According to Matthew, at a time not specified, Jesus appeared to the eleven on a mountain in Galilee (Matt. XXVIII:16), "and when they saw Him, they worshipped Him; _but some doubted_" (Matt. XXVIII:17). Now, from this it is apparent: first, that Jesus did not appear in His natural, earthly form, for then the eleven would at once have recognized His identity; and, second, that we have no means of telling just how many of the eleven would have testified to this being an appearance of the true Jesus, since "some" doubted.
John's original Gospel warrants appearances of Jesus, first, to Mary Magdalene, the other Mary not being with her (John XX:15, 16, 17); second, an appearance on Sunday evening to the apostles, except Thomas (John XX:19); third, an appearance eight days later to all the eleven apostles (John XX:26). Nothing is said about any ascension.
John's Chapter XXI, which, as has been said, appears clearly to have been a later addition to the original Gospel, relates an appearance of Jesus in Galilee, which is materially different from that of Matthew. The appearance is not on a mountain, but on the shores of the sea of Tiberias, and, instead of the eleven apostles being present, there were, at most, only seven, including Nathaniel of Cana (John XXI:2). All of them have considerable trouble in recognizing Jesus (John XXI:4, 12). Nothing is said by Jesus about baptizing, or preaching to, the Gentiles, but, on the contrary, Jesus tells Peter to feed "my sheep," or "my lambs" (John XXI:15, 16, 17). Nothing is said about any ascension of Jesus into heaven.
The Gospels of Mark and Luke, the original Gospel of John, and the Acts, all agree in fixing the after-death appearances and ascension of Jesus in Jerusalem or its neighborhood (Luke XXIV:50; Acts I:12). Apparently the apostles remained for some time in Jerusalem after the Crucifixion (possibly for forty days, Acts I:3; II:1), until they separated and "went forth and preached everywhere" (Mark XVI:20). In the Acts it is said that Jesus "commanded" them to remain in Jerusalem, until the gift of the Holy Ghost should be sent to them (Acts I:4).
It is evident, in all these accounts, that the apostles had never understood, or had entirely forgotten, the predictions of Jesus in His lifetime that He would rise from the dead (Matt. XVI:21; XVII:23; XX:19; Mark VIII:31; IX:31; X:34; Luke IX:22; XVIII:33). They were not expecting any resurrection. They were not waiting at the tomb for it to occur, and, by the unanimous testimony of all the writers, they showed the greatest surprise and incredulity at the first reports of Jesus' appearance alive (Matt. XXVIII:17; Mark XVI:11, 13; Luke XXIV:11, 16, 37, 41; John XX:9, 14, 25).