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Ovarian stimulation with equine chorionic gonadotropin (eCG) is largely used in animal reproductive technologies to provide a larger number of oocytes and embryos and to improve the reproductive outcome. However, the consequences of maternal treatment with eCG on embryo gene expression patterns are not widely studied. The aim of this work was to assess the ovarian response (preovulatory follicular population, oocyte maturation, ovulation rate, and serum steroid concentrations), the early embryo survival and gene expression patterns of a panel of quality-genes involved in glucose intake, oxidative stress, apoptosis, proliferation, implantation, and fetal growth in embryos of lactating rabbits treated with eCG. A total of 34 primiparous rabbit does (Oryctolagus cuniculus) were randomly distributed at Day 23 postpartum into a treatment group receiving a unique nonsuperovulatory dose (25 IU) of eCG (eCG group; N ¼ 17 does); or a control group without eCG treatment previously to artificial insemination (control group; N ¼ 17 does). After 48 hours, 8 does of each group were euthanized and their ovarian response was studied. The rest of animals were artificially inseminated and their ovulation was induced with a GnRH analogue. Embryos were recovered 3.5 days later. The oocytes retrieved for in vitro maturation showed no differences in metaphase II rate in both experimental groups, although oocyte cytoplasmic maturation, in terms of cortical granule migration rate, was improved in eCG-treated does (P < 0.05). The mean number of preovulatory follicles was similar between groups but the ovulation rate was significantly higher in eCG-treated does compared with does not stimulated (P < 0.05). No differences were found in serum estradiol and progesterone concentrations of does the day of oocyte and embryo recovery, respectively. However, progesterone:estradiol ratio was slightly increased in eCG group on embryo recovery day (P ¼ 0.1). The percentage of embryos recovered at the b, Depto. de Producción Animal, Fac. de Veterinaria, TRUE, pub

[EN] Contents In this study, lectin histochemistry was performed on paraffin sections to compare carbohydrate expression of oviductal isthmus and uterine endometrium in rabbits during early embryo development. Rabbit embryos are surrounded not only by the zona pellucida but also by tubal secretion-derived mucinous coat material, the mucin coat. Twenty sexually mature females were euthanized at 0 (pre-ovulatory group) and 24, 72 and 96h after insemination (pseudopregnancy group). The following lectin-binding agents were used: Arachis hypogaea, Peanut (PNA) to label galactosyl (-1,3)N- acetyl-galactosamine, Dolichos biflorus Agglutinin (DBA) to label galactosyl (-1,4)N- acetyl-galactosamine, Lens curinaris (LCA) to label --mannose, -d-glucose and Pisum sativum agglutinin (PSA) to label -d-mannose, -d-glucose. Blood was collected by cardiac puncture, and direct enzyme immunoassay technique was used to measure progesterone concentration. A significant increase in total plasma progesterone concentrations was detected at 96h post-ovulation when compared with 0, 24 and 72h post-ovulation (2.9 +/- 0.5 vs 0.5 +/- 0.15, 1.6 +/- 0.5 and 1.5 +/- 0.4ng/ml, at 96h vs 0, 24 and 72h post-ovulation, respectively). No differences between pre-ovulatory and pseudopregnant females were observed for glycoprotein localization in isthmus. In contrast, in the endometrium, differences in the glycoprotein detection between pre-ovulatory and pseudopregnant stages were detected. PNA to label galactosyl (-1,3)N- acetyl-galactosamine was not detected at the pre-ovulatory stage, but its presence was detected at 24h after ovulation. Both PSA and LCA to label -d-mannose, -d-glucose were only detected at 72h after ovulation. DBA detection was similar for all stages of the reproductive cycle. Therefore, N-acetyl-galactosamine secreted from isthmus could be involved in the formation of the embryonic mucin coat. d-galactose (PNA), d-glucose and d-mannose (PSA and LCA) might be crucial for the implantati