Re-closure by the Skin Graft of the Surgically Induced Spinal Open Neural Tube Defect in Chick Embryos

OBJECTIVE: To investigate a re-closure capacity and chronological changes of re-closure, the histologic findings are observed after skin graft on surgically induced spinal open neural tube defect(ONTD) in chick embryos. METHODS: Embryos were divided into two groups: graft and control. In the embryos of the graft, a skin fragment from another chick embryo of embryonic day 7 was grafted on the ONTD immediately after neural tube incision. Embryos were re-incubated in ovo, up to postoperative days(PODs) 3, 5, 7, 10 and sacrificed. Rate of re-closure was compared according to the group of the embryo and the observation time point. Serial changes in histological appearance were observed to investigate whether the re-closured ONTDs regain normal shape. Statistical analysis was performed using the SAS and x2 test. RESULTS: On PODs 3, 5, 7, and 10, re-closure rates of the graft were 87, 60, 53 and 88%, and those of the control were 13, 0, 0 and 20%, respectively. They showed more frequent re-closure of ONTDs by the skin allograft in the graft than control. There was no statistical difference between the closure rates of adjacent POD subgroups. Some embryos of the closed groups revealed complete closure of the neural tube and there was no difference from the normal neural tube. CONCLUSION: Skin graft on the surgically induced ONTD in the embryonic period has a protective effect on the spinal cord. It is suggested that the prenatal skin graft on the lesions of fetal myelomeningocele might prevent repeated spinal cord damage.

Re-closure Capacity of Surgically Induced Open Neural Tube Defect in Chick Embryos

OBJECTIVE: To determine whether there is a re-closure capacity of the open neural tube defect(ONTD) and to characterize its re-closing process, the morphological changes and the re-closure rate of a surgically induced ONTD are examined chronologically in early chick embryos. METHODS: Embryos of Hamburger and Hamilton stage 18-19 were used. The posterior roof of the central canal in the closed neural tube was incised longitudinally at the wing bud level. The incision was 3 somites long, which was equivalent to approximately 0.8mm. Following surgery, the embryos were re-incubated in ovo for three or five days. The area of the incision was observed with a stereomicroscope. Some of them were examined histologically with the transverse section of the wing bud area. They were divided into two groups(POD 3 and POD 5) according to the re-incubation period at the time of sacrifice and then into two subgroups(re-closure and defect group) according to the presence of ONTD at the operative site. RESULTS: The results showed : 1) Re-closure of ONTD occurred in 58%(23/40) of POD 3 embryos and 46%(22/48) of POD 5 embryos. The difference of re-closure was not statistically significant. 2) Most of the re-closed neural tubes revealed no significant difference from the controls in the histological examination. 3) In POD 3 and 5 groups, there was a tendency of zipper-like fusion in both re-closure and defect groups. CONCLUSION: The results of study showed that the neural tube of the early chick embryo has a re-closure capacity after being surgically reopened. Seemingly, re-closure occurs mainly before POD 3 and progresses from the ventral to the dorsal part of the neural tube. The mechanism of re-closure needs to be investigated further.