The postnatal development of the spinal cord of the dog

The postnatal myelinization of the dorsal, lateral and vertral funiculi in the spinal cord of the dog occurs rapidly during the first three weeks of life, with the exception of the fasciculus gracilis and lateral corticospinal tract in which myelin is not complete until after five weeks. The ventral (motor) grey columns are more developed in younger animals than the corresponding dorsal columns. Both ventral and dorsal columns reach adult form by five weeks of age, but the lateral columns mature later. Only slight morphological differences were found in the rate of development of cervical and lumbar segments, the latter maturing a little later. These findings are compared with earlier studies in the cat, and correlated with observations on reflex and locomotor development of the dog.