Origin of intracellular colloid droplets in the rat thyroid
NJ Nadler, SK Sarkar, CP Leblond - Endocrinology, 1962 - academic.oup.com
NJ Nadler, SK Sarkar, CP Leblond
Endocrinology, 1962•academic.oup.comAfter a single injection of thyroid-stimulating hormone (TSH) to rats, discrete droplets, which
stain like the colloid in the lumen, were located in one or more of 3 sites: 1) within streamers
of cytoplasm extending into the lumen from the apex of the follicular cells, 2) within the body
of the cells either toward the apex or 3) toward the base. In a first experiment, counts of
colloid droplets in these 3 locations after TSH injection indicated that they appear first in the
cell streamers, later in the apex, and finally in the base of the cells. In a second experiment …
stain like the colloid in the lumen, were located in one or more of 3 sites: 1) within streamers
of cytoplasm extending into the lumen from the apex of the follicular cells, 2) within the body
of the cells either toward the apex or 3) toward the base. In a first experiment, counts of
colloid droplets in these 3 locations after TSH injection indicated that they appear first in the
cell streamers, later in the apex, and finally in the base of the cells. In a second experiment …
After a single injection of thyroid- stimulating hormone (TSH) to rats, discrete droplets, which stain like the colloid in the lumen, were located in one or more of 3 sites: 1) within streamers of cytoplasm extending into the lumen from the apex of the follicular cells, 2) within the body of the cells either toward the apex or 3) toward the base. In a first experiment, counts of colloid droplets in these 3 locations after TSH injection indicated that they appear first in the cell streamers, later in the apex, and finally in the base of the cells.
In a second experiment, colloid droplets were produced again by TSH, but in animals given leucine-H3 either ½ hour before sacrifice (when radioautography showed labeling solely of follicular cells) or 5 ½ hours before sacrifice (when labeling predominated in the luminal colloid). Only in the latter case was there any significant labeling of the colloid droplets. The interpretation was that the droplets originate from the luminal colloid—a conclusion in keeping with the sequence of events observed in the first experiment.
It is suggested that colloid droplets are formed by streamers of cytoplasm extending from the apices of follicular cells into the lumen and pinocytosing small portions of luminal colloid which, soon afterward, pass into the body of cells. The pinocytosis and eventual disintegration of colloid in follicular cells might play a role in the proteolysis of thyroglobulin as a prelude to the secretion of thyroid hormone.
Oxford University Press