Effects of Parietalectomy and Sustained Temperature on Thyroid of Lizard, Sceloporus occidentalis.

Abstract

1. Parietalectomized lizards (Sceloporus occidentalis), free living in the field, presented evidence of above-normal thyroid activity in animals collected in winter and spring, but not in summer. 2. An annual cycle of thyroid activity is exhibited by both parietalectomized and sham-operated lizards. 3. Thyroid hypertrophy induced by 3 weeks of constant temperature (35°C) is mediated by the hypophysis.