
%0 Journal Article
%A Block, J. 
%A Bonilla, L. 
%A Hansen, P. J. 
%T 123 OPTIMIZATION OF CULTURE CONDITIONS FOR <i>IN-VITRO</i>-PRODUCED BOVINE EMBRYOS TO ENHANCE BLASTOCYST YIELD AND SURVIVAL FOLLOWING VITRIFICATION
%J Reproduction, Fertility and Development
%D 2007/12/12
%V 20
%N 1
%P 142-142
%K 
%R https://doi.org/10.1071/RDV20N1AB123
%U https://www.publish.csiro.au/paper/RDV20N1AB123 
%X Objectives were to identify modifications in culture conditions that improve blastocyst yield and cryosurvival. The objective of Experiment 1 was to determine effects of sequential culture and fructose on blastocyst yield. Embryos were cultured in modified SOF with 4 mg mL&#8211;1 bovine serum albumin (BSA) and 1.0 mm alanyl-glutamine in 5% (v/v) oxygen with or without 0.5 mm fructose in either a static or sequential culture system. For the sequential system, embryos >4 cells were selected and placed in fresh drops of medium at day 3 after insemination. Culture system and fructose did not affect cleavage rate or the proportion of embryos >4 cells on day 3. The proportion of >4 cell embryos that developed to the blastocyst stage was higher (P  < 0.04) for static culture than for sequential culture (41.6 ± 1.2 v. 30.6 ± 1.2%) and there was a trend (P  = 0.1) for the proportion of oocytes that developed to blastocyst at day 7 to be greater for static culture (26.8 ± 1.2 v. 20.9 ± 1.2%). In both culture systems, fructose increased (P  < 0.03) blastocyst yield from embryos >4 cells (32.5 ± 1.2 v. 39.7 ± 1.2%) and tended (P < 0.06) to improve blastoocyst yield from oocytes (21.8 ± 1.1 v. 25.3 ± 1.1%). The objective of Exp. 2 was to evaluate whether blastocyst yield and survival after cryopreservation would be enhanced by BSA and hyaluronan. Embryos produced in vitro were cultured in 5% oxygen using a static system of modified SOF with or without 4 mg mL&#8211;1 BSA and with 0, 0.1, 0.5, or 1 mg mL&#8211;1 hyaluronan. Blastocyst and expanded blastocyst stage embryos on day 7 were vitrified (Campos-Chillon LF et al. 2006 Theriogenology 65, 1200&#8211;1214). Vitrified embryos were thawed and then cultured for 72 h in modified SOF containing 10% (v/v) fetal bovine serum and 50 &#181;m dithiothreitol. Re-expansion rate was recorded at 24 and 48 h, and the proportion of embryos that hatched by 72 h of culture was recorded. There was no effect of BSA or hyaluronan on cleavage rate. Blastocyst yield from oocytes was increased (P  < 0.0005) by BSA (15.3 ± 1.1 v. 20.9 ± 1.1%). Addition of hyaluronan at 1 mg mL&#8211;1 improved (P  < 0.04) blastocyst yield (16.2 ± 1.7 v. 21.2 ± 1.7%), but there was no effect at lower concentrations. There were no interactions between BSA and hyaluronan. Re-expansion rate at 24 and 48 h after thawing was reduced (P  < 0.007) by BSA (24 h: 39.1 ± 3.6 v. 17.0 ± 3.6%; 48 h: 45.6 ± 3.8 v. 18.7 ± 3.7%), and BSA tended (P  < 0.06) to reduce hatching rate at 72 h (22.3 ± 3.0 v. 9.8 ± 3.0%). Treatment of embryos with hyaluronan did not affect re-expansion rate at 24 h but tended (P  < 0.08) to increase re-expansion at 48 h. Moreover, hyaluronan increased (P  < 0.05) hatching rate at 72 h after thawing (0 mg mL&#8211;1  &#8211; 9.8 ± 4.2; 0.1 mg mL&#8211;1  &#8211; 16.9 ± 4.5; 0.5 mg mL&#8211;1  &#8211; 23.4 ± 4.1; 1.0 mg mL&#8211;1  &#8211; 14.2 ± 4.1%). In conclusion, blastocyst yield was improved by addition of fructose, BSA, and hyaluronan to culture medium and by use of a static culture system. Hyaluronan also enhanced cryosurvival, but BSA was detrimental to blastocyst survival after vitrification. Support: USDA NRI 2006-55203-17390, BARD US-3551-04. 
