Some glandular extracts also contain small, safe amounts of hormones that may contribute to their possible effectiveness. The thymus gland contains thymic hormones which Schulof found may enhance immune response for people with HIV . It should be noted that many substances contained within animal tissues are similar or identical to their human counterparts [1,25-27], including certain enzymes  and even T cell gene regions . One advantage of glandulars over herbs is that raw ovine (sheep) and bovine (cow) glandulars often contain enzymes that are identical to those in the human body, while herbs rarely do.
The structure of oxytocin is very similar to that of vasopressin . Both are nonapeptides with a single disulfide bridge, differing only by two substitutions in the amino acid sequence (differences from oxytocin bolded for clarity): Cys – Tyr – Phe – Gln – Asn – Cys – Pro – Arg – Gly – NH 2 .  A table showing the sequences of members of the vasopressin/oxytocin superfamily and the species expressing them is present in the vasopressin article. Oxytocin and vasopressin were isolated and their total synthesis reported in 1954,  work for which Vincent du Vigneaud was awarded the 1955 Nobel Prize in Chemistry with the citation: "for his work on biochemically important sulphur compounds, especially for the first synthesis of a polypeptide hormone."