Expression of the Xenopus laevis metallothionein gene during ontogeny.

Expression of the Xenopus laevis metallothionein (MT) gene was studied by in situ hybridization throughout development. MT mRNA was detected from the tailbud stage onwards. MT expression was observed in bucco-pharyngeal epithelium, pronephros and liver anlagen, aswell as in lens and periventricular areas of the encephalon. MT transcripts, in both larvae and adults, were detected in diverse regions of the central nervous system and in differentiating tissues implicated in detoxification processes: liver hepatocytes, small intestine epithelia and kidney tubules. These data are discussed in the context of MT functions and support a physiological role for MT in growth processes.