In property law, a conveyance by the owner O "To A and heirs of the body", without more, creates a fee tail for the grantee (A) with a reversion in the grantor (O) should the natural, lawful descendants of the grantee all die out.
In property law, a transfer by the owner O "To A and heirs of the body" establishes a fee tail for A, accompanied by a reversion in O when A's direct lineage disappears.