FIG. 5.

Immunohistochemical localization of Ddc expression during mouse heart development. Sites of positive Ddc immunoreactivity are marked by the brown signals. The hematoxylin counterstain appears as blue nuclear staining. (A) Parasagittal view of the e10.5 heart with positive Ddc staining in a small number of cardiomyocytes. Magnification, ×200. (B) Higher-magnification view of the e10.5 heart. Magnification, ×400. (C) Parasagittal view of the e14.5 heart, showing widespread Ddc staining in scattered trabecular cardiomyocytes. Magnification, ×200. (D) Higher-magnification view of the e14.5 heart. Magnification, ×400. (E) Parasagittal view of the newborn heart, showing persistent Ddc staining in trabecular cardiomyocytes. Magnification, ×10. (F) Higher-magnification view of the newborn heart. Magnification, ×400. (G) Low-magnification view of the 3-month heart showing an absence of Ddc staining. Magnification, ×10. (H) Higher-magnification view of the 3-month heart. Magnification, ×400. (I and J) Other sites of Ddc expression in e14.5 embryos: adrenal gland with Ddc staining in the secretory adrenomedullary cells (I) and Ddc expression in differentiating pancreatic acinar cells (J). Magnification (both panels), ×200. Control sections incubated with anti-rabbit immunoglobulin G secondary antibody alone did not produce signals (not shown).