GFP is expressed in transgenic and knock-in mouse embryos. (A) Structure of 7.0IS GFP and 3.1ISIGII GFP transgenic constructs. Top line represents the structure of the mouse GATA-2 gene. Black arrow and blue arrow indicate the transcription and translation initiation sites, respectively. The map of the murine GATA-2 gene, modified to express EGFP in knock-in mouse, is also shown. (B-C) TG-GFP expression profile of the 3.1ISIGII GFP transgenic mouse E10.5 embryo (line no. 685). Panel C shows a ventral view of the AGM region. Asterisk and m indicate the positions of dorsal aorta and mesonephros, respectively. (D) Immunostaining with anti-GFP antibody confirming the TG-GFP expression (brown) in the lining of the aortic wall and in the cells ventral to the dorsal aorta (red arrow) of an E11.5 embryo (line no. 685). (E) Outline of the planar orientation of E8.0 embryo.¹⁷  (F) Confocal microscopic image of the region corresponding to the red square in panel E of line no. 798 transgenic embryo. Broken line in panel F indicates the position of the dorsal aorta. (G) Sagittal image of E9.0 embryo (line no. 798). (H-I) KI-GFP expression in the E10.5 KI-heterozygous embryo. Panel I shows the AGM region of the KI heterozygous embryo. Asterisk and m indicate the position of the dorsal aorta and mesonephros, respectively. (J) Anti-GFP antibody staining of the transverse section of the aorta of E11.5 embryo. (K) KI-GFP fluorescence along the dorsal aorta of E8.0 KI-heterozygous embryo. (L) Immunostaining of E11.5 AGM region with FITC anti–GATA-2 antibody (left), and with control rat antibody (right). (M) Immunohistochemical staining with anti–GATA-2 antibody showing endogenous GATA-2 expression in the lining of the dorsal aorta and in neighboring mesenchymal cells of an E11.5 embryo. See “Materials and methods.” Original magnification for panels D, J, and M is × 100.