Angiogenesis during implantation, and placental and early embryonic development

Angiogenesis, the development of new capillaries from pre-existing vessels, is induced by inflammation, wound healing, immune reactions and neoplasia, and is required for tumour growth and progression. Angiogenesis participat es in a wide range of ovulatory-related and non-ovulatory-related reproduct ive processes. We present a review of current data pertaining to angiogenes is of pregnancy, with specific emphasis on implantation and placental and e mbryonic development in both normal physiology processes and various pathol ogical conditions. To this goal, MEDLINE, Current Contents and Index Medicu s were searched for studies published between 1966 and August 1999. Pertine nt studies (including human and animal models) pertaining to angiogenesis o f implantation and placental and embryonic development were reviewed. Curre nt literature supports that angiogenesis is an essential physiological comp onent of implantation, and placental and embryonic development. Angiogenesi s also actively participates in abnormal implantation, and various patholog ical processes of the placenta including those observed in association with pre-eclampsia, growth restriction, maternal anaemia in the first-trimester and other hypoxia-related conditions during pregnancy. Finally, administra tion of an angiogenesis inhibitor (AGM-1470) in mice has been shown to resu lt in complete failure of embryonic growth due to interference with decidua lization, placental and yolk sac formation, and embryonic vascular developm ent. (C) 2001 Harcourt Publishers Ltd.