ABSTRACT
Medical practice involving human embryos involves the assisted reproductive technologies. Initially a woman’s own eggs and her partner’s own sperm were used to create embryos. The first experiments developed the technique of natural cycle in vitro fertilisation (IVF) where the woman’s own natural single dominant follicle yielded only a single egg. Because of poor success rates gonadotrophin stimulation was used to overcome the natural control mechanisms and create multiple follicles yielding multiple eggs, perhaps 10–15 in each cycle. Variable control of the natural mid-cycle trigger to ovulation led to its interference in optimum harvesting of embryos so this mid-cycle luteinising hormone surge was switched off by a gonadotrophin releasing hormone agonist leading to greater follicle development and the harvesting of even 20–30 eggs. Donor gametes may be used leading to a further three combinations, donor eggs and own sperm, own eggs and donor sperm or both donor sperm and eggs. Donors may be unknown which is usual for sperm, although Sweden, Denmark and New Zealand have introduced legislation to reveal donor identity. Donated eggs have more frequently arisen from known donors, altruism being a common feature of egg donation and in some ethnic groups poorly represented in a particular country, there may be no alternative but to have a known donor. In France ‘relational’ egg donors are widely used where the potential recipient brings along a donor but the donor’s eggs are used for someone else so that the recipient receives an unknown donor’s eggs.
