CT analysis and gross appearance of the repair of the goat skull defect. a1–a3 3D reconstruction of the CT of the cranial defect location repaired by Fetal-TEBG in young goats, 1.5 months, 3 months, 6 months. a4 General view of the cranial defect location repaired by Fetal-TEBG in young goats. b1–b3 3D reconstruction of the CT of the cranial defect location repaired by Control DBM scaffold in young goats, 1.5 months, 3 months, 6 months. b4 General view of the cranial defect location repaired Control DBM scaffold in young goats. c1–c3 3D reconstruction of the CT of the cranial defect location repaired by Fetal-TEBG in aged goats, 1.5 months, 3 months, 6 months. c4 General view of the cranial defect location repaired Fetal-TEBG in aged goats. d1–d3 3D reconstruction of the CT of the cranial defect location repaired by Control DBM scaffold in aged goats, 1.5 months, 3 months, 6 months. d4 General view of the cranial defect location repaired Control DBM scaffold in aged goats. e1, e2 1.5 months: the bone volume (BV) and bone volume/tissue volume ratio (BV/TV) in the skull defect area of Fetal-TEBG/Young group was more than that of Fetal-TEBG/Aged group (p < 0.05); In the Control DBM groups, the bone volume (BV) and bone volume/tissue volume ratio (BV/TV) of the young goats was also significantly higher than that of the aged goats (p < 0.05). f1, f2 3 months: the bone volume (BV) and bone volume/tissue volume ratio (BV/TV) in the skull defect area of Fetal-TEBG/Young group was more than that of Fetal-TEBG/Aged group (p < 0.05); In the Control DBM groups, the bone volume (BV) of the young goats was also significantly higher than that of the aged goats (p < 0.05). g1, g2 6 months: the bone volume (BV) and bone volume/tissue volume ratio (BV/TV) in the skull defect area of Fetal-TEBG/Young group was more than that of Fetal-TEBG/Aged group (p < 0.05); In the Control DBM groups, the bone volume (BV) and bone volume/tissue volume ratio (BV/TV) of the young goats was also significantly higher than that of the aged goats (p < 0.05)