In vitro development of ovine embryos in CZB medium

Evidence that glucose is not always an inhibitor of mouse preimplantation development in vitro

A factorial experimental design was used to examine the effects of 16 combinations of four concentrations of glucose (0.20, 0.60, 1.8, 5.4 mmol/l) and four concentrations of potassium dihydrogen phosphate (KH(2)PO(4); 0.05, 0.15, 0.45, 1.35 mmol/l) on the development in vitro of outbred CF1 mouse zygotes. Three responses were measured: (i) the number of zona-enclosed blastocysts; (ii) the number of blastocysts that started to hatch; and (iii) the total cell counts in the blastocysts. General linear modelling was used to estimate the most parsimonious two-dimensional concentration-response surfaces that represent the three responses to the different concentrations of glucose and KH(2)PO(4). There were no significant interactions between the effects of glucose and KH(2)PO(4) in all cases. Thus, the effects of glucose and phosphate are independent. No significant effects of glucose on blastocyst formation and the initiation of hatching were observed. Increasing the concentration of KH(2)PO(4) inhibited slightly (</=20%) the development of zygotes into blastocysts and the initiation of hatching. The slight inhibitory effects of KH(2)PO(4) appeared to be due to the inhibition of the development of a few sensitive embryos. No significant effects of glucose and KH(2)PO(4) were observed on the total cell counts.

Current state in biotechnology in canine and feline reproduction

Biotechnology has proceeded much further in cats than in canines, although the pregnancy rate after in vitro maturation (IVM), IVC and embryo transfer (ET) is still relatively low. The use of AI with frozen-thawed semen as a breeding tool to overcome breeding incompatibility or to preserve male genetic material has been limited in felines in contrast to the situation in domestic dogs and foxes. In many research scenarios and endangered felid species programs, the in vitro production of feline embryos with subsequent transfer has complemented the use of AI. Improvement of IVM, in vitro fertilization (IVF) and embryo culture coupled with ovarian tissue grafting, cryobanking of follicles, oocytes, semen, or embryos, with subsequent ET into surrogate females, may render this technology feasible for use in endangered wild felids. In canines, reliable systems for in vitro production of embryos, embryo cryopreservation and transfer are yet to be developed. The refinement of invasive fertilization techniques, such as intracytoplasmic sperm injection (ICSI), may eventually provide a tool for removal of recipient oocyte nuclei and transfer of selected embryonic or somatic cell donor nuclei into domestic cat ooplasm, thereby providing a tool for genetic modification, or for preservation of valuable genetic material.