Insulin localizes to the ER of Sertoli cell nuclei. A: Akita homozygous mouse testes were fixed for electron microscopy and immunogold labeled for insulin (18-ng large gold particle)
and the Sertoli cell nuclear marker Sox9 (12-ng small gold particle). Insulin localizes to the ER surrounding the Sertoli
cell nuclei, labeled with Sox9. B: IgG negative control antibody. Bars represent 0.5 μm. um, μm.