Two Cases of 8 Cervical Vertebrae in the Porcupine and the Paca

Abstract

8 cervical vertebrae is rare change and there are little reports in it's figure. Two cases of 8 cervical vertebrae were found in a series of 2 porcupines(Hystrix cristata)and 5 pacas(Agouti paca). The vertebral formula of normal porcupine is 7 cervical vertebrae, 15 thoracic vertebrae, 4 lumbar vertebrae, 4 sacrum vertebrae, 14 caudal vertebrae, but 8 cervical vertebrae specimen reduced one thoracic vertebra. It seems that 8 cervical vertebrae of porcupine may be occurred single homeotic transformation by Hoxb-5 or Hoxa-6. Although the normal paca's vertebrae formula is 7 cervical vertebrae, 13 thoracic vertebrae, 6 lumbar vertebrae, 5 sacrum vertebrae, 7 caudal vertebrae, but 8 cervical vertebrae specimen reduced one lumbar vertebra. It seems that 8 cervical vertebrae of paca may be occurred double homeotic transformations by Hoxb-5 or Hoxa-6 and from Hoxc-6 to Hoxa-10.