Pituitary Function in the Thyroidectomized Rat

Contopoulos, A. N.; Simpson, Miriam E.; Koneff, Alexei A.

doi:10.1210/endo-63-5-642

Cited by 79 publications

(19 citation statements)

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“…Intracisternal granules similar to those observed in the MSH cell have also been observed within the endoplasmic reticulum cisternae of thyrotrophic hormone cells after thyroidectomy (31,32) In these cells conditions are similar to those in MSIt cells removed from hypothalamic control (4,33,34), as after thyroideetomy there is also a dramatic increase in the rate of hormone release (35). On the basis of a fine structural study of the thyroidectomy cell, Farquhar (32) has suggested that as a secondary feature of the increased secretory activity the removal of secretory product from the endoplasmic reticulum cisternae fails to keep pace with the production of it and, as a result, it accumulates and eventually prematurely condenses m the form of intracisternal granules.…”

Section: Discussionmentioning

confidence: 53%

The Biosynthesis, Intracellular Transport, and Packaging of Melanocyte-Stimulating Peptides in the Amphibian Pars Intermedia

Hopkins

1972

The Journal of Cell Biology

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Experiments in which glycine-3H has been introduced into excised neurointermediate lobes ofXenopus Iaevi$ incubated in a modified Krebs-Ringer bicarbonate medium have shown that ~-~ 50% of the incorporated radioactivity is present in small peptides which have an electrophoretic mobility characteristic of the melanocyte-stimulating (MSH) peptides shown to be elaborated within the tissue. Based on these results and the demonstration that a discrete ~-~ 7 min pulse of the label can be introduced into the tissue, electron microscope radioautography has been employed to follow the subcellular events concerned with the synthesis, intracellular transport, and packaging of the labeled secretory product. Together, these studies indicate that the newly synthesized material arises in peptide form, rather than as part of a larger prohormone molecule, on the ribosomes of the rough endoplasmic reticulum within the parenchymal cells of the intermediate portion of the lobe. A proportion is then incorporated into and remains for an extended period within the intracisternal granules which are a feature of the rough cndoplasmic reticulum within these cells in vitro Most (~ 60%) of the labeled secretory product, however, is transferred to the Golgi complex within 30 rain and, within a further 10 rain, becomes packaged into small (~ 200 m/l) electron-opaque secretory granules. It is probable that under the conditions employed these granules represent the final intracellular location of secretory product before it is released

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Section: Discussionmentioning

confidence: 53%

The Biosynthesis, Intracellular Transport, and Packaging of Melanocyte-Stimulating Peptides in the Amphibian Pars Intermedia

Hopkins

1972

The Journal of Cell Biology

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“…It was also reported that after thyroidectomy the pituitary GH content was lowered while the serum GH activity was elevated (Contopoulos et al, 1958;Solomon and Greep, 1959;Amerbury et al, 1965;Schooley et al, 1966). Ishikawa et al(1972) centrifuged pellets of the isolated acidophils less contaminated with the cells of other kind and classified acidophil granules into two patterns according to their diameter; the large ones approximately 350 m,u and the small ones, about 130 my.…”

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confidence: 99%

Fine Structure of Pituitary Acidophils in Thyroidectomized Rats with or without the Treatment with Thyroxine and Dexamethasone

