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Figure 8: Insulin secretion assay and ultrastructural studies on primary islet cell cultures. (a) Bright field images of primary islet cultures isolated from Mutant, Lean, and Control at 1, 6, and 12 months. Insights show the DTZ stained islets (magnification of 100x). (b) shows the ultrastructural studies of 12-month Mutant phenotypes by scanning (SEM) and (c) transmission electron microscopy (TEM). As shown in the figures Mutants showed less integrity with a ruptured outer collagenous layer (black arrows) and perforations (white arrow heads) (SEM), degranulation of insulin crystals, large less electron dense secretory granules (arrow head), and vacuolation (v) (TEM) compared to their Lean and Control. Insulin secretion measured from 250 islets: (d) basal (5.5 mmol/L glucose), (e) stimulated (16.5 mmol/L glucose), and (f) basal to stimulated insulin secretion, shows impaired insulin secretion with challenge (16.5 mmol/L glucose) from Mutants with age as compared to their Leans and Controls. However, Mutants showed higher basal insulin levels with age.