[1] Univ Giessen, Dept Anat & Cell Biol, D-35392 Giessen, Germany
[2] Univ Giessen, Inst Clin Immunol & Transfus Med, D-35392 Giessen, Germany
[3] Univ Giessen, Fac Vet Med, Clin Obstet Gynecol & Androl Large & Small Anim, D-35392 Giessen, Germany
[4] Univ Giessen, Fac Med, Dept Obstet & Gynaecol, D-35392 Giessen, Germany
[5] Univ Edinburgh, MRC Ctr Reprod Hlth, Edinburgh, Midlothian, Scotland