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M.V.Z. Marco A. Asprón Pelayo
E. P. López-DamiánA, T. FiordelisioA, M. A. LammogliaB, M. AlarcónB, M. AsprónC and C. S. GalinaA
A Universidad Nacional Autónoma de México, Mexico City, Mexico; B Universidad Veracruzana, Tuxpan, México;
C Universidad Autónoma de Querétaro, Querétaro, México
Reproduction, Fertility and Development 25(1) 226-226 http://dx.doi.org/10.1071/RDv25n1Ab155
Published: 4 December 2012
Abstract
Accurate evaluation of bovine embryos for assessing developmental stage and quality is critical to the success of any embryo transfer program. However, this evaluation process has been reported to be highly subjective in Bos indicus (BI) and can vary as much as 23% compared with that of Bos taurus (BT). These differences in assessment may be related to the quantity of lipid droplets (LD) within the embryo, which has been shown to have a negative effect in cryopreserving embryos. The aim of the present study was to characterize the number and size of LD in differentdevelopmental stages of fresh embryos from BI and BT and to compare LD across the three different embryo qualitygrades (1 = excellent or good, 2 = fair, and 3 = poor). Nonsurgical embryo collection was performed 7 days postinsemination in 10 BI and 10 BT females. Forty-eight embryos were evaluated for stage and grade using stereoscopicmicroscopy, processed for transmission electron microscopy, and stained with Nile red. Digitalized images were analyzed with ImageJ (National Institutes of Health, Bethesda, MD, USA), contour of lipid droplets were designed, and values of perimeter, area, and fluorescence intensity were assessed. Nonparametric statistical analysis (Mann–Whitney) was utilized. There was no difference in LD number for BT or BI for morulae and blastocyst; however, BI morulae presented larger LD compared with blastocyst stage embryos (286 μm v. 223 μm; P < 0.05). Likewise, BITF cells had more LD compared with inner cell mass (ICM) cells (48 v. 36; P < 0.05). BT TF cells exhibited larger LDcompared with ICM cells (149 μm v. 128 μm; P < 0.05), while BI embryos exhibited a larger area of LD in the ICMcompared with the TF (591 μm v. 472 μm; P < 0.05). In all embryos, BI contained more lipid droplets than BT (78 v.49; P < 0.05). Across all quality grades (good, fair, and poor) there was no difference in the number of LD in BTembryos; however, BI grade-3 embryos presented more LD than grade-1 (36 v. 25). BT embryos LD were larger than BI LD (907 μm v. 625 μm; P < 0.05). Fluorescence images showed higher arbitrary units of fluorescence (auf) for LD in BI compared with BT embryos (386 auf v. 280 auf; P < 0.05). These results suggest that BI embryos contain moreand smaller LD than BT embryos and the LD described for BI embryo quality grade 1 are larger than those of qualitygrades 2 and 3, and even though the number of LD in morulae and blastocyst stage embryos are not different LD sizeis reduced as development occurs.
Research funding provided by UNAM-DGAPA-PAPIIT IN200810.