LetAbe an artin algebra. Let Γ be a component of the Auslander-Reiten Quiver ΓAand Γ contain no oriented cycle. If Γ is stable or semi-stable, then the structure of Γ is known. Here, we are going to consider general component which may contain both injective vertices and projective vertices at the same time. We will show that Γ can be embedded in some Δ with Δ isomorphic to a section of Γ if and only if every possible path from an injective vertex to a projective vertex is sectional. This result generalizes part of Zhang’s theorem and the corresponding part of Liu’s theorem.