Ultrastructure of the thyrotrophic cell in the pars distalis of the lizard (2023)

Cited by (14)

  • Effects of TRH on hormone release from pituitaries of the lizard, Anolis carolinensis

    1988, General and Comparative Endocrinology

    The ability of thyrotropin-releasing hormone (TRH) to stimulate thyrotropin (TSH) from pituitaries of adult male lizards, Anolis carolinensis, was tested in vivo and in vitro. TSH output by pituitaries in vitro was determined by bioassay of the incubation medium using in vitro T4 output by thyroids from the same lizards. Pituitaries incubated without TRH had no detectable TSH secretion during two consecutive (2 or 3 hr) periods of incubation. Incubation in 10 or 100 ng/ml TRH for 2 or 3 hr significantly augmented release of TSH bioactivity in a dose-dependent manner. Pituitaries taken from goitrogen (100 μg methimazole/day for 10 days)-treated lizards had elevated basal TSH secretion but did not respond to TRH. TRH injection in vivo (5 μg/hr for 10 hr) appeared to stimulate acute release of MSH activity as judged by darkening of skin color after each injection, and plasma T4 was significantly elevated at the end of treatment. These results provide additional evidence that the reptilian thyrotrope has functional TRH receptors and the TSH-stimulating activity of the tripeptide along with its effects on other pituitary cells was present at an early stage of reptilian evolution.

  • L'ultrastructure de différentes cellules de l'adénohypophyse du lézard saharien Uromastix acanthinurus Bell 1825 (Sauria agamidae)

    1982, General and Comparative Endocrinology

    Les caractéristiques ultrastructurales de différentes cellules de l'adénohypophyse du lézard saharien, Uromastix acanthinurus, ont été définies: les cellules protidiques LTH, situées dans la région rostrale de la pars distalis, ont des granulations denses aux électrons (de 190 à 430 nm), de plus grande taille que celles d'autres éléments protidiques localisés dans la région caudale, les cellules STH (grains de 130 à 300 nm). Les cellules polypeptidiques ACTH, situées dans la région rostrale, ont des grains (de 150 à 410 nm) moins denses que ceux des catégories précédentes. Les cellules glycoprotidiques gonadotropes, rencontrées dans tout le lobe distal, ont des granulations de densité et de taille variables (de 170 à 460 nm), des corps lipidiques, des globules à aspect de lysosomes, et fréquemment des amas de filaments. Aussi bien dans les lobes distal qu'intermédiaire, on rencontre des cellules étoilées. La pars intermedia possède une catégorie principale de cellules granulaires (grains de 120 à 400 nm). Ces différentes catégories cellulaires ont été comparées à celles de l'adénohypophyse d'autres Reptiles.

    The ultrastructural characteristics of different cells of adenohypophysis of Saharian lizard Uromastix acanthinurus have been defined. In the rostral pars distalis, LTH cells contain electron-dense granules (190–430 nm in diameter) larger than those of other “peptide-secreting” cells concentrated in the caudal zone, the STH cells (granules from 130 to 300 nm). In the rostral pars distalis, “polypeptide-secreting” cells: ACTH cells have granules from 150 to 410 nm in diameter, less electron-dense than those of the preceding elements. Gonadotropic cells are scattered throughout the pars distalis; they have granules of variable density and diameter (170–460 nm), lipidic bodies, lysosomelike globules, and often a concentration of filaments. Stellate cells have been seen in the distal and intermediate lobes. The pars intermedia has a predominant cell type with granules of 120 to 400 nm in diameter. The different categories of cells have been compared with those of adenohypophyses of other reptiles.

  • Caveolar systems and sarcoplasmic reticulum in coronary smooth muscle cells of the mouse

    1979, Journal of Ultrasructure Research

    Vascular smooth muscle cells in mouse heart contain prominent membrane systems (“sarcotubules”). One of these systems consists of vesicular structures whose unit membranes are continuous with the sarcolemma and which occur either as single caveolae, more complex tubules, or branched chains of fused caveolae. Such caveolar systems are both analogous to, and homologous with, the T or T-axial tubular systems of striated muscle cells. A second system of membranes, the sarcoplasmic reticulum (SR), comprises tubules and saccules that often come into close association with the sarcolemma but apparently are not open to the extracellular space. In addition to forming “couplings” with the sarcolemma, the SR often comes into close contact with mitochondria and caveolae. The ultrastructural complexity of these membrane systems in coronary vascular smooth muscle equals or surpasses that of smooth muscle cells in the large blood vessels that have been extensively studied by other investigators.

