Observations on the fine particulate components in certain membrane-bound bodies of the rat thyroid cell
Dempsey and Peterson (1) and lately Ekholm and Sjöstrand (2) have given good preliminary accounts of the electron microscopy of the thyroid cell. However, apart from its readily identifiable cytoplasmic components this cell contains two somewhat ambiguous inclusion bodies. The first of these bodies in the rat thyroid is usually rounded membrane-bound and has a size range of 0.5 to 3.0 μ. Such inclusions contain a moderately dense material of comparable appearance to vesicular colloid (1) and it is noteworthy that the so-called “colloid” bodies observed by the light microscope have a comparable size range: in a current series on the rat thyroid, intracellular colloid bodies, staining positively with the periodic acid Schiff reagent, measured from 1/2 to 3 μ in diameter. Work, as yet unpublished, on the normal, activated and inactive thyroid (Lever, in preparation) supports the assertion (1) that these 0.5 to 3.0 μ-sized bodies seen in electron micrographs of the rat thyroid are in fact the intracellular colloid bodies and that they likely originate from the endoplasmic reticulum. Space does not permit their illustration in this paper and reference should be made to the figures in earlier works (1 and 2).
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