Figure 1.

Generation of Crhflox mouse and Crh null mouse (a). Schematic diagram of mouse Crh gene targeting. Wild-type (WT) Crh allele, targeting vector, Neo allele, flox allele, null allele are drawn. Broken lines indicate corresponding locations on each allele or the vector. The targeting vector has two artificial insertions, of which the upstream insertion contains one loxP sequence between exon1 (e1) and exon2 (e2), while the downstream insertion located downstream of exon2 contains the neomycin resistant gene (Neo) flanked by two frt sequences accompanied by an adjacent downstream loxP sequence. The location of two internal BamHI sites and one artificial BamHI site are indicated. Thymidine kinase (TK) is a negative selection marker. Characterization of Crhflox (Crhfl/fl) and CrhKO (Crhdl/dl) mice (b–q). (b–g) Crh-immuno-reactive neurons and fibers were observed in the paraventricular nucleus of hypothalamus (PVH) and central amygdala (CeA) in CrhWT (b, c) and Crhflox (d, e) but not in CrhKO mice (f, g) (scale bar, 100um); (h–k) Adrenal hypoplasia in CrhKO mice. Adrenals from adult male Crhflox (h, i) and CrhKO (j, k) were haematoxylin-eosin stained after paraformaldehyde fixation. CrhKO mice revealed thinner zona fasciculata. Left panel, low magnification (scale bar, 100um); right panel, high magnification (scale bar, 100um); (l–q) Confirmation of fetal lung dysplasia in CrhKO which was rescued by in utero corticosterone replacement. Crhflox fetus revealed normal lung development (l, m) while deletion of Crh cause hypercellular lungs with thick alveolar septae and a paucity of air spaces (n, o). The deficiency of lung development was rescued by corticosterone administration (30ug/ml in drinking water) to female pregnant CrhKO mice (p, q). Left panel, low magnification (scale bar, 100um); right panel, high magnification (scale bar, 100um);