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Ovine tubal (n = 87) and ovarian in vitro matured oocytes (n = 99) were fertilized in vitro with ejaculated spermatozoa capacitated for 8 h in modified defined medium buffered with Hepes. High levels of fertilization were obtained as assessed by development to two- to six-cell stage within 40 h (75.8% for ovulated and 62.6% for in vitro matured oocytes). Electron microscope analysis of oocytes 20-22 h after insemination indicated that in vitro fertilization approximated the in vivo events. Embryos (two- to six-cell) were transferred surgically to the oviducts of pseudopregnant rabbits. Three days later, 42 (from ovulated oocytes) and 15 (from in vitro matured oocytes) embryos were recovered; 26 (61.9%) and 10 (66.6%), respectively, had cleaved at least once. Embryos incubated in vivo (n = 20 from ovulated oocytes; n = 9 from in vitro matured oocytes) were transferred surgically to the uteri of seven and four recipient ewes resulting in four and two pregnancies, respectively, from which three and one, respectively, have been maintained (greater than 3 months). The first lamb resulting from the in vitro fertilization of an ovulated oocyte was born. In addition, six embryos (two- to four-cell) from tubal oocytes and ten embryos (two- to six-cell) from in vitro matured oocytes were directly transferred to the oviducts of two and three ewes, respectively. Two pregnancies resulting from in vitro matured fertilized oocytes are in progress (greater than 3 months).

Summary. Repeated superovulation using three treatments of pFSH at intervals of 45 to 55 days during the same breeding season was carried out in 18 Prdalpes ewes.The embryos were recovered by surgery after the first two treatments and by slaughter after the last one at Day 6. Three lots of control ewes In = 5 or 6) receiving the same superovulation treatment were slaughtered respectively at the same time.The first and third repeated superovulation treatments gave averages of 5.2 + 0.6 and 4.5 ± 0.6 corpora lutea. The second one gave 3.4 t 0.4 corpora lutea, which was significantly lower than with treatments 1 and 3, but adhesions did not permit a perfect view of the whole surface of the ovaries. Introduction.

When different ages of juvenile allis shad Alosa alosa (18-74 days post-fertilization) were exposed for 48 h to elevated salinity (25 or 30), all ages could tolerate moderates salinity (25) whereas only the older stages could tolerate the higher salinity. In 88 days post-fertilization allis shad, acclimatation to full-strength sea water for 2 weeks did not lead to significant changes in total water content and gill Na þ /K þ -ATPase activity whereas total Na þ content increased within 5 days to values which remained stable thereafter. Together, these data suggest that juvenile allis shad develop a limited euryhalinity, which allows them to fully adapt to hyperosmotic environment immediately after transfer. # 2007 The Fisheries Society of the British Isles

Summary. The prolificacy of two rabbit strains (Californian and New Zealand) has been studied in parallel with ovulation rate and embryonic development. The number of mean ovulations was 11.6 in Californians and only 9.6 in New Zealands. In spite of the higher rate in the former, the number of young born was about 8 in both strains. Introduction.