Material and Methods
Thyroid glands of 326 cadavers ranging in age from immediately after birth to 88 years of age were collected for this study from the district around Nagoya City which is situated in the Plain of Nohbi, one of the littoral plains in Japan. One half of the glands were removed bilaterally or unilaterally from cadavers after postmortem examination in the Departments of Pathology and Forensic Medicine, Nagoya University School of Medicine, and the other half in toto from students’ dissection material in the Department of Anatomy. Causes of death of the cadavers were mostly violence, accident and suicide or different diseases, as summarized in Table 1. Clinical and pathological records of each cadaver were reviewed as carefully as possible, especially in regard to history which could be related to thyroid diseases. All cadavers which indicated any evidence of abnormality of the thyroid gland were excluded from this study. Thyroid glands were fixed in 10% formalin solution or sometimes in Helly’s and Ciaccio’s fluids. Right (or left) lobes and those with the isthmus were transversely sliced into 5 pieces by safety razor blades. Further, 20 pyramidal lobes were sliced into two longitudinal pieces. The pieces were observed without any treatment at low magnifications by the binocular stereo dissection microscope to study the coarse histological appearance and at the same time to find other abnormal conditions. Materials examined histologically in detail consisted of a series of one or two pieces of the middle part of the lobe, most of which had the isthmus, and further the pieces of the pyramidal lobe. These pieces were embedded in celloidin or in paraffin, sectioned serially at 8 to 20 μ in thickness and stained with Hansen’s hematoxylin and eosin.
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