The conditional inactivation of <i>Arx</i> in glucagon-producing cells results in islet hypertrophy accompanied by islet neogenesis.

(A–I) Representative photographs of insulin immunohistochemical analyses performed on pancreata of 3–9 month-old Glu-ArxKO (D–F) and on age-/sex-matched controls (A–C)). Note the dramatic augmentation in islet size and the substantial increase in islet numbers in mutant animals. Similar alterations were also noted in IndGlu-ArxKO animals treated with Dox for 3 (G) and 10 (H–I) months. (Each photograph is representative of at least three independent animals). (J–K) These results were confirmed by the means of optical projection tomography whereby 5 month-old WT controls (J) and age-matched Glu-ArxKO animals (K) were assayed for insulin expression (also see Movie S1). Quantification of insulin+ cell volume revealed a significant 2.71-fold increase in Glu-ArxKO pancreata compared to controls.