Effects of recipient oocyte source, number of transferred embryos and season on somatic cell nuclear transfer efficiency in sheep

Abstract

To improve the efficiency of somatic cell nuclear transfer (SCNT) in sheep, we investigated the effects of recipient oocyte source, number of transferred embryos and season on the pregnancy and live lamb rates for sheep somatic cell nuclear transfer embryos. Follicle‐stimulating hormone (FSH)‐stimulated ovaries produced significantly more oocytes both in total and of suitable quality for maturation culture than those without FSH treatment (from slaughterhouse). However, their in vitro maturation rates were similar. Embryos were reconstructed using adult fibroblast cells into enucleated MII oocytes. The pregnancy and term rates were significantly higher in the FSH‐stimulated group than in the slaughterhouse one. Oocytes from FSH‐stimulated ovaries were enucleated as recipient cytoplasm for nuclear transfer in the following experiments. The transfer of 7–9 and 11–13 embryos produced significantly higher pregnancy rates than that of six embryos. However, the former groups exhibited similar live lamb rates. FSH‐stimulated ovaries produced significantly more oocytes in November and December (winter) than in May to July (summer), but the associated maturation rate did not increase. Pregnancy and term rates were significantly higher when transfer occurred in winter than in summer. In conclusion, FSH treatment produced significant benefit regarding the number and quality of collected oocytes and also for the pregnancy and live lamb rates for reconstructed embryos. However, the transfer of an appropriate number of embryos (7–13) and at an appropriate season (winter) increased pregnancy and term rates.

Development and pregnancy rates of Camelus dromedarius-cloned embryos derived from in vivo- and in vitro-matured oocytes

“…A r t i c l e development and producing offspring [4,6,[10][11][12][13]. However, studies on embryo development and pregnancy rate according to oocyte sources are limited in camels.…”

“…Studies on the pregnant efficiency to oocyte sources in camels reported so far have used a small number of oocytes and surrogates [4,6]. Furthermore, several studies on the efficiency of pregnancy have been reported that the in vitro matured oocytes showed decreased pregnancy rates in other mammalians, including sheep, mouse, and human [11][12][13]. Therefore, the present study used a large number of surrogates, slaughtered ovarieshouse-, and OPU-derived oocytes to reconfirm the effect of the source of oocytes on pregnant efficiency.…”

“…Oocyte maturation rates are additionally reported in the present study, information absent in the aforementioned previous reports; providing a more complete understanding of the capacity and limitation of oocyte sources.Furthermore, the number of oocytes and surrogates according to the oocyte sources showed a difference of about three [6] and eight times [4], and the efficiency of in vivo and in vitro maturation was also not analyzed [4,6]. Several studies have evaluated such similar strategies using different maturation system of oocytes with various kinds of mammals, including sheep, mouse, and human [11][12][13]. In the case of sheep, SCNT embryos were transferred to surrogates, and an in vivomatured oocyte group was determined to have high pregnancy and full-term development rates [13].…”

“…Several studies have evaluated such similar strategies using different maturation system of oocytes with various kinds of mammals, including sheep, mouse, and human [11][12][13]. In the case of sheep, SCNT embryos were transferred to surrogates, and an in vivomatured oocyte group was determined to have high pregnancy and full-term development rates [13].…”

Extranuclear Inheritance of Mitochondrial Genome and Epigenetic Reprogrammability of Chromosomal Telomeres in Somatic Cell Cloning of Mammals

“…(3) sheep [21][22][23][24][25][26]; (4) pigs [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]; (5) equids-domestic horses [42][43][44][45][46] and mules [47]; (6) water buffaloes-Chinese swamp buffaloes [48,49] and Indian river/riverine buffaloes [50][51][52][53]; (7) one-humped or dromedary camels [7,[54][55][56]; (8) two-humped or Bactrian camels [57]; (9) domestic cats [58][59][60][61][62][63]; (10) domestic dogs…”