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This experiment was conducted to determine the effects of trophoblastic vesicles (TV) and estradiol-17beta on the development in vitro of rabbit embryos. Thirty matured female rabbits were treated with PMSG followed by HCG injection and mating. Embryos were recovered with D-PBS (Dulbecco’s Phosphate Buffered Saline) after superovulation, and normally developed to two-to four-cell embryos were used in the subsequent in vitro culture. Basal medium was Medium-199 su, pp.emented with 1.5% bovine serum albumin. Embryo on Day 5 after mating (Day 0) was cut into two or three pieces to remove the embryonic disc. Each piece of tissue was cultured for 24 hours at 37^{circ}C in 0.5 mlMedium-199 in 5% CO2. During culture, peices of trophoblastic tissue changed into spherical vesicles which were used for co-culture. These spheres were called trophoblstic vesicles. Two-to four-cell embryos were cultured for 4 days in Medium-199 in the absence or presence of trophoblastic vesicle, and two-to four-cell embryos cultured with varing concentration (0, 0.1, 1, 10ng/ml) of estradiol-17beta for 4 dyas. Culture vessels used were watch glass for coculture with trophoblastic vesicles and micortube for estradiol-17beta infusion. Compared with the Medium-199 alone as basal culture medium, more blastocysts (46.7% vs 15.1%; P<0.01) and morulae (84.4% vs 56.6%; P<0.05) were developed in the co-culture with trophoblastic vesicles. Estradiol-17beta infused in culture medium was not effective for embryo development to blastocysts (78.3% in control, 50.0% in 0.1ng/ml, 61.5% in 1ng/ml and 64.4% in 10ng/ml) and also to morulae (91.3% in control, 84.2% in 0.1ng/ml, 92.3% in 1ng/ml and 91.1% in 10ng/ml). Compared with the watch glass culture mehotd, more (P<0.01) blastocysts were developed in microtube culture (78.3% vs 56.6%) and more (P<0.01) morulae in microtube culture (91.3% vs 56.6%).
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