To provide the first look at the bony histologic features of fetuses with the exstrophy complex, specifically evaluating the endochondral ossification, stage of development, and microscopic potential for normal growth.

Three fetuses between 28 and 30 weeks of gestation, one with classic bladder exstrophy, one with cloacal exstrophy, and one control, were obtained from France. The bony pelves were dissected and preserved in formalin, and multiple representative sections were sliced from all pelvic areas: pubis, ischium, ilium, and sacrum. These slices were sequentially processed as slides, stained with hematoxylin-eosin, and evaluated microscopically for histologic changes, developmental stage, and degree of endochondral ossification.

All slides from the three specimens showed cartilage analogue with endochondral ossification. Histologically the exstrophy specimens were identical to the control and appeared completely normal; bone development was occurring at an expected rate with the potential for continued normal growth.

These new findings illustrate that fetal bone in the exstrophy complex displays normal microscopic growth patterns and unhindered endochondral ossification at 28 weeks of gestation, well beyond the embryologic period. With no evident microscopic bony defect, the gross bony anomalies in exstrophy should be surgically correctable, leading us to conclude that early reapproximation of the physiologic shape of the pelvis could lead to more normal gross bone growth, decreased shortage of bone, and a more appropriate distribution of the mechanical and developmental forces on a closed, normally functioning pelvic ring.