GENETIC-REGULATION OF BORDER ZONE FORMATION IN FEMALE MASTOMYS (PRAOMYS COUCHA) ADRENAL-CORTEX

The unique border zone between the zona fasciculata and z. reticularis of the female adrenal cortex is formed in the wild-colored inbred mas tomys (Praomys coucha) strain, MWC, but never in the chamois-colored i nbred strain, MCC. This clear strain-specific trait was genetically an alyzed using F-1, F-2, and backcross progenies produced between MWC an d MCC. Reciprocal crosses gave no significant differences in the pheno typic ratio of F-1 or F-2 progeny. Border zone formation was detected in 0% of F-1 females, 25.8% of F-2 females, 0% of backcross females be tween F-1 and MCC, and 47.7% of backcross females between F-1 and MWC. From these results, it was concluded that border zone formation in th e female MWC adrenal is regulated by a single autosomal recessive gene and this gene was named bzf (border zone formation).