[1] IMPERIAL CANC RES FUND, DEPT HISTOPATHOL, LONDON WC2A 3PX, ENGLAND
[2] UNIV NOTTINGHAM HOSP, DEPT HISTOPATHOL, NOTTINGHAM NG7 2UH, ENGLAND
[3] UCL, SCH MED, DEPT HISTOPATHOL, LONDON W1N 8AA, ENGLAND
[4] UCL, SCH MED, DEPT CYTOL, LONDON W1N 8AA, ENGLAND
[5] UNIV COLL & MIDDLESEX SCH MED, DEPT OBSTET & GYNAECOL, LONDON, ENGLAND
[6] MARGARET PYKE CTR FAMILY PLANNING & REPROD HLTH C, LONDON, ENGLAND