Brain-engrafted thyroid tissue was found to be histologically and functionally similar to that of a normal in situ thyroid. The graft always contained a rich plexus of peri- and interfollicular vessels which anastomosed quite freely with the vascular bed of surrounding neural structures. Radioautographs and chromatographic analysis of graft tissue demonstrated the uptake of 131 I and the active incorporation of iodide into thyroid hormone and its precursors (T 4 , MIT, DIT). Electrophoretic examination of serum from thyroidectomized-implanted animals established the presence of thyroxine in peripheral blood and its association with the normal thyroxine-binding serum albumin components. These various lines of evidence suggest that the venous effluent of thyroid grafts provides adjacent brain areas with a higher than normal thyroid hormone titer. The results are discussed with reference to the applications and the limitations of this technique in neuroendocrine studies.
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Yasumura et al. (1964) studied this question.