleosts and amphibians.     

Similar developmental patterns in immunolocalisation of stem cell factor and KIT in bovine meso- and metanephros

The mesonephros is often regarded as a simplified version of the terminal renal organ, the metanephros. Both renal organs result from an epithelio-mesenchymal interaction between the Wolffian duct and the nephrogenic ridge. It appears that the epithelio-mesenchymal interaction makes use of similar signal cascades for both renal organs and that key events required for the development of the metanephros occur at earlier stages. In murine metanephroi, the stem cell factor (SCF)/-KIT-signal transduction pathway has recently been shown to regulate ureteric bud branching and epithelial cell differentiation. We immunohistochemically defined the time-sequence of KIT and SCF presence in both renal organs using bovine embryos/foetuses with crown rump length (CRL) of 1.7–24 cm. In the mesonephroi, epithelial cells with strong KIT staining were scattered in distal tubules, and SCF was expressed in the epithelial wall of corpuscles and proximal tubules. KIT positivity occurred in the metanephroi of embryos prior to SCF; KIT was predominantly localised at the ureteric bud tips in the nephrogenic zone. In foetuses of 13 cm and more CRL, the SCF/KIT profile of developmentally advanced nephrons mirrored the situation in the mesonephros. Epithelial cells with strong KIT staining were scattered in the cortical areas of distal tubules, while SCF was expressed in the epithelial wall of corpuscles and proximal tubules. Our morphological findings agree with a potential role of KIT at the ureteric bud tips and demonstrate a similar expression of KIT and SCF along the areas of developmentally advanced mesonephric and metanephric nephrons.     

The relationship between the ionic composition of the environment and the secretory activity of the endocrine cell types of stannius corpuscles in the teleost Gasterosteus aculeatus

Summary The corpuscles of Stannius of threespined sticklebacks contain two glandular cell types of presumed endocrine nature. To elucidate the function of both cell types the secretory activity of the cells was studied in fully adapted seawater and freshwater fishes and in specimens transferred from sea water to fresh water or adapted to media of various ionic composition. The secretory activity was established, in tissue sections and freeze-etch replicas, by estimating the volume of the nuclei, the density of the nuclear pores, and the frequency of exocytotic phenomena.The type-1 cells, ultrastructurally comparable to the predominant or only cell type described in many other teleosts, are more active in sea water than in fresh water. The activity of the type-2 cells, whose ultrastructural appearance is known only for salmonids and eels, is higher in fresh water. Transfer of seawater fishes to fresh water results in reduction of type-1 cells and activation of type-2 cells. The factors responsible for these changes were analyzed by exposure of fishes to solutions of various salts in fresh water and to artificial sea water with a reduced content of one of its components. The high activity of type-1 cells in sea water proved to be related to the high calcium content of this medium. These cells probably produce a substance comparable to hypocalcin, the endocrine factor isolated from the Stannius corpuscles of some other teleost species. The high activity of type-2 cells in fresh water appeared to be connected with the low sodium and potassium levels of this medium. Type-2 cells possibly produce a hitherto unknown hormone involved in the control of sodium and/or potassium metabolism.The technical assistance of Miss C. Mein and Mr. J. Zagers is gratefully acknowledged