British Journal zyxwvuts of Obstetrics and Gynaecology zyxwvut February 1984, Vol. 91,pp. 148-154 The recovery of pre-ovulatory oocytes using a fixed schedule of ovulation induction and follicle aspiration ALLAN TEMPLETON, PAUL VAN LOOK, MARY ANNE LUMSDEN, ROSLYN ANGELL, JOHN AITKEN, ANDREW W. DUNCAN zyxw & DAVID T. BAIRD Department zyxwvu o f Obstetrics and Gynaecology, andMRC Unit of Reproductive Biology, Centre for Reproductive Biology, 37 Chalmers Street, Edinburgh EH3 9E W, Scotland zyxwvut Summary. Thirty-two volunteer women, scheduled for laparoscopy, were subjected to a fixed regimen of ovulation induction and ovarian follicle aspiration, following manipulation of the previous menstrual cycle with oral contraceptive pills or norethisterone. This allowed the time of oocyte recovery to be planned several weeks in advance. The recovery rate of mature oocytes (loosely dispersed cumulus) in the patients who had their cycles adjusted with norethisterone was comparable to that in a group of women treated in an embryo-transfer programme who were being individually monitored, although there was evidence from cleavage rates and concentration of sex steroids in follicular fluid that further follicular maturation could have occurred. It is suggested that a modification of this schedule could provide an acceptable recovery rate of pre-ovulatory oocytes for research purposes, and possibly by simplifying the monitoring technique could be applicable to a wider range of patients seeking embryo transfer. The major problems constraining research in human in-vitro fertilization are the limited supply of human oocytes for study and the difficulties in pre-determining the day and time of follicle aspiration. It seems unlikely that embryo-transfer programmes will generate sufficient spare embryos for research purposes, now that there is good evidence that the possibility of successful implantation increases with the number of embryos replaced (Trounson 1982; Jones 1982; Fishell 1982). Besides there remain ethical problems as to the disposal of embryos which have been recovered and fertilized for the express purpose of uterine transfer (Medical Research Council 1982). Furthermore the necessity of monitoring follicular growth by repeated measurements of oestradiol, luteinizing hormone (LH) and follicular diameter in individual patients, imposes severe problems in organizing oocyte recovery. Despite these difficulties there is an urgent need for a supply of human oocytes to study the effect of the stage of follicular develop- I48 ment, methods of recovery and conditions of culture on the development of embryos zy in vitro. Specifically there is a need to discover the incidence of chromosomal abnormalities in embryos which appear morphologically normal and are cleaving at ‘normal’ rates. We have investigated the possibility of obtaining oocytes from volunteers undergoing laparoscopic sterilization or having routine laparoscopy for infertility investigations. The day and time of laparoscopy was planned several weeks in advance by subjecting the women to a fixed regimen of ovulation induction and follicle aspiration. Synchronization was achieved by adjusting the menstrual cycle preceding the treat- ment cycle with extra oral contraceptive pills or with norethisterone. Patients and methods Patients were recruited from the gynaecological clinics where the implications of the study were