Human Reproduction 2008

A two-step serum-free culture system supports development of human
oocytes from primordial follicles in the presence of activin

Evelyn E. Telfer1,3, Marie McLaughlin1, Christina Ding2 and K. Joo
Thong2

1 Institute of Cell Biology, The Darwin Building, University of
Edinburgh, The King's Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
2 Assisted Conception Programme, The Royal Infirmary, 49 Little France
Crescent, Old Dalkeith Road, Edinburgh, UK

3 Correspondence address. Tel: +44-131-650-5393; Fax:
+44-131-650-8650; E-mail: evelyn.tel...@ed.ac.uk

BACKGROUND: The objective of this study was to determine whether
follicles grown within human ovarian cortical strip culture for 6 days
in serum-free medium could be isolated at the secondary stage of pre-
antral development and grown in vitro to the late pre-antral/early
antral stage during a 4 day culture period.

METHODS: Ovarian cortical biopsies were obtained from six women aged
26–40 years, with informed consent, during elective Caesarean section.
Small tissue slices of ovarian cortex, with underlying stromal tissue
removed, were cultured in serum-free medium for 6 days and at the end
of this period pre-antral (secondary) follicles were dissected from
the strips. Seventy-four intact pre-antral follicles ranging in size
(66–132 µm) (mean size 100 µm ± 3.4) were selected for further
culture. Follicles were placed individually within V-shaped microwell
culture plates in serum-free medium in the presence (n = 38) or
absence (n = 36) of 100 ng/ml of human recombinant activin A.

RESULTS: Pre-antral follicles grown for 4 days in the presence of
activin A grew to a larger size (mean diameter 143 µm ± 7.4) than
those grown in control medium (mean diameter 111 µm ± 8) (P < 0.005).
Ninety percent of follicles cultured in the presence of activin A
increased in size during the first 2 days of culture compared with
only 36% of follicles in control medium (P > 0.005). Of the follicles
surviving the entire culture period, 30% of those cultured in the
presence of activin A showed normal morphology with intact oocytes and
antral formation. None of the follicles grown in control medium
developed antral cavities and >90% of those follicles collected at the
end of the culture period showed signs of oocyte degeneration.

CONCLUSIONS: The results reported here demonstrate that under certain
conditions, it is possible to achieve accelerated oocyte/follicle
development from human primordial/primary follicles. This provides the
first encouraging step towards achieving full in vitro growth of human
oocytes.