A contraceptive method for living animals (including human beings) where a cap or disc (10) of cellular material provides an inert carrier matrix to support contraceptive preparations, the cap or disc (10) being engageable with the external os of the cervical canal. The contraceptive preparation which includes divalent and/or trivalent metal cations and L-ascorbic acid and/or neuraminidase cause the cervical mucus which comes into contact with the dose to change from an open cellular structure found at mid cycle of the menstrual period to a closed cellular structure which forms an impenetrable barrier for spermatozoa. The contraceptive preparation can further include asialoglycoprotein as an acceptor for spermatozoal sialic acid to prevent penetration and fertilization of ova by the spermatozoa. A subsidiary contraceptve property of the preparations is that they may be spermotoxic causing reformation of seminal plasma to trap the spermatozoa leading to their death due to acidity of the vagina (16).
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