Development of a laparoscope-assisted method for oocyte collection from mature and prepubertal ewes

This thesis describes the development of a protocol for collecting oocytes from live mature ewes and prepubertal lambs. The procedure developed was a laparoscope-assisted surgical technique whereby the ovaries were located and elevated to a small midline incision and exteriorized for follicular aspiration. An assessment of this procedure as an efficient means of collecting oocytes of adequate quantity and quality while providing a humane, repeatable means of aspirating follicles with minimal effects on the health and future fertility of donors was conducted. The average number of oocytes collected from mature ewes was 8.5 +/- 0.62. This does not provide adequate potential for embryo production to justify use of this technique over traditional embryo transfer except in cases where superovulation and embryo collection cannot be used due to donor health problem or adhesions of the reproductive tract following multiple embryo collections. The technique enabled the efficient recovery of large numbers of oocytes from prepubertal lambs at 6 to 18 weeks of age when traditional embryo transfer is not possible. Average numbers of oocytes from unstimulated donor lambs were 31.8 +/- 7.3 at 6 weeks, 30.0 +/- 6.8 and 17.1 +/- 2.6 for two groups of 10-week-old lambs, 12.6 +/- 5.9 and 7.8 +/- 1.4 for two groups of 14-week-old lambs and 6.1 +/- 0.9 for 18-week-old lambs. Trials were conducted to determine the value of several hormone stimulation protocols for lambs for improving oocyte recovery and in vitro maturation and no benefit of hormone treatment was found. The technique was shown to be repeatable. It allowed the collection of consistent oocyte numbers at subsequent aspirations, had a lack of detrimental effects on donors' future fertility as demonstrated through breeding trials in which a 100% pregnancy rate was achieved, and created only minor ovarian lesions that were for the most part unlikely to interfere with future ovulations as judged by evaluation of repeatedly aspirated ovaries at necropsy and by histological examination.