Harumiya

1972

Endocrinol Japon

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SynopsisElectron microscopic study was made on rat anterior pituitaries in an attempt to clarify the causal mechanism of "loss of acidophils" which could be detected with the light microscope following thyroidectomy. In the advancing days after thyroidectomy, the acidophils (somatotrophs) were gradually deprived of their large granules whose diameter was about 350 mu. There was evidence in vivo for the first time that there were some acidophils containing only the small granules, about 130 mu in diameter, after the 7th postoperative day. This clearly showed the simultaneous existence of two different sizes of granules in the same acidophils. As time elapsed, the large granules dispersed from the acidophils. After the 30th day these acidophils began to adjust their shape into the polygonal cells. Eventually, the acidophils completely lacking granules of either size occassionally appeared on the 90th and 200th days. Thus thyroidectomy had a strong influence to release the large granules, whereas an influence to release the small ones was not remarkable. The replacement injection of thyroxine into the thyroidectomized rats efficaciously reproduced the large granules which were generally considered to be responsible for GH storage. The repeated administrations of dexamethasone to the thyroidectomized rats resulted in the increase in number of small granules that were thought by us to be the storage carriers of ACTH. On the other hand, this compound alleviated loss of large granules following thyroidectomy. The final fate of acidophils after thyro:c.ectomy was, however, still vague because of the equivocal distinguishment of these degranulated acidophils from the immature basophils. Thus, the "loss of acidophils" may not mean the intrinsic disappearance of the cells themselves, but represent a transient loss of the large dense granules in the remaining acidophils.

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“…histometrically calculated the number of thyrotrophs following thyroidectomy upon the preparations stained with PAS-iron hematoxylin and aldehyde thionine-PAS-luxol fastblue respectively, and pointed out that the increase in number of thyrotrophs waned during a period between the 10th and 60th days of thyroidectomy and their largest population represented an increase by 5% on the 40th day. The pituitary TSH content diminished during the early phase of thyroidectomy and the reduced value continued for as long as 20 or 42 days after the operation (Mess, 1958;Contopoulos et al, 1958;Salomon, 1964). Also Panda and Turner (1967) …”

Section: Methodsmentioning

confidence: 99%

Degranulated Acidophils as a Possible Original Source of “Thyroidectomy Cells” in the Rat Hypophysis

et al. 1973

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SynopsisThe original source of thyroidectomy cells (TX-cells) in rats was investigated electron microscopically. Thyrotrophs did not respond so definitely to thyroidectomy as gonadotrophs did to castration. In thyrotrophs, changes in terms of hyperplasia, hypertrophy and de-or hypergranulation were not manifested. There was no evidence that TX-cells belonged to hyperactive thyrotrophs. The course of transformation from the degranulated acidophils to TX-cells was clearly demonstrated in sequence in this study. Hypertrophy, deformation of the cell, expansion of cisternae, occurrence of intracisternal granules and enlargement of the Golgi-ring, these were manifestations of the developmental process of degranulated acidophils into TX-cells. The other process of transformation of acidophils into TX-cells seemed related to the gradual dilation of ER without discharging their large granules completely. During the chronic phase of thyroidectomy, the anterior pituitaries were filled with TX-cells and their precursors. High vesiculation could be considered as an intrinsic biological reaction which is commonly seen in most of hypophyseal cells during thyroxine deficiency. It was, therefore, suggested that degranulated or slightly granulated acidophils might be predominantly the original sources of TX-cells. Thus, the acidophil theory has been firmly established as to the genesis of TX-cells. We, at the same time, wanted to open up a possibility that some TX-cells might arise from immature basophils, but the valid evidence was not produced in this study. It was verified electron microscopically that the fully developed round TX-cells seemingly like signet-ring-typed castration cells were quite different from genuine castration cells, although both cells had the same staining properties and light microscopical characteristics. However, a number of immature gonadotrophs came into being during the chronic phase of thyroidectomy.

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Pituitary Function in the Thyroidectomized Rat

Cited by 79 publications

References 0 publications

The Biosynthesis, Intracellular Transport, and Packaging of Melanocyte-Stimulating Peptides in the Amphibian Pars Intermedia

The Biosynthesis, Intracellular Transport, and Packaging of Melanocyte-Stimulating Peptides in the Amphibian Pars Intermedia

Fine Structure of Pituitary Acidophils in Thyroidectomized Rats with or without the Treatment with Thyroxine and Dexamethasone

Degranulated Acidophils as a Possible Original Source of “Thyroidectomy Cells” in the Rat Hypophysis

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