Christ's body in the Resurrection was "of the same nature, but differed in glory." Accordingly, whatever goes with the nature of a human body, was entirely in the body of Christ when He rose again. Now it is clear that flesh, bones, blood, and other such things, are of the very nature of the human body. Consequently, all these things were in Christ's body when He rose again; and this also integrally, without any diminution; otherwise it would not have been a complete resurrection, if whatever was lost by death had not been restored. Hence our Lord assured His faithful ones by saying (Mat. 10:30): "The very hairs of your head are all numbered": and (Lk. 21:18): "A hair of your head shall not perish."
But to say that Christ's body had neither flesh, nor bones, nor the other natural parts of a human body, belongs to the error of Eutyches, Bishop of Constantinople, who maintained that "our body in that glory of the resurrection will be impalpable, and more subtle than wind and air: and that our Lord, after the hearts of the disciples who handled Him were confirmed, brought back to subtlety whatever could be handled in Him" [St. Gregory, Moral. in Job 14:56]. Now Gregory condemns this in the same book, because Christ's body was not changed after the Resurrection, according to Rom. 6:9: "Christ rising from the dead, dieth now no more." Accordingly, the very man who had said these things, himself retracted them at his death. For, if it be unbecoming for Christ to take a body of another nature in His conception, a heavenly one for instance, as Valentine asserted, it is much more unbecoming for Him at His Resurrection to resume a body of another nature, because in His Resurrection He resumed unto an everlasting life, the body which in His conception He had assumed to a mortal life.
See Summa Theologica (Tertia Pars, Quest. 54, Art. 3)