Figure 3.

Defective ECM in Sumf1^−/− growth plate. (A) Chondrocyte number in the growth plate proliferative zone. Values are the mean ± SD. Student’s test (*) P < 0.05. (B) Toluidin blue staining of chondrocostal cartilage of newborn Sumf1^−/− and wild-type littermates. Note the presence of cytoplasmatic vacuolization in Sumf1^−/− chondrocytes. (C) EM analysis of E14.5 Sumf1^−/− and wild-type chondrocytes showing no evidence of lysosomal vacuolization in Sumf1^−/− embryos. (D,E) Cytoplasmatic vacuoles in E16.5 (D) and newborn (E) Sumf1^−/− chondrocytes filled with amorphous material (GAGs) and partially degraded collagen fiber (E, inset). (F) Sumf1^−/− osteoblasts are less affected than chondrocytes by lysosomal vacuolization. (G) ECM proteoglycan produced by Sumf1^−/− and wild-type primary chondrocytes labeled with ³H-glucosamine and Na³⁵SO₄. ECM amount was estimated by ³H and ³⁵S incorporation and normalized for cells number. (H) Decreased alcian blue staining in P7 Sumf1^−/− compared with wild-type growth plate.