*5.3.1 Qualitative analysis of exocrine and endocrine cell ultrastructure*

The pancreas is composed of exocrine and endocrine tissue and this functional specialization can readily be recognized microscopically (**Figure 2**).

#### **Figure 1.**

*Study design (A) timeline of the study. The part of the project shown in yellow is presented in this chapter. (B) Energy profile of control diet (CD) and western diet (WD).*

*Application of Transmission Electron Microscopy to Detect Changes in Pancreas Physiology DOI: http://dx.doi.org/10.5772/intechopen.104807*

#### **Figure 2.**

*Mice are fed with control diet (CD). (A) and (B) Semithin sections of the pancreas. (A) Exocrine part of the pancreas is composed of acinar cells (one cell marked by the yellow dotted line), organized in acini (one acinus marked by the green dotted line) and lobules (one lobule marked by the red dotted line). (B) Endocrine cells forming a Langerhans islet are seen as brighter stained cells (red dotted line). (C–F) Ultrathin sections of the pancreas. (C) Exocrine cells are easily recognized by their large size, typical shape, by abundant rough endoplasmic reticulum, and secretory granules. (D) The majority of secretory granules are found in the apical part of the cell. (E) and (F) endocrine cells can be distinguished by the fine structure and size of their secretory granules. In all endocrine cells, well-developed rough endoplasmic reticulum, Golgi apparatus, and numerous mitochondria are seen. AC, acinar cell; α, alpha cell; β, beta cell; δ, delta cell; D, duct; IL, islet of Langerhans; GA, Golgi apparatus; M, mitochondrion; N, nucleus; nu, nucleolus; RER, rough endoplasmic reticulum; SG, secretory granules. Scale bars: (A) and (B) 50 μm; (C) 2.5 μm; (D) 2 μm; (E) 5 μm; (F) 2.5 μm.*
