The release of follicular colloid from the thyroid of Necturus maculosus following heteroplastic anterior‐pituitary implants

Grant, Madeleine P.

doi:10.1002/ar.1090460302

Cited by 44 publications

(6 citation statements)

References 5 publications

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“…Earlier work that found that Necturus could not be induced to metamorphose by exogenous TH led to the hypothesis that the TRs in this species are not expressed or may not be functional. Given that Necturus has both a functional thyroid and functional TRs, detectable plasma TH (Charipper 1929; Grant 1930; Harris 1956; Rosenkilde and Ussing 1996), and TH‐dependent gene regulation, the question of the mechanisms that result in the obligate pedomorphic life‐history mode must be re‐addressed. As we found that TH induces gene expression in Necturus tissues, it is possible that the hormone causes some biochemical changes that are not evident at the level of organ morphology (e.g., the partial larval to adult fast isomyosin transition; Fox and Durand 1990).…”

Section: Discussionmentioning

confidence: 99%

Pedomorphosis revisited: thyroid hormone receptors are functional in Necturus maculosus

Safi

Vlaeminck-Guillem

Duffraisse

et al. 2006

Evolution and Development

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Heterochrony, a difference in developmental timing, is a central concept in modern evolutionary biology. An example is pedomorphosis, retention of juvenile characteristics in sexually mature adults, a phenomenon largely represented in salamanders. The mudpuppy (Necturus maculosus) is an obligate pedomorphic amphibian, never undergoing metamorphosis. Thyroid hormone induces tissue transformation in metamorphosing species and this action is mediated by nuclear thyroid hormone (TH) receptors (TRs). The absence of metamorphosis in Necturus has been attributed to a resistance to TH action as treatment with exogenous TH fails to induce transformation. The failure to metamorphose could be due to the lack of TR expression in target tissues, or to a loss of TR function. Toward understanding the molecular basis for the failure of Necturus tissues to respond to TH, and the ultimate cause for the expression of the obligate pedomorphic life history, we characterized the structure, function, and expression of TR genes in Necturus. Strikingly, we found that Necturus TRalpha and TRbeta genes encode fully functional TR proteins. These TRs bind both DNA and TH and can transactivate target genes in response to TH. Both TRalpha and TRbeta are expressed in various tissues. TH treatment in vivo induced expression in the gill of some but not all genes known to be activated by TH in anuran larvae, caused whole organism metabolic effects, but induced no external morphological changes in adults or larvae. Thus, Necturus possesses fully functional TRs and its tissues are not generally resistant to the actions of TH. Rather, the absence of metamorphosis may be due to the loss of TH-dependent control of key genes required for tissue transformation.

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Section: Discussionmentioning

confidence: 99%

Pedomorphosis revisited: thyroid hormone receptors are functional in Necturus maculosus

Safi

Vlaeminck-Guillem

Duffraisse

et al. 2006

Evolution and Development

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“…Droplets of a material which stains like thyroid colloid occur in the cytoplasm of epithelial cells of the thyroid gland (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). There are two hypotheses about the origin of these droplets.…”

Section: Introductionmentioning

confidence: 99%

“…Some investigators have suggested that the droplets may be freshly synthesized colloid made in the cell prior to secretion into the lumen of the follicle (4,5,11). Others have suggested that the droplets may contain colloid derived from the lumen of the follicle (1)(2)(3)(8)(9)(10). Using the classical methods of histology it did not seem possible to decide whether one or both of these hypotheses are correct.…”

Section: Introductionmentioning

confidence: 99%

Localization of Esterase and Acid Phosphatase in Granules and Colloid Droplets in Rat Thyroid Epithelium

Wollman

Spicer

Burstone

1964

The Journal of Cell Biology

137

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Droplets which stain like colloid occur in the cytoplasm of the thyroid follicular epithelium of the rat following stimulation of the gland by thyroid-stimulating hormone (TSH). The occurrence of droplets was remarkably reduced when the lumen became depleted of colloid. Acid phosphatase and esterase were localized in the thyroid droplets and, in addition, in granules largely around the nucleus. Stimulation by TSH resulted in an increase in the number of droplets containing enzyme. Twenty-four hours after hypophysectomy, enzyme-associated granules were localized at the basal end of the cell and droplets were absent. Intravenous injection of TSH resulted in formation of droplets at the apical end of the cell and migration of enzyme-associated granules toward the apical end of the cell. The droplets were first observed approximately 10 minutes after TSH administration and at this time did not appear to contain enzyme. Within 15 minutes many droplets contained enzyme. The granules were largely localized near the nucleus on its apical side 30 minutes after a dose of 25 milliunits of TSH, but were less well localized following one-tenth this dose. These results indicate that the epithelial cell of the thyroid gland contains preformed hydrolytic enzymes associated with granules (lysosomes). When the gland is stimulated by TSH, droplets are formed from colloid derived from the lumen (phagosomes), and hydrolytic enzymes are transferred from granules to the droplets. The droplets may be intracellular organelles for hydrolysis of colloid and liberation of thyroxine prior to the release of thyroxine into the blood.

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“…Although the volume of this transplant was many times larger than that of the tadpole's own hypophysis, mere quantity of secretion was unable to cause any more development than occurred in those animals into which no hypophyseal tissue was transplanted. Grant (1930Grant ( , 1931 stimulated the thyroid glands of larval salamanders by making intraperitoneal transplants daily of the pars anterior of the hypophysis of several species of frogs, striking effects being visible after four implants, while seven daily implants caused the complete disappearance of the colloid. In nearly all cases the tissues were healthy and showed every evidence of continued activity.…”

Section: -3mentioning

confidence: 76%

The Endocrine Control of Amphibian Metamorphosis

Allen

1938

Biological Reviews

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IN discussing the more recent experimental work upon the endocrine glands in their relation to amphibian metamorphosis, we cannot leave wholly out of account the earlier work that forms a basis for it; but the great volume of investigation in this field necessitates a limitation in an article of this character, more justified because of the fact that the writer published a survey article of this type in 1929 (Allen, 1929).For this reason the details of our study will concern chiefly such papers as appeared since that date, yet we must develop the basic principles of these earlier studies extending back to the year 1912 in order to lay our foundations.The pioneer workof Gudernatsch (1912), in which he demonstrated the fact that thyroid gland material fed to amphibians accelerates metamorphosis, was followed by studies by Allen (1916) and Hoskins, E. R. & M. M. (rgq), in which the con-

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The release of follicular colloid from the thyroid of Necturus maculosus following heteroplastic anterior‐pituitary implants

Cited by 44 publications

References 5 publications

Pedomorphosis revisited: thyroid hormone receptors are functional in Necturus maculosus

Pedomorphosis revisited: thyroid hormone receptors are functional in Necturus maculosus

Localization of Esterase and Acid Phosphatase in Granules and Colloid Droplets in Rat Thyroid Epithelium

The Endocrine Control of Amphibian Metamorphosis

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