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This experiment was designed to determine whether the stimulatory effects of bovine oviductal epithelial cells (BOEC) on development of early bovine embryos are due to platelet-derived growth factor (PDGF). Four hundred and twenty five 8-cell bovine embryos derived from in vitro maturation and in vitro fertilization procedures were equally and randomly allotted to one of the following culture treatment groups: control medium alone (Menezo's B2 medium; MB2), MB2 with 1 ng PDGF ml-1 (PDGF), 1 ng PDGF ml-1 and 10 micrograms anti-PDGF antibody ml-1 (PDGF + Ab), BOEC or BOEC and 10 micrograms anti-PDGF antibody ml-1 (BOEC + Ab). All embryos were cultured in 100 microliters of serum-free MB2 medium supplemented with 2 mg fatty-acid-free bovine serum albumin ml-1. Embryos for all treatment groups were incubated at 39 degrees C and 5% CO2 in humidified air in groups of five embryos per well in 96-well culture plates until 7 days after in vitro insemination. A higher proportion of embryos developed to > 8-cell and to the morula stage following culture with PDGF, BOEC or BOEC+Ab than with MB2 alone. Incubation of PDGF and BOEC-treated embryos with anti-PDGF reduced development to the morula and blastocyst stages. However, anti-PDGF did not completely inhibit blastocyst development when added to BOEC. In addition, embryos incubated with BOEC and anti-PDGF contained a reduced number of inner cell mass cells compared with embryos incubated with BOEC alone. These results indicate that PDGF provides a developmental stimulus similar to BOEC for bovine embryos at the fourth cell cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

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A study was conducted to determine the effects of pregnancy-specific protein B (PSPB) and prostaglandin F2 alpha (PGF2 alpha) on bovine luteal cell progesterone, prostaglandin E2 (PGE2) and oxytocin production in vitro. Corpora lutea were enucleated from multiparous cows with normal oestrous cycles during the mid-luteal (days 10-12; n = 5) or late-luteal (days 17-18; n = 5) stage. Mixed large and small cells (1.5 x 10(5) cells per well) were incubated in 500 microliters modified Ham's F-12 medium. Cells were incubated for 18 h before treatments were added. Cells were treated with PSPB (0, 2.5, 5.0 micrograms) and PGF2 alpha (0, 100, 200 ng) in a 3 x 3 factorial arrangement. After treatments were added, media samples were collected at 6 and 12 h. During the 18 h pretreatment incubation, progesterone, PGE2 and oxytocin production was similar between the prospective treatment groups. Progesterone production was greater (P < 0.001) by mid-stage than by late-stage cells. In addition, progesterone decreased (P < 0.001) as incubation time increased. Progesterone production was not affected by PGF2 alpha, but PSPB increased (P < 0.02) progesterone at the 5.0 micrograms dose. Late-stage luteal cells produced more (P < 0.001) PGE2 than did mid-stage cells; PGE2 production decreased (P < 0.001) with increased incubation time. Luteal PGE2 production increased in response to PSPB treatment (P < 0.01) and PGF2 alpha treatment (P < 0.001). Luteal oxytocin production was greater (P < 0.01) by mid-stage compared with late-stage cells. Oxytocin production decreased (P < 0.001) with incubation time in mid-stage cells, but in late-stage cells oxytocin production was similar over time. Neither PSPB nor PGF2 alpha had an effect on oxytocin. These results indicate that PSPB does not affect luteal oxytocin, but does increase progesterone and PGE2 production. In addition, PGF2 alpha increases luteal PGE2, but does not affect progesterone or oxytocin production. These data do not show an interaction between PSPB and PGF2 alpha in regulating bovine luteal cell endocrine function.