Which embryologic defect is implicated in the development of congenital dermoids in Rhodesian ridgebacks?

Which embryologic defect is implicated in the development of congenital dermoids in Rhodesian ridgebacks?

• A. Neural tube closure defect
• B. Spinal bifida occulta
• C. Forebrain malformation
• D. Neural crest migration defect

Answer: (A)

Dermoid lesions in Rhodesian Ridgebacks come from a problem in neurulation, when the surface ectoderm fails to properly separate from the neural ectoderm as the neural tube forms. This incomplete separation allows ectodermal tissue to persist as a tract that extends from the skin toward the spinal canal, creating a dermoid sinus along the dorsal midline. That kind of failure is best described as a neural tube closure/neurulation defect. Spinal bifida occulta is a vertebral-arch closure issue, not the direct cause of a midline dermoid tract. Forebrain malformation isn’t related to a dorsal, midline dermoid, and neural crest migration defects affect different tissues and structures.

Dermoid lesions in Rhodesian Ridgebacks come from a problem in neurulation, when the surface ectoderm fails to properly separate from the neural ectoderm as the neural tube forms. This incomplete separation allows ectodermal tissue to persist as a tract that extends from the skin toward the spinal canal, creating a dermoid sinus along the dorsal midline. That kind of failure is best described as a neural tube closure/neurulation defect. Spinal bifida occulta is a vertebral-arch closure issue, not the direct cause of a midline dermoid tract. Forebrain malformation isn’t related to a dorsal, midline dermoid, and neural crest migration defects affect different tissues and structures.