  • Description de l'hypophyse du lézard saharien Uromastix acanthinurus bell 1825 (Sauria agamidae): Localisation par immunofluorescence de quelques hormones hypophysaires

    1979, General and Comparative Endocrinology

    L'hypophyse du lézard saharien Uromastix acanthinurus est comparable à celle des autres Agamidae. Le lobe intermédiaire est très développé. Le lobe distal allongé s'avance sous l'éminence médiane; il comprend une région rostrale et une région caudale (les 23 du lobe). Grâce à la technique d'immunofluorescence indirecte, nous avons mis en évidence dans la région rostrale de la pars distalis des cellules “prolactin-like,” des cellules “ACTH-like” et des cellules gonadotropes. On retrouve ces dernières, dispersées et isolées, dans la région caudale, où l'on rencontre aussi des cellules “STH-like” et de nombreuses cellules dégranulées.

    The pituitary of the saharian lizard Uromastix acanthinurus looks like those of other Agamidae. The pars intermedia is well developed. The elongated pars distalis is situated under the median eminence; it includes the rostral and caudal regions (two-thirds of the lobe). In the rostral region, the cytoimmunofluorescence technique has enabled us to reveal LTH-like cells, ACTH-like cells, and gonadotropin-producing cells. The latter are also revealed scattered in the caudal region where we find STH-like cells and numerous degranulated cells, also.

  • Immunohistochemical detection, by light and electron microscopy, of pituitary hormones in cold-blooded vertebrates. II. Reptiles

    1976, General and Comparative Endocrinology

  • Observations on the fine structure of the pars intermedia in the lizard Anolis carolinensis

    1972, General and Comparative Endocrinology

    The fine structure of the pars intermedia in Anolis carolinensis has been examined, and correlations between variations in its cellulai morphology and changes in skin color have been established in this animal. Two types of secretory cells are present in the pars intermedia of Anolis, and are designated as “light” and “dark” cells on the basis of their relative electron opacities. Light cells are by far the predominant form. Granules in the light cells are basophilic, whereas those in the dark cells are acidophilic. Secretory granules in light cells originate in Golgi saccules as dense masses and later enlarge to become much less opaque. In some secretory cells of either category an acidophilic, electron-opaque material appears to accumulate within the rough endoplasmic reticulum and to reach a high degree of compaction without becoming bounded by a smooth membrane and without apparent association with the Golgi apparatus.

    In addition to secretory cells, the pars intermedia contains agranular stellate cells that send long cytoplasmic processes between the secretory cells for considerable distances.

    In animals conditioned to maintain dark brown coloration, the light secretory cells show evidence of increased secretion, but the dark cells show no appreciable response. In animals maintained for long periods in a green state, the light cells give indication of less secretory activity; however, some differences were noted between responses in the partes intermediae of animals kept green by confinement in darkness and those of animals made green by confinement on an illuminated light background.

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Recommended articles (6)

  • Research article

    Evolution of IFN-λ in tetrapod vertebrates and its functional characterization in green anole lizard (Anolis carolinensis)

    Developmental & Comparative Immunology, Volume 61, 2016, pp. 208-224

    IFN-λ (IFNL), i.e. type III IFN genes were found in a conserved gene locus in tetrapod vertebrates. But, a unique locus containing IFNL was found in avian. In turtle and crocodile, IFNL genes were distributed in these two separate loci. As revealed in phylogenetic trees, IFN-λs in these two different loci and other amniotes were grouped into two different clades. The conservation in gene presence and gene locus was also observed for the receptors of IFN-λ, IFN-λR1 and IL-10RB in tetrapods. It is further revealed that in North American green anole lizard Anolis carolinensis, a single IFNL gene was situated collinearly in the conserved locus as in other tetrapods, together with its receptors IFN-λR1 and IL-10RB also identified in this study. The IFN-λ and its receptors were expressed in all examined organs/tissues, and their expression was stimulated following the injection of polyI:polyC. The ISREs in promoter of IFN-λ in lizard were responsible to IRF3 as demonstrated using luciferase report system, and IFN-λ in lizard functioned through the receptors, IFN-λR1 and IL-10RB, as the up-regulation of ISGs was observed in ligand-receptor transfected, and also in recombinant IFN-λ stimulated, cell lines. Taken together, it is concluded that the mechanisms involved in type III IFN ligand-receptor system, and in its signalling pathway and its down-stream genes may be conserved in green anole lizard, and may even be so in tetrapods from xenopus to human.

