STIMULATION OF PROGESTERONE PRODUCTION IN BOVINE LUTEAL CELLS BY COINCUBATION WITH BOVINE BLASTOCYST-STAGE EMBRYOS OR TROPHOBLASTIC VESICLES

A study was conducted to determine whether bovine blastocyst-stage emb ryos and trophoblastic vesicles stimulate the production of progestero ne in bovine luteal cells during incubation in vitro. The effects of c o-incubation of these embryos and vesicles with uterine endometrial ti ssue on progesterone production was also investigated. Bovine small an d large luteal cells were obtained on day 12 of the oestrous cycle, di spersed by unit gravity sedimentation and recombined to provide prepar ations free of accessory cells. Blastocyst-stage embryos were obtained on day 7 and trophoblastic vesicles were obtained from bovine embryos on day 12. A uterine endometrial tissue sample was obtained from the same cow from which the corpus luteum was taken. Treatment groups were arranged in 24-well plates as follows: luteal cells alone; luteal cel ls and one trophoblastic vesicle; luteal cells and one blastocyst embr yo; luteal cells and a 10 mg uterine endometrial sample; luteal cells, one trophoblastic vesicle and a uterine endometrial sample; and lutea l cells, one blastocyst embryo and a uterine endometrial sample. All t reatment groups were incubated (at 37 degrees C under 5% CO2) in Ham's F-12 medium supplemented with antibiotics (100 mu g penicillin ml(-1) and 100 U streptomycin ml(-1), L-glutamine (0.29 mg ml(-1)), insulin (5 mu g ml(-1)), transferrin (5 mu g ml(-1)) and selenium (5 ng ml(-1) ) for 12 h. Samples of the medium were harvested 10 min (basal concent ration) and 2, 6 and 12 h after incubation to determine the concentrat ions of progesterone and prostaglandin. The major findings of this stu dy were that both trophoblastic vesicles and blastocyst-stage embryos stimulated progesterone production during the 12 h incubation. In addi tion, the uterine endometrial sample partially inhibited the stimulato ry actions of trophoblastic vesicles and blastocyst embryos after 12 h of incubation.