FIG. 8.

Whole-body deletion of Derlin-2 leads to perinatal lethality and cartilage defects. (A) One-day-old pups from a litter containing a Der2^−/− mouse. Note the milk spots (arrowheads) in control mice and the absence of a milk spot in the Der2^−/− mouse. (B) A litter containing Der2^−/− pups was delivered via caesarean section and not permitted to feed for 2 h. Serum glucose levels were measured. (C) Body weights of Der2^−/− mice and their littermate controls at various ages. Der2^−/− mice did not survive beyond 52 weeks. Der2^−/− male and female mice did not vary significantly in their weights. (D) Skeletal lengths (nose to base of tail) of adult Der2^−/− and age-matched littermate control mice were measured. (E) Skeletons of a 9-month-old Der2^−/− and wild-type control mice were harvested and stained with Alizarin red and Alcian blue. Note the bottom three pairs of ribs connect to a single sternebra in the Der2^−/− mouse, indicating fusion of the third and fourth sternebrae (arrow). Der2^−/− rib cartilage is punctuated with linear calcifications (open arrowheads). (F) Skeletons were harvested from embryonic day 18.5 Der2^−/− and wild-type embryos and stained with Alizarin red and Alcian blue. Note that the ossification center (arrow) between the third and fourth sternebrae is smaller in Der2^−/− mice. (G) Hematoxylin and eosin staining of rib cartilage from adult wild-type and Der2^−/− mice (×20 magnification). (H) Sections were prepared as described for panel G. Arrows indicate chondrocytes with eosinophilic cytoplasmic inclusions in adult Der2^−/− mice. WT, wild type.