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Embryo development and embryo transfer in the European mink (Mustela lutreola), an endangered mustelid species.

The European mink is an endangered Mustelidae species and thus requires effective conservation measures, although little is known about reproduction in this species. In particular, preimplantation development has not been studied and, therefore, embryonic development and the growth of embryos was documented in the present study for European mink using light and fluorescent microscopy. Embryos develop in the oviducts and then migrate into the uterus on Day 6 post coitum (p.c.) at the morula stage. Embryos expanded as blastocysts from Day 7 until implantation on Day 12 p.c. Based on these findings, the use of embryo transfer for a conservation programme for the European mink was evaluated. Embryos were flushed from European mink resource females and transferred into the uterine horns of recipient hybrid females (honoriks and nohoriks). These hybrids were obtained by mating European polecat males with European mink females and vice versa. A total of 40 embryos was transferred and 20 live kits were born. The rates of pre- and postnatal survival were 50% and 70%, respectively. Both male and female offspring were lighter at birth in the embryo transfer group compared with naturally born controls, but there was no difference at 3 months of age.

Animals↗

Porcine sperm factor supports activation and development of bovine nuclear transfer embryos.

A study was undertaken to determine whether injection of porcine sperm factors (pSF), which trigger oscillations in intracellular calcium concentration ([Ca(2+)](i)) in mammalian oocytes, could be used to activate bovine oocytes during nuclear transfer. To date, only combined treatments that induce a monotonic rise in [Ca(2+)](i) and inhibit either phosphorylation or protein synthesis have been utilized in nuclear transfer. Several doses of pSF were tested. Injection of 5 mg/ml pSF triggered [Ca(2+)](i) oscillations that resembled those associated with fertilization with respect to amplitude and periodicity, and as a result, a high percentage of oocytes underwent activation. Furthermore, this concentration of pSF supported in vitro and in vivo development up to 60-90 days of gestation, comparable to development in control nuclear transfer embryos. Nevertheless, neither activation procedure supported development as well as did fertilization. The effectiveness of pSF as an activating agent in bovine oocytes may have been compromised because pSF was unable to support oscillations past 3-5 h postinjection and a second injection was necessary to extend the [Ca(2+)](i) oscillations. Likewise, a single injection of pSF failed to trigger downregulation of the inositol 1,4,5-trisphosphate receptor 1 subtype, whereas a second injection downregulated the receptor in a manner similar to that seen in fertilized oocytes. These results demonstrate that soluble factor(s) from porcine sperm can support early development in bovine nuclear transfer embryos; however, the efficacy may be limited because of the premature cessation of the induced oscillations.

Animals↗

Clinical outcome of day 2 versus day 3 embryo transfer using serum-free culture media: a prospective randomized study.

PURPOSE: The objective was to evaluate whether extending the embryo culture period from 2 to 3 days would yield a more optimal selection of viable embryos, thereby increasing the implantation and live birth rates. METHODS: Patients undergoing in vitro fertilization with at least one oocyte fertilized were prospectively randomized to 2 or 3 days of embryo culture in serum-free media. On the basis of their morphology and cleavage rate, a maximum of three embryos was selected for transfer. RESULTS: Embryos transferred on day 2 or day 3 were similar morphologically, however, a higher proportion of retarded embryos was observed on day 3. The implantation rate was 15.8 and 14.3% for day 2 and day 3 transfers, respectively. The increase in live birth rate from 18.5 to 22.6%, possibly suggesting a better embryo selection on day 3, was not statistically significant. CONCLUSIONS: Extending the embryo culture period from 2 to 3 days had no effect on implantation and live birth rates.

Birth Rate↗

Ultrasonographic monitoring of 103 recipient mares of different reproductive status during the first 30 days after embryo transfers.

Ten pluriparous mares were used as donors to supply embryos which were transferred into 103 recipients, 31 of which were nulliparous, 34 were pluriparous and lactating, and 38 were pluriparous and non-lactating. The embryos were recovered eight days after ovulation and pregnancy was confirmed by ultrasound six days after the transfer; the length of the embryos was measured ultrasonographically on days 12, 14, 16, 18, 20, 25 and 30 after the embryo transfer. One hundred and fifteen of 200 flushes provided embryos, 12 being degenerate and 103 being viable embryos. From the 103 embryo transfers carried out, 51 pregnancies were confirmed by ultrasound within 30 days; 16 of the 31 nulliparous recipients became pregnant, 16 of the 34 pluriparous lactating recipients and 19 of the 38 pluriparous non-lactating recipients. There were no significant differences between the groups of mares in the mean (sd) rate of growth of their embryos between 12 and 30 days of gestation.

Animals↗

The technique for human embryo transfer.

In a program of human in vitro fertilization (IVF), the results of 204 attempted intracervical embryo transfers (ETs), using a variety of catheters in three trials over 18 months, have been analyzed for the ease of transfer and pregnancy rate. In nulliparous patients, transfers were more difficult than in multiparous patients; and a closed-end Teflon catheter was found to be more easily passed through the smaller cervical canal than an open-end catheter. The overall pregnancy rate was 17% (March 1980 to August 1981) and was not related to catheter type, although when chemical pregnancies were excluded, it was found that transfers using open-end catheters were more successful. The transfer procedure developed finally for routine use incorporates a consideration of these results.

Embryo Transfer↗

Bilateral tubal pregnancy following in vitro fertilization and embryo transfer.

We have presented a case of bilateral tubal pregnancy following in vitro fertilization and embryo transfer. The most likely cause, in our opinion, is 'spray effect' which was discussed. The diagnosis of ectopic pregnancy must always be kept in mind in IVF&ET program, due to its high incidence of occurrence compared to natural conception. Although the incidence of bilateral tubal pregnancy is not high, one should identify the opposite adnexa when tubal pregnancy is diagnosed in an IVF&ET patient. Early diagnosis is essential for prevention of significant maternal morbidity and mortality.

Adult↗