Changes in Fine Structure and Acid Phosphatase Localization in Rat Thyroid Cells Following Thyrotropin Administration

Shortly after the administration of 1/40 unit thyrotropin to rats, 24 hours post-hypophysectomy, the following sequence of changes has been observed within thyroid follicular epithelial cells: (1) the appearance of apical cell surface activity consisting of pseudopods projecting into the follicular...

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Bibliographic Details
Published in:The Journal of cell biology 1965-06, Vol.25 (3), p.593-618
Main Authors: Wetzel, Bruce K., Spicer, Samuel S., Wollman, Seymour H.
Format: Article
Language:English
Subjects:
Acid Phosphatase - metabolism
Animals
Cell membranes
Cells
Colloids
Cytoplasm
Epithelial cells
Histocytochemistry
Hypophysectomy
In Vitro Techniques
Microscopy, Electron
Organelles
Phosphatases
Rats
Reaction products
Thyroid gland
Thyroid Gland - cytology
Thyroid Gland - drug effects
Thyroid Gland - enzymology
Thyrotropin - pharmacology
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Summary:Shortly after the administration of 1/40 unit thyrotropin to rats, 24 hours post-hypophysectomy, the following sequence of changes has been observed within thyroid follicular epithelial cells: (1) the appearance of apical cell surface activity consisting of pseudopods projecting into the follicular lumen; (2) apparent phagocytic engulfment of colloid droplets lacking indications of acid phosphatase activity; (3) close association and probable fusion of newly formed colloid droplets and dense granules, the latter cytochemically positive for acid phosphatase activity; (4) the appearance of presumptive acid phosphatase activity within colloid droplets; and, (5) further colloid droplet changes, viz., basipetal migration and decrease in size, accompanied by an increase in density and in demonstrable acid phosphatase activity. These changes appeared to represent the resorption and degradation of follicular colloid. Comparable results were obtained using intact and more heavily stimulated animals. Colloid biosynthesis was tentatively visualized in these cells as a separate mechanism involving small vesicles prominent in the Golgi region and beneath the apical plasma membrane of some, but not all, thyroid follicular cells in each specimen.
ISSN:0021-9525
1540-8140
DOI:10.1083/jcb.25.3.593