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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.telfer@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=9640 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=96132 =B5m) (mean size 100 =B5m =B1 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 =3D 38) or
absence (n =3D 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 =B5m =B1 7.4) than
those grown in control medium (mean diameter 111 =B5m =B1 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.