Figure 7

Nkx6.1 expression is differentially dependent on Nkx2.2. (A-D) Nkx6.1 is broadly expressed in the pancreatic epithelium of wild type, Arx^-, Nkx2.2^-/- and Nkx2.2^-/-Arx^- mice at embryonic day 15.5. (E, F) In wild type and Arx-mutants, Nkx6.1 expression is maintained and detectable at P0. (G, H) However, in the absence of Nkx2.2 or Nkx2.2/Arx, a steady decrease in Nkx6.1⁺ cell numbers is detected from E15.5 on so that Nkx6.1⁺ cells are not detectable in pancreata of newborns. No co-expression of Nkx6.1 and ghrelin is detectable in wild type or mutant tissues at the investigated developmental time-points (original magnification 400×). (I-L) Nkx6.1⁺Sox9⁺ ductal/endocrine progenitors are present in all four genotypes at E15.5. In wild type and Arx-mutants Nkx6.1⁺Sox9^- cells are detected in comparable numbers. (K, L) However, in the absence of Nkx2.2 or Nkx2.2 and Arx no such cells are detectable. Pictures in I-L were taken using confocal microscopy. (M) Quantification of Nkx6.1⁺Sox9^- cell numbers in E15.5 pancreata of wild type, Arx^-, Nkx2.2^-/- and Nkx2.2^-/-Arx^- mice (n = 3 pancreas per genotype). Single-factor ANOVA coupled to Newman-Keuls test was applied and p-values < 0,05 were assessed as statistically significant compared to wild type. Statistical significance is achieved with the assumption of a normal distribution. Error bars represent SEM.