Spinal congenital dermal sinus in a chick embryo model. Laboratory investigation.

OBJECT

The origin of spinal congenital dermal sinuses is not known. A local nondisjunction of the closing neural tube and the epidermal ectoderm is thought to be the cause of this malformation. In this experimental study, a nondisjunction was mimicked in chick embryos to create an animal model for the dermal sinus.

METHODS

A piece of amniotic tissue was implanted in the closing neural tube in ovo in chick embryos at 2 days of incubation. A total of 50 embryos were manipulated. After a further incubation time of 2-7 days, the embryos were macroscopically and histologically evaluated.

RESULTS

Dermal sinus-like anomalies were induced in 24 embryos. The induced abnormalities varied from superficial, epidermal lesions to epidermal dimples continuing as a strand of tissue toward the neural tube. This strand invariably was of nonneuronal origin. Additionally, in 3 embryos a split cord malformation was noted, most likely caused by damage to the neural tube during implantation.

CONCLUSIONS

Implantation of donor amniotic tissue in the closing chick neural tube does result in a dimple, from which a strand of tissue continues to the neural tube in various cases, indicating that formation of a dermal sinus-like anomaly can be successfully induced by experimental continuation of the connection between neural tube and surface ectoderm. This finding strengthens the hypothesis that a human dermal sinus arises after nondisjunction of neural tube and surface ectoderm.