Sp. Brinsko et al., IN-VITRO DEVELOPMENT OF DAY-2 EMBRYOS OBTAINED FROM YOUNG, FERTILE MARES AND AGED, SUBFERTILE MARES, Journal of Reproduction and Fertility, 102(2), 1994, pp. 371-378
This study was designed to investigate the development of day 2 embryo
s obtained from young and aged mares, co-cultured with oviductal epith
elial cells obtained from mares in each age group in a 2 x 2 crossover
design. Young, fertile mares (n = 19; 2-7 years of age) and aged, sub
fertile, mares (n = 16; 17-24 years of age) were used as embryo and ov
iductal epithelial cell donors. Embryos (n = 37) were collected from t
he oviducts 2 days after ovulation and were paired (embryos obtained f
rom young mares with embryos obtained from aged mares) so that eight p
airs were co-cultured with young mare oviductal epithelial cells and e
ight pairs were co-cultured with aged mare oviductal epithelial cells.
Five additional embryos obtained from young mares were co-cultured wi
th oviductal epithelial cells from either young mares or aged mares bu
t were not paired. Embryos were co-cultured for 7 days at 38.5 degrees
C in 5% CO2 or until morphological degeneration was detected. The pro
portions of paired embryos that reached the blastocyst stage were simi
lar for embryos obtained from young mares and embryos obtained from ag
ed mares after co-culture with oviductal epithelial cells from young m
ares (6 of 8 versus 5 of 8) or from aged mares (6 of 8 versus 5 of 8),
respectively. Although the overall rate of development of embryos to
blastocyst from both young mares and aged mares was similar, blastocys
ts developing from embryos obtained from aged mares were inferior to b
lastocysts obtained from young mares in terms of number of cell nuclei
, quality score, and diameter at day 7. The results of this experiment
indicate that the high rate of early embryonic loss in aged, subferti
le mares may be due to inherent developmental defects in their embryos
, but does not appear related to the ability of embryos from aged, sub
fertile mares to reach the blastocyst stage.