Collagen XXVII Function in Growth Plate Figure 2. Col27G1516C mice have no gross phenotype. A. Growth curves for the offspring of heterozygous crosses. B. Skeletal preps of new born mice revealed a fusion of the 4th and 5th sternebrae (arrow and see inset) in mice homozygous for the mutation when compared with wild type littermates but no other differences. Scale bar = 5 mm C. X-ray analysis of 9 week old mice revealed no obvious phenotype of the skeleton in mutant mice. Scale bar = 10 mm. Wild type (WT/WT), Heterozygous (WT/MG/C), Homozygous (MG/C/MG/C). doi:10.1371/journal.pone.0029422.g002 was not a secondary consequence of the cartilage defect. However, MDskel/MDskel mice were strikingly dwarfed (Fig. 7) with affected mice often being only half the body weight of littermates and exhibiting a short snout and slightly domed skull (Fig. 7). X-rays revealed no overt skeletal patterning defects in the MDskel/MDskel mice but all of the long bones were shorter than those in the littermate control (Fig. 7). MDskel/MDskel mice also exhibited slight distortion of the thoracic cage, a mild thoracic kyphosis and a distortion of the pelvis (Fig. 7). MDskel/MDskel males were fertile but the fertility of females was not tested due to their small body size. Growth plate chondrocytes and their pericellular matrix are disrupted in MDskel/MDskel mice The growth plates of perinatal MDskel/MDskel mice were severely disrupted compared to littermate controls but the proliferative chondrocytes displayed some signs of flattening and organising into vertical columns (Fig. S3). At 3 weeks, the secondary centre of ossification in tibias and femurs of MDskel/ MDskel mice was indistinguishable from that of controls (data not shown). The proliferative zone chondrocytes in the 3 week old MDskel/MDskel mouse growth plates were adopting a flattened appearance and attempting to organise into vertical columns although the architecture remained disrupted in comparison with controls (Fig. 8A–B). In some instances, flattened proliferative chondrocytes were orientated at right angles to their normal plane and located between the vertical stacks of cells in the MDskel/MDskel growth plates (Fig. 8B). In these 3 week old mice, the level of immunostaining for collagen XXVII appeared equivalent in the control and MDskel/MDskel growth plates. However, collagen XXVII staining extended right up to the cells in the proliferative zone of MDskel/MDskel growth plates and these lacked the translucent stain-free pericellular matrix of the PLoS ONE | www.plosone.org 4 December 2011 | Volume 6 | Issue 12 | e29422