Validity of the 21-OH/LacZ transgenic mouse as a model for studying adrenocortical cell lineage

Mosaic P-galactosidase reporter staining patterns in the adult adrenal cortex of 21-OH/ LacZ transgenic mice were compared to those observed in mouse chimeras and X-inactivation mosaics, which are known to have a lineage basis. This revealed similar patterns of blue and white radial stripes in all three experimental groups. Each blue stripe may contain one or more blue coherent clones of cells but this was taken into account by correcting the observed stripe numbers for the effects of different proportions of LacZ-positive (blue) and LacZ-negative (unstained) cells between adrenals. The corrected stripe numbers were similar in all three experimental groups, which supports the hypothesis that the stripes in the adrenals of 21-OH/LacZ transgenic mice are formed in a similar way to those in chimeras and X-inactivation mosaics (i.e., they have a lineage basis). This suggests that the 21-OH/LacZ transgenic mouse is likely to be a valid model for studying steroidogenic cell lineage in the adrenal cortex, thereby providing additional support for the centripetal migration hypothesis of adrenocortical cytogenesis.