A study of the effects of deafferentation of the brachial level of the spinal cord in chick embryos was undertaken to examine the influence of afferent input on activity patterns of the wings, during embryonic, hatching and posthatching periods. Neural crest precursors of dorsal root ganglia were destroyed by superficial cauterization at somite levels 17 to 21 in embryos of stages 13-14. Between nine and 17 days of incubation no significant differences were observed in the frequency of wing movements as part of either total or local activity patterns. The prehatching and hatching behavior patterns were typical except that none of the experimental embryos managed to tuck the head under the right wing (tucking phase). Wing lifting and lowering were absent between day 18 and hatching. In hatched chicks, wings were incable of making synchronous bilateral flapping movements. The results indicate that afferent input from the wings to the spinal cord is probably involved in the patterning of wing movements. In the absence of afferent input. the chick embryos show gross disturbances in the pattern of hatching and after hatching.The functional significance of spinal cord segments of limb levels has been studied extensively and the amount of neuroanatomical and behavioral studies that has gone into the elucidation of the mechanism is considerable (Szekely, '63, '68; Straznicky, '63; Narayanan and Hamburger, '71). In a preceding paper (Narayanan and Malloy, '74) we described the effect of deafferentation at hind limb levels on embryonic and posthatching activity of the legs in the chick. The bilaterally synchronized flapping movements of the wings in birds are in striking contrast to the alternating stepping movements of the legs. This paper deals with the effect of deafferentation at brachial levels on embryonic and posthatching activity patterns of the wings in the chick.
AnimalsFertile eggs of the Dekalb strain of white leghorns supplied by a commercial hatchery were used for this experiment. The eggs were incubated in a large, forced draft incubator at a temperature of 37.5" C and a relative humidity between 65 to 70%. Incubation was timed
MATERIALS AND METHODS
-,behavior involving the wings during from approximately two hours after the eggs had been placed in the incubator in order to allow them sufficient time to attain incubating temperature.Operative procedure Techniques used to prepare embryos for microsurgery were essentially those described previously (Narayanan, '70). All operations were performed on embryos of stages 13-14 (Hamburger and Hamilton, '51). The neural crest precursors of the dorsal root ganglia at brachial levels were destroyed by superficial cauterization using a concept "C" size unit (Narayanan and Malloy, '74). Sham operations on control embryos consisted of staining, cutting the vitelline membrane and staging. After the operations, the window was closed with a sterilized cover glass, sealed with hot paraffin, and the eggs were returned to the incubator.
Recordings of motilityThe recordi...
