Figure 5

Very small embryonic-like stem cells in hematoxylin and eosin-stained smears of cell suspension obtained from normal pancreas. Very small embryonic-like stem cells in hematoxylin and eosin-stained smears of cell suspension obtained from normal pancreas at (A) 10×, (B) 20× and (C) 40× to give an idea of their very small size (arrow), because of which they have eluded researchers to date. Note that these cells have a distinct spherical shape, dark-stained nucleus, high nucleocytoplasmic ratio and minimal cytoplasm. Compared with the stem cells, somatic cells are bigger in size, have abundant cytoplasm and have relatively pale stained nuclei. Two distinct sizes of stem cells can be appreciated at higher magnification (C). The bigger stem cells undergo symmetrical cell division (SD), whereas very rarely we see a very small embryonic-like stem cell (VSEL) giving rise to a bigger stem cell by asymmetric cell division (AD). AD needs to be further characterized. Scale bar represents 20 μm. Flow cytometry analysis shows the presence of 2 to 5 μm VSELs that are LIN^–/CD45^–/SCA-1⁺ and comprise 0.6 ± 0.06% of pancreatic cells. APC, allophycocyanin; FITC, fluorescein isothiocyanate; FSC, forward scatter; PE, phycoerythrin; SSC, side scatter.