Morphology of OBs. (A) The shape of the primary cells nearly resembles that of a spindle and a polygon. (B) The primary cultures reach confluency by day 7 and exhibit dense clusters at day 10. (C) OB morphology after subculture. All subcultures reach confluency after 4 days to 7 days and form continuous cell multilayers. The latter cultures form isolated or interconnected and multilayered islands of cells widely dispersed on the flask surface. (D) The OB growth curve illustrates that the proliferative rate of the OB from patients with MBD are constitutively suppressed.