  • Research article

    How do lizards determine dominance? Applying ranking algorithms to animal social behaviour

    Animal Behaviour, Volume 118, 2016, pp. 65-74

    Dominance relationships are a defining feature of the social organization of many animal species. Populations structured by absolute dominance usually maintain a generally linear hierarchy, while relative dominance occurs, for example, within territorial populations where an animal is likely to be dominant within its territory. Because relative dominance is dependent on social context, the traits associated with it are often unclear. Green anole lizards, Anolis carolinensis, are an ideal system in which to determine dominance-related traits, as anoles use territorial defence in most natural environments, but establish a dominance hierarchy at high densities such as those that occur in captivity. We hypothesized that anoles use similar morphological and behavioural traits to determine social status under both forms of social organization. To test this, we studied a natural population of anoles to determine the traits most predictive of male territory size and quality (as measured by the number of females overlapping a male's territory). While these measures of territory may be related, they measure different components of territorial success. We then used mathematical ranking algorithms to quantify dominance in a tournament of paired arena trials, and identified traits associated with rank. Our results showed that lizards with wider heads had higher social rank, while those with longer heads were more successful at territorial defence. We also found that, independently of morphology, lizards who behaved more aggressively ranked higher in dominance trials, although behaviour did not predict measures of territory. Together, our results indicate that different traits may determine absolute and relative dominance in the green anole.

  • Research article

    Identification and Characterization of a Class of MALAT1-like Genomic Loci

    Cell Reports, Volume 19, Issue 8, 2017, pp. 1723-1738

    The MALAT1 (Metastasis-Associated Lung Adenocarcinoma Transcript 1) gene encodes a noncoding RNA that is processed into a long nuclear retained transcript (MALAT1) and a small cytoplasmic tRNA-like transcript (mascRNA). Using an RNA sequence- and structure-based covariance model, we identified more than 130 genomic loci in vertebrate genomes containing the MALAT1 3′ end triple-helix structure and its immediate downstream tRNA-like structure, including 44 in the green lizard Anolis carolinensis. Structural and computational analyses revealed a co-occurrence of components of the 3′ end module. MALAT1-like genes in Anolis carolinensis are highly expressed in adult testis, thus we named them testis-abundant long noncoding RNAs (tancRNAs). MALAT1-like loci also produce multiple small RNA species, including PIWI-interacting RNAs (piRNAs), from the antisense strand. The 3′ ends of tancRNAs serve as potential targets for the PIWI-piRNA complex. Thus, we have identified an evolutionarily conserved class of long noncoding RNAs (lncRNAs) with similar structural constraints, post-transcriptional processing, and subcellular localization and a distinct function in spermatocytes.

  • Research article

    Morphology of the Pituitary Gland in Ferrets (Mustela putorius furo) with Hyperadrenocorticism

    Journal of Comparative Pathology, Volume 130, Issue 4, 2004, pp. 255-265

    Pituitary tumours are the cause of hyperadrenocorticism in a variety of species, but the role of the pituitary gland in hyperadrenocorticism in ferrets is not known. In this species, the disease is mediated by the action of excess gonadotrophins on the adrenal cortex and is characterized by an excessive secretion of sex steroids. In this study, the pituitary gland of four healthy control ferrets, intact or neutered, and 10 neutered ferrets with hyperadrenocorticism was examined histologically following immunohistochemical labelling for adrenocorticotrophic hormone, α-melanocyte-stimulating hormone, growth hormone, thyroid-stimulating hormone, luteinizing hormone, follicle-stimulating hormone, and prolactin. Immunohistochemistry revealed that somatotrophs, thyrotrophs and lactotrophs were the most abundant cell types of the pars distalis of the pituitary gland in the healthy ferrets. The distribution of corticotrophs was similar to that in the dog and man. In ferrets, as in dogs, the melanotrophic cell was almost the only cell type of the pars intermedia. Gonadotrophs were found in the pars distalis of neutered, but not intact ferrets. All the ferrets with hyperadrenocorticism had unilateral or bilateral alterations of the adrenal gland. In addition, in the pituitary gland of two of these ferrets a tumour was detected. These tumours were not immunolabelled by antibodies against any of the pituitary hormones, and had characteristics of the clinically non-functional gonadotroph tumours seen in man. In some of the other ferrets low pituitary immunoreactivity for gonadotrophic hormones was detected, which may have been due to the feedback of autonomous steroid secretion by the neoplastic transformation of the adrenal cortex. It is concluded that initially high concentrations of gonadotrophins resulting from castration may initiate hyperactivity of the adrenal cortex. The low incidence of pituitary tumours and the low density of gonadotrophin-positive cells in non-affected pituitary tissue in this study suggest that persistent hyperadrenocorticism is not dependent on persistent gonadotrophic stimulation.

