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Relationship between age of blastocyst formation and interferon‐τ secretion by in vitro–derived bovine embryos
Author(s) -
Kubisch H. Michael,
Larson Melissa A.,
Roberts R. Michael
Publication year - 1998
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/(sici)1098-2795(199803)49:3<254::aid-mrd5>3.0.co;2-n
Subject(s) - columbia university , library science , biology , media studies , sociology , computer science
This study was designed to examine the relationship between the speed at which bovine embryos reach the blastocyst stage, their cell number, and interferon‐τ production. A total of 800 oocytes were fertilized by frozen‐thawed semen. On day 2, 44 hr after exposure to sperm, 78, 320, and 296 embryos were at the two‐, four‐, and eight‐cell stages, respectively, with an overall cleavage rate of 86.8%. Within these three groups 15 (19.2%), 106 (33.1%), and 158 (53.4%) embryos proceeded to the blastocyst stage. Of these 46.7%, 65.1%, and 63.3% hatched in the three groups, respectively. Blastocysts began to appear at day 7, but a few did not form until as late as day 13. Expanded blastocysts ( n = 279) were cultured individually for 48 hr in 50‐μl droplets of medium, fixed for cell counts, and the concentration of interferon‐τ in the medium was determined. Blastocysts originating from two‐cell embryos had significantly fewer cells (46.5 ± 23.3) than either four‐cell‐ (97.2 ± 13.5) or eight‐cell‐derived embryos (113.8 ± 13.6; P < 0.05). Hatching was accompanied by an increase in cell number (129.8 ± 15.5 versus 41.9 ± 14.4; P < 0.01). Blastocysts derived from embryos that had reached the eight‐ or four‐cell stage 44 hr after insemination produced significantly more interferon than embryos derived from two‐cell embryos (941.7 ± 92.1, 930.1 ± 163.1, versus 232.8 ± 70.1 pM). In contrast, hatching, ovary batch, the speed of early cleavage, cell number, and quality grade had no effect on interferon‐τ secretion. The embryo's age at blastocyst formation was not related to the number of its cells but did have a significant effect ( P < 0.001) on interferon‐τ production, with mean concentrations in the medium of 294.8 ± 57.9, 563.3 ± 82.0, 1126.3 ± 133.6, 1778.5 ± 297.2, 512.9 ± 82.0, 315.0 ± 157.5, and 157.5 pM among blastocysts appearing from days 7 to 13, respectively. These data suggest that blastocysts that form at days 7 and 8 produce less interferon‐τ than those that form on days 9 or 10. Since early‐forming blastocysts are generally considered more developmentally competent than those which form late, there may be a negative relationship between early interferon‐τ production and competence. Mol. Reprod. Dev. 49:254–260, 1998. © 1998 Wiley‐Liss, Inc.