Hum. Reprod. Advance Access originally published online on October 11, 2007
Human Reproduction 2008 23(1):37-45; doi:10.1093/humrep/dem178
Human immature oocytes grow during culture for IVM
1 Centre for Reproductive Medicine, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, CV2 2DX, UK 2 Laboratory of Reproductive Biology, Juliane Marie Centre, Section 5712, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark 3 Clinical Sciences Research Institute, Warwick Medical School, University of Warwick, Clifford Bridge Road, Coventry, CV2 2DX, UK
5 Correspondence address. Tel: +44-2476-968697/528382; Fax: +44-2476-968653; E-mail: geraldine.hartshorne{at}warwick.ac.uk
BACKGROUND: Oocyte competence for maturation and embryogenesis is associated with diameter in many mammals. We aimed to test whether this relationship exists in humans and to quantify its impact upon in vitro maturation (IVM).
METHODS: We used computer-assisted image analysis daily to measure average diameter, zona thickness and other parameters in oocytes. Immature oocytes originated from unstimulated patients with polycystic ovaries, and from stimulated patients undergoing intracytoplasmic sperm injection (ICSI). Some were cultured with meiosis activating sterol (FF-MAS). Matured oocytes were inseminated using ICSI and embryo development was monitored. In vivo matured oocytes were also measured.
RESULTS: Immature oocytes were smaller at collection than in vivo matured oocytes. Maturation was related to oocyte diameter and many oocytes grew in culture. FF-MAS stimulated growth in oocytes derived from ICSI patients, but only stimulated growth in PCO derived oocytes if they matured in vitro. Degenerating oocytes showed cytoplasmic shrinkage. Neither zona thickness, perivitelline space, nor the total diameter of the oocyte plus zona were informative regarding maturation capacity.
CONCLUSIONS: Immature oocytes grow during maturation culture. FF-MAS promotes oocyte growth in vitro. Oocytes from different sources have different growth profiles in vitro. Measuring oocytes in clinical IVM may provide additional non-invasive information that could potentially avoid the use of growing oocytes.
Key words: diameter/growth/human/IVM/oocyte
4 Present address: Assisted Conception Unit, Kings College Hospital, Denmark Hill, London, SE5 9RS, UK