ULTRASTRUCTURAL MORPHOGENESIS AND FUNCTIONAL-DIFFERENTIATION OF THE DOGFISH THYROID-FOLLICLE

  • 1 January 1979
    • journal article
    • research article
    • Vol. 68  (1) , 43-60
Abstract
From the 20 mm stage, in the cells of the dogfish thyroid, some Golgi vesicles get the ability to trap I. At subsequent stages, electron-dense intracytoplasmic cavities with microvilli are observed in the Golgi field; their membranes also trap I. These cavities increase in volume, draw toward the cellular periphery and export their contents in an intercellular space previously limited by tight junctions. The same events occur in several adjacent cells, which constitute the 1st follicular lumen. The last stage of follicular individualization is basement membrane formation. Arguments are given which support the hypothesis of the Golgi origin of intracytoplasmic cavities with microvilli. I organification just as thyroid hormone synthesis and secretion occurs at the 25 mm stage, when cells are not grouped in follicle. Cells containing intracytoplasmic cavities with microvilli are fully functional units.