title: The effect of gamete co-incubation time during in vitro fertilization with frozen-thawed unsorted and sex-sorted ram spermatozoa on the development of in vitro matured adult and prepubertal ewe oocytes.
abstract: In vitro matured adult (Experiment 1) and prepubertal (Experiment 2) ewe oocytes were co-incubated with unsorted or sex-sorted frozen-thawed spermatozoa for 2 to 3 h (short) or 18 to 20 h (long) to determine the effects of reducing the gamete co-incubation time during IVF on subsequent embryonic development in vitro. For oocytes derived from adult ewes, there were no differences in oocyte fertilization and cleavage at 24 h post insemination (hpi) between types of spermatozoa or co-incubation times (P > 0.05). By 48 hpi, oocyte cleavage was higher after a short (390/602, 64.8%) compared with a long (381/617, 61.7%) co-incubation (P < 0.05), and was not significantly different for unsorted (266/372, 71.5%) and sex-sorted (505/849, 59.9%) spermatozoa. Blastocyst formation from cleaved oocytes was similar for unsorted (150/266, 56.4%) and sex-sorted (295/505, 58.4%) spermatozoa, but was higher after a short (240/390, 61.5%) than long (205/381, 53.8%) co-incubation (P < 0.05). Oocyte development to the blastocyst stage was not different for unsorted (150/372; 40.3%) and sex-sorted (295/847; 34.8%) spermatozoa but was significantly increased by a short (240/602, 39.9%) compared with a long (205/617, 33.2%) co-incubation. Fertilization of oocytes from prepubertal ewes was similar for types of spermatozoa and for duration of co-incubation. Oocyte cleavage (48 hpi) was similar for a short (241/377, 63.9%) and long (226/349, 64.8%) co-incubation with unsorted spermatozoa, but was increased (P < 0.05) by a long co-incubation (286/500, 57.2% versus 163/517, 31.5%) with sex-sorted spermatozoa. Blastocyst formation from cleaved oocytes was similar for unsorted (230/467, 49.3%) and sex-sorted (186/449, 41.4%) spermatozoa, and a short (200/404, 49.5%) or long (216/512, 42.1%) co-incubation. However, oocyte development to the blastocyst stage was higher (P < 0.05) after IVF with unsorted (230/726, 37.1%) than sex-sorted (186/1017, 18.3%) spermatozoa. Reducing the duration of gamete co-incubation did not deleteriously affect the in vitro development of adult and prepubertal ewe derived oocytes after IVF with unsorted and sex-sorted spermatozoa. In general, sex-sorting had no substantial influence on fertilization and embryo development rates.
authors.affiliation: Centre for Advanced Technologies in Animal Genetics and Reproduction (ReproGen), Faculty of Veterinary Science, The University of Sydney, NSW 2006, Australia. kmorton@vetsci.usyd.edu.au
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Morton
authors.forename: Sally L
authors.initials: SL
authors.lastname: Catt
authors.forename: Fiona K
authors.initials: FK
authors.lastname: Hollinshead
authors.forename: W M Chis
authors.initials: WM
authors.lastname: Maxwell
authors.forename: Gareth
authors.initials: G
authors.lastname: Evans
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology; D002469:Cell Separation / Q000662:veterinary; D002970:Cleavage Stage, Ovum; D015925:Cryopreservation / Q000662:veterinary; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods / Q000662:veterinary*; D005434:Flow Cytometry / Q000662:veterinary; D008297:Male; D009865:Oocytes / Q000502:physiology*; D012662:Semen Preservation / Q000662:veterinary*; D012732:Sex Determination Analysis / Q000662:veterinary*; D012756:Sheep / Q000502:physiology*; D013094:Spermatozoa / Q000166:cytology / Q000502:physiology*; D013997:Time Factors