No abstract

No abstract

Porcine follicle stimulating hormone (pFSH) and porcine luteinizing hormone (pLH), are widely used to induce superovulation in cows. An advantage of this treatment is that the LH:FSH ratio can be varied to optimize the growth of the ovarian follicles. However, due to the relatively short half-life of FSH, the superovulatory treatment requires numerous injections. A performant radioimmunoassay system (sensitivity=0.2 ng/ml plasma) was used to determine plasma pFSH levels in cows that were superovulated with 2 daily injections of 4 Armour Units (A.U.) of pFSH for 4 d. From plasma profiles, the half-life and the disappearance of pFSH were estimated at 5 h and at 10 to 12 h, respectively, confirming the necessity of using two daily injections.

Mature mouse oocytes were exposed prior to in vitro fertilization to visible light during 1, 2, or 4 hr at an intensity of 4,000 lux. Compared to controls cultured under identical conditions but protected from light, exposed eggs did not show any significant modification of cleavage speed and rate. After transfer of blastocysts obtained in vitro in uteri of pseudopregnant females, the implantation rate and the proportion of normal fetuses were not found to be different in relation to preliminary light exposure of oocytes fertilized and cultured in vitro.

The survival after transfer of frozen\p=n-\thawedmouse blastocysts obtained from culture of in-vitro fertilized oocytes or 1-and 2-cell ova was compared. About 10% of transferred embryos developed to term in each group and there was no difference between embryos fertilized in vitro or in vivo. In addition to embryonic loss due to transfer, in-vitro cultivation and freezing reduced the proportion of fetuses considered viable at Day 15 of pregnancy (29\m=.\8 versus 50\m=.\7% and 26\m=.\3versus 50\m=.\7%respectively). When used together these procedures had an additive effect on fetal wastage (18\m=.\4 versus 50\m=.\7%). In-vitro culture also entailed a significant increase of resorbing implantation sites (10\m=.\2 versus 4\m=.3%). The re-expansion rate after freezing and thawing of blastocysts grown in vitro was paradoxically greater than that of blastocysts grown in vivo (85\m=.\8 versus 54\m=.\6%).