One explanation for the differences in glucose tolerance and insulin secretion seen in βVps13cKO mice may be an alteration in β-cell mass. To establish whether this was the case, we conducted immunohistochemical analyses on pancreatic sections from βVps13cKO and control mice fed RC and aged over 20 wk. Using antibodies against either insulin or glucagon, we observed no differences in %β- or α-cell surface normalized pancreatic surface (Fig. 9, A and B, females; C and D, males).