INHIBITION OF OESTROUS BEHAVIOUR IN EWES BY PASSIVE IMMUNIZATION AGAINST OESTRADIOL-17β

M.R.C. Unit of Reproductive Biology, Department of Obstetrics and Gynaecology, University of Edinburgh, 39 Chalmers Street, Edinburgh EH3 9ER (Received 14th June 1974) The biological activity of a steroid can be readily neutralized by high-affinity antibodies directed against the steroid, thus providing a useful method of studying its effects. Biological neutralization with antibodies to low molecular weight hormones can be produced either by active immunization against an hormonal hapten (Scaramuzzi, Caldwell, Tillson & Thorneycroft, 1970), or by the passive transfer of antibodies to the hormone (Vande Wiele, Ferin, Raziano, Dyrenfurth & Mikhail, 1970). The widespread use of these methods has not been possible in the past because of difficulties in generating antisera to steroid haptens and the relatively small quantities of antisera produced. The availability of reliable quick methods for the production of antisera to hormones of low molecular weight (Vaitukaitis, Robbins, Nieschlag & Ross, 1971) has been reflected by