During spontaneous metamorphosis of bullfrog tadpoles, the gut weight/total weight and gut length/body length decreased by stage XVIII and reached maximum reductions of 80 and 85%, respectively, by stage XXII. When triiodothyronine was injected ip at stages X-XII, decreases in gut weight and length ratios were noted as early as 24-36 hr and prior to detectable tail regression. Maximum decreases in gut weight and length ratios of 65 and 69%, respectively, were achieved after 6 days at 25°C. Both endogenous and exogenous thyroid hormones stimulated a pronounced regression of the gut prior to detectable tail resorption. These data suggest the value of further in vivo and in vitro studies using the tadpole gut as a model for tissue regression.
ASJC Scopus subject areas
- Animal Science and Zoology