The critical period for the maternal recognition of pregnancy in pony mares
Hershman, L.; Douglas, R.H.
Journal of Reproduction and Fertility. Supplement 1979(27): 395-401
1979
ISSN/ISBN: 0449-3087 PMID: 289816 Document Number: 140623
Two experiments were performed to determine the critical time at which the equine blastocyst must be present within the uterus of the mare to prevent regression of the corpus luteum, and thereby to establish the critical time for the maternal recognition of pregnancy. A non-surgical technique for blastocyst collection was developed to study this relationship between the blastocyst and the maternal ovary. The results from these experiments demonstrated that the cyclic lifespan of the corpus luteum is not affected by the presence of the blastocyst within the mare's uterus until after day 14 following ovulation. Luteal function was prolonged when blastocysts were removed on day 15 or later. The critical period for the maternal recognition of pregnancy in the pony mare appears to be confined to the period between days 14 and 16 after ovulation.