Number of secretory vesicles in growth hormone cells of the pituitary remains unchanged after secretion.
Immunogold-labeled transmission electron microscopy (TEM) was used to determine the total number of secretory vesicles in resting and in growth hormone (GH)-stimulated porcine pituitary cells. We identified three categories of vesicles: filled, empty, and partly empty. Resting GH cells contained more than twice as many filled vesicles than did the stimulated ones. Stimulated cells, however, contained nearly twice as many empty vesicles and 2.5 times more partly empty vesicles than did resting cells. Secretory vesicles in GH cells further revealed the localization of GH only in electron-dense vesicles in both resting and stimulated cells. The total number of secretory vesicles did not change after secretion. These results are consistent with a mechanism that, after stimulation of secretion, vesicles transiently dock and fuse at the fusion pore to release vesicular contents.
Lee
Jin-Sook
JS
Iowa State University, 2356 Kildee Hall, Ames, IA 50011-3150, USA.
Mayes
Mary S
MS
Stromer
Marvin H
MH
Scanes
Colin G
CG
Jeftinija
Srdija
S
Anderson
Lloyd L
LL
D000818:Animals; D005260:Female; D013006:Growth Hormone / Q000032:analysis / Q000378:metabolism*; D008297:Male; D016253:Microscopy, Immunoelectron; D010902:Pituitary Gland / Q000378:metabolism* / Q000648:ultrastructure; D022142:Secretory Vesicles / Q000648:ultrastructure*; D013552:Swine
D013006:Growth Hormone