part of ends during starts during death pelvic girdle endochondral bone ischium XAO:0004497 eriksegerdell 2013-04-10T19:03:50Z xenopus_anatomy Any of the posterior and smaller bones of the pelvic girdle. The ischia appear at NF stage 53, grow toward each other at NF stage 55, fusing and beginning to ossify by NF stage 58/59. ischia NF stage 54