title: Transcervical collection of bovine embryos up to Day 21: an 8-year overview.
abstract: Transcervical embryo collection is used routinely in the bovine species throughout the world to collect Day 6 to Day 9 embryos (early embryos) for genetic selection. For research purposes, however, the collection of embryos at later stages of pregnancy, i.e., Days 12 to 21 (late embryos), is needed. So far, for the recovery of late embryos, females are euthanized and embryo collection is performed after recovery of the genital tract. To reduce the number of animals used and still provide valuable material for embryo research, we have therefore developed a transcervical technique to collect late embryos. The objective of this study was to compare embryo recovery results at early and late stages within our laboratory. Altogether, 232 cows were used for this study. One hundred forty-five flushes were performed to collect embryos from Days 6 to 9, and 251 flushes were performed to collect embryos from Days 12 to 21. For the early embryos, a classical three-way collection equipment was used. To collect the late embryos, the same equipment was used, but the extensible flexible catheter that goes inside the external rigid catheter was removed, so that larger embryos could be collected through the remaining larger hole (two-way collection). All females were submitted to ovum pick up to remove the dominant follicle and were subsequently superovulated with FSH. Luteolysis was induced 48 hours before artificial insemination. Two artificial inseminations were performed with frozen semen, 48 and 56 hours after PGF2α injection. Before embryo collection, cows were treated with an epidural injection of a local anesthetic drug. The presence of CL was checked, and they were counted by rectal palpation. For all collections, the cervix was prepared with the initial introduction of a dilator. Then, the catheter was introduced in one horn, and the cuff was inflated as low as possible. For the collection of late embryos, the flushing solution (30 mL) was injected slowly twice to suspend the embryos before flushing the horn with 500 mL, and the same operation was performed on the second horn. There was no significant difference in the number of embryos collected per flush in the early- and late-stage (758 embryos collected, 5.22 ± 6.02 per flush vs. 1238 embryos collected, 4.93 ± 5.07 per flush, respectively). The number of embryos collected per CL, however, was significantly lower in the early versus late group (0.39 ± 0.32% vs. 0.44 ± 0.34%, respectively). The late collection allowed the retrieval of full conceptuses (embryonic and extraembryonic tissues), even at very late stages such as Days 18 to 21. Careful collection is needed, however, so that conceptuses are not damaged or torn: the horn must be massaged gently and the flush should be ideally recovered in one single flow. This technique is a powerful tool to collect the late-stage embryos for research purposes. Because it is not traumatic, animals can be used again for the same procedure.
authors: INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy-en-Josas, France; ENVA, UMR 1198 Biologie du Développement et Reproduction, Maisons-Alfort, France. Electronic address: christophe.richard@jouy.inra.fr.
authors: C
authors: C
authors: Richard
authors: INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy-en-Josas, France; ENVA, UMR 1198 Biologie du Développement et Reproduction, Maisons-Alfort, France.
authors: I
authors: I
authors: Hue
authors: INRA, UCEA Bressonvilliers, Leudeville, France.
authors: V
authors: V
authors: Gelin
authors: INRA, UCEA Bressonvilliers, Leudeville, France.
authors: A
authors: A
authors: Neveux
authors: INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy-en-Josas, France.
authors: E
authors: E
authors: Campion
authors: INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy-en-Josas, France; INSERM, UMR-S1139767, Faculté des Sciences Pharmaceutiques et Biologiques, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
authors: S A
authors: SA
authors: Degrelle
authors: INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy-en-Josas, France.
authors: Y
authors: Y
authors: Heyman
authors: INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy-en-Josas, France; ENVA, UMR 1198 Biologie du Développement et Reproduction, Maisons-Alfort, France.
authors: P
authors: P
authors: Chavatte-Palmer
mesh_terms: D000818:Animals; D002417:Cattle / Q000196:embryology*; D004622:Embryo, Mammalian; D047108:Embryonic Development / Q000502:physiology; D004777:Environment; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage; D005865:Gestational Age; D007315:Insemination, Artificial / Q000662:veterinary; D010062:Ovulation Induction / Q000662:veterinary; D011247:Pregnancy; D012099:Reproductive Techniques; D012106:Research; D013480:Superovulation; D020858:Tissue and Organ Harvesting / Q000379:methods / Q000662:veterinary*
chemical_list: D005640:Follicle Stimulating Hormone
keywords: Blastocyst; Cattle; Conceptus; Developmental stage; Elongation; Embryo; Superovulation