THE UPTAKE OF P32 AND HISTOLOGICAL CHANGES IN THE THYROID OF YOUNG CHICKS AFTER REPEATED STIMULATION WITH THYROTROPHIC HORMONE

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Abstract
The effect of repeated stimulation with thyroid stimulating hormone (TSH) on the uptake of p32, the mean acinar cell height, the percentage of epithelium and the weight of the thyroid was studied in day-old chicks. The birds were given 0.5 Junkmann-Schoeller units of TSH every 24 hours. The p32 uptake reaction almost subsided within 24 hours of each injection, and could be reactivated, especially if the radioactivity was expressed as counts per minute per mg thyroid tissue. Histological changes, however, were cumulative, giving rise to curves of the staircase type. Thus, a fundamental difference between the p32 uptake reaction and the histological reactions exist, the former not being dependent on the latter.