1. Medical Research Council Research Unit for Molecular Reproductive Endocrinology (B.E.T.), Department of Medical Biochemistry, University of Cape Town, Observatory 7925
2. Department of Biochemistry (J.P.H)., University of Stellenbosch, Matieland 7602
3. Medical Research Council Reproductive Biology Unit (R.P.M.), Center for Reproductive Biology, Edinburgh, United Kingdom EH3 9ET
4. Department of Biochemistry (N.I.), University of Cape Town, Rondebosch 7700, South Africa