  • Research article

    Pituitary cysts and concretions in the gasterosteidae (teleostei)

    Journal of Comparative Pathology, Volume 97, Issue 2, 1987, pp. 149-157

    Pituitary cysts in the nine-spined stickleback, Pungitius pungitius, were found in the prolactin zone of the rostral pars distalis in 22 per cent of fish caught in May from freshwater, field-drainage ditches near Cardiff, Wales. They were not associated solely with some special environmental or hereditary factor in the Welsh population, for they were also present in 6 per cent of fish caught at a similar time of year in a freshwater lake at Manitoba, Canada. Although the pituitaries of other sticklebacks (Culaea inconstans, Apeltes quadracus and Gasterosteus wheatlandi) are similar to that of P. pungitius, they did not develop large cysts. There were no cysts at all in A. quadracus, and none > 50 μm in diameter in C. inconstans and G. wheatlandi. A minority of P. pungitius (< 1 per cent) develop concretions either within the pituitary (“intraglandular”) or in the surrounding capsule (“capsular”). Most of the concretions are filled with a strongly staining and laminated colloid. They are present in males and females, adults and juveniles, in fish killed soon after capture and in animals adapted to laboratory conditions. As far as we are aware, this is the first record of such structures in lower vertebrates.

  • Research article

    The pituitary gland of the coelacanth Latimeria chalumnae Smith

    General and Comparative Endocrinology, Volume 25, Issue 2, 1975, pp. 126-146

    Pituitary structure in the coelacanth Latimeria, the surviving member of the Crossopterygii, demonstrates features both shared and unique amongst the bony fishes.

    The neurohypophysis contains three areas of specialized neural contact. The anterior neurohypophysis comprises both a neurohemal organ—a median eminence—and an area of more direct, interdigitate contact with the pars distalis reminiscent of Amia. The predominant axon type of the median eminence contains a small monaminergic-type, dense-cored vesicle of 950 Å diameter. A neurointermediate lobe complex consists of branching tubular processes of the posterior neurohypophysis and follicles of the pars intermedia. The former contain peptidergic-type axons with large dense-cored vesicles of 1960 Å diameter which stain strongly as elementary neurosecretory granules (Knowles Type A). The saccus vasculosus is incompletely separated from the peptidergic posterior neurohypophysis.

    The tripartite pars distalis shows a more marked tendency toward compartmentalization relative to the lower Actinopterygii and the Dipnoi. Two major divisions of the pars distalis are evident on the basis of vascularization. The more orthodox proximal division is closely associated with the neurointermediate lobe and the portal vessels which appear to represent the major blood supply to this area. It comprises a purely acidophilic dorsal lobe (orangeophils and erythrosinophils), and a posterior lobe of mixed-cell type (orangeophils and basophils) which has a limited area of direct interdigitate neurohypophysial contact. The elongate extension of the pituitary so peculiar to the coelacanth comprises the rostral division which is connected only by a tubular hypophysial cavity to the remainder of the distalis. This virtually separated lobe has a substantial direct arterial supply derived from the internal carotids and contains relatively few chromophilic cells of basophil type in this immature female.

    The organization of the neurohypophysis in Latimeria is similar to that of other jawed fishes, particularly some relic actinopterygians. In contrast, the tripartite division of the pars distalis, the histologically separated rostral division with its direct arterial supply, basophil cell type, and close association with the carotid anastomosis, are unique features among the Osteichthyes, but are strongly reminiscent of the elasmobranch ventral lobe. Pituitary organization in Latimeria contrasts markedly with that of the lungfishes. The significance of this disparity in terms of the relationship of the two Orders of the Sarcopterygii (Romer) to each other, and of the unique features of the coelacanth in terms of its position as a sister group to the Rhipidistia, is discussed.

Copyright © 1971 Published by Elsevier Inc.

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