Background and aims: Of the thirteen active carbonic anhydrases, CA IX and XII have been linked to carcinogenesis. It has been suggested that these membrane-bound CAs participate in cancer cell invasion. Since active cell migration is a characteristic feature of embryonic development, the aim of the study was to explore whether these isozymes are expressed in mouse embryos of different ages.

Methods: In situ hybridization was used to detect the expression of CA IX and XII mRNA. For this, radioactively labelled riboprobes were constructed. CA IX and XII protein expressions were studied immunohistochemically with a peroxidase-antiperoxidase method.

Results: The expression of CA IX and XII mRNA could not be revealed due to problems with the in situ hybridization method. Examination by immunohistochemistry showed that both CA IX and XII are present in several tissues of the developing mouse embryo during organogenesis. Staining for CA IX revealed a relatively wide distribution pattern, including the brain, pancreas and liver with moderate signals, and the kidney and stomach with weak signals. The expression pattern of CA XII was also relatively broad, although the intensity was weak in most tissues. The positive tissues included the brain, where the most prominent staining was seen in the choroid plexus, and the stomach, pancreas, liver and kidney.

Conclusions: Since both isozymes were present in some embryonic tissues whose adult counterparts do not express these particular proteins, one could hypothesize that CA IX and XII may have specific roles in the assembly of certain tissues.

Asiasanat: carbonic anhydrase IX, carbonic anhydrase XII, expression, embryonic, mouse, in situ hybridization, immunohistochemistry