There were the original 12 apostles that walked with Jesus and then there were at least 12 other apostles that are mentioned in the NT. There are 25 apostles mentioned if you count Jesus as the Apostle and High Priest of our confession.
We need apostles which simply means "sent ones" in order for the body of Christ to grow up. Sent ones are those commissioned and called of the Lord for a specific task concerning the proclaiming of the gospel and it seems to be mostly in the area of new places that have not heard the gospel.
We need to be under the influence of all 5 ministry gifts that the Lord gave to His body so that we could grow up in Him.
1 Corinthians 12:28 (KJV)
[SUP]28 [/SUP] And God hath set some in the church, first apostles, secondarily prophets, thirdly teachers, after that miracles, then gifts of healings, helps, governments, diversities of tongues.
Ephesians 4:11-13 (KJV)
[SUP]11 [/SUP] And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers;
[SUP]12 [/SUP] For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ:
[SUP]13 [/SUP] Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ: