抄録
Omuro goiter is a congenital condition characterized by euthyroidism with a high familial incidence which was discovered in a fishing village in Kochi Prefecture, Japan. It was reported previously that the goiter may have been caused by a disturbance in the biosynthesis of thyroid hormone which was characterized by reduced formation of T4 and T3. This might suggest the presence of a defect of coupling of iodotyrosines to form iodothyronines. This paper reports morphological studies on 11 cases of Omuro goiter.
Characteristic features of the goiter seen by light microscopy were parenchymatous and adenomatous hyperplasia of the thyroid tissue associated with microfollicles containing a little colloid. Follicular cells were mostly cylindrical in shape.
Electron microscopy showed that the follicular lumen contained colloid of low density. Fine microvilli were found on the free luminal surface of the cylindrical follicular cells. The rough-surfaced endoplasmic reticulum was greatly dilated expanding into almost the entire cytoplasm. Mitochondria were scattered among the endoplasmic reticulum and some cells contained many fat droplets. Lysosomes varying in size and electron density were seen in the supranuclear region. The follicular cells contain a few secretory granules of low density but no colloid droplets. The Golgi apparatus was atrophic and inconspicuous. Transport of newly synthesized thyroglobulin from the rough endoplasmic reticulum into the Golgi apparatus may be partly inhibited by the weak development of Golgi apparatus, and this fact may bring about the extraordinary dilatation of cisternae of the rough-surfaced endoplasmic reticulum. Well developed endoplasmic reticulum indicates the active synthesis of thyroglobulin probably accelerated by the stimulation of TSH, whose secretion is increased.
