The SPOM-adapted IVM system improves in vitro production of bovine embryos.

This study aimed to test the effects of an IVM SPOM adaptation (SPOM-adapted IVM) on the production, total number of cells (TNC), apoptosis, and cryotolerance (post-warming survival and cytoskeleton actin integrity) of bovine IVP embryos. Two experiments were conducted with two experimental groups based on IVM treatment: A control group (TCM 199 without FCS) and an SPOM-adapted group (TCM 199 with forskolin and IBMX in pre-IVM and IVM with cilostamide). The first experiment evaluated embryo in vitro production, TNC, and apoptosis rate on D9 of development. In the second experiment, embryos were vitrified/warmed at D7 (control fresh and vitrified; SPOM-adapted fresh and vitrified) and assessed regarding post-warming survival rates and cytoskeleton actin integrity. Statistical analysis was performed using GraphPad INSTAT software at a significance level of 5%. An increase (p < 0.05) in blastocyst production was observed in the SPOM-adapted group comparing to the control group. There was no difference (p > 0.05) in the TNC or apoptosis rate between the groups. Regarding cryopreservation, no differences were found (p > 0.05) in actin integrity or post-warming survival rates between the vitrified groups. In both vitrified groups, we observed a significantly lower uninjured pattern of actin integrity compared to the fresh groups (p < 0.05). We conclude that the SPOM-adapted IVM system is beneficial for blastocyst production and does not affect the quality and cryotolerance of the produced embryos.

Oocyte origin affects the in vitro embryo production and development of Holstein (Bos taurus taurus) - Gyr (Bos taurus indicus) reciprocal cross embryos.

A reciprocal crossbred embryo production approach was used to assess effects of maternal breed on embryo development in tropical conditions (average temperature 22.0 °C and 77.9% relative humidity). Oocytes were recovered by ovum pick-up (OPU) from Gyr and Holstein donors (n = 90 Holstein and 83 Gyr OPUs). Female F1 embryos were produced by fertilization with sperm bearing X-chromosomes from Holstein semen (n = 615 Gyr oocytes) or Gyr semen (n = 255 Holstein oocytes). Blastocysts were transferred to recipients 168 h post-insemination (h.p.i.) (n = 70-144) and there were assessments of pregnancies until birth. Oocyte number per OPU (Gyr 10.0 ±â€¯0.7 compared with Holstein 6.3 ±â€¯0.4) and percentage viable oocytes (Gyr 78.8 ±â€¯1.9% compared with Holstein 71.2 ±â€¯2.2%) were less for Holstein donor animals. There was a 2.8 fold fewer total number of F1 blastocysts when Holstein donors were used (Gyr: 260, Holstein: 91). Pregnancy assessment during the different stages of gestation indicated the percentage pregnancy was less when embryos were produced from Holstein oocytes (Gyr and Holstein respectively: early pregnancy, 47.9% compared with 38.6%; mid-pregnancy, 44.4% compared with 31.4%; late pregnancy, 41.0% compared with 22.9%). Pregnancy length was also affected by maternal breed (Gyr: 280.8 ±â€¯0.6, Holstein: 286.3 ±â€¯0.7). It is concluded that in a tropical environment the maternal breed affects crossbred embryo development with pregnancy rates during the latter stages of gestation being greater when Gyr oocytes are used for production of embryos.

Post implantation development reveals that biopsy procedure can segregate "healthy" from "unhealthy" bovine embryos and prevent miscarriages.

Embryo biopsy has been performed in bovine in vivo produced embryos for the last twenty years, but little could be done with few embryonic cells in the past. Recently, advances in single cell analysis enabled a wide range of applications using embryo biopsy, from morphology to genetics analysis and different omics-techniques, which are promising for in vitro-fertilized (IVF) embryos. The aim of this study was to address if biopsy procedure would affect post implantation development of IVF blastocyts. Here we show that blastocyst stage do not affect re-expansion of biopsied embryos (regular blastocyst: 73.7%; expanded blastocyst: 73.1%), but affects (p<0.05) implantation (regular blastocyst: 37.8%, expanded blastocyst: 61.0%), so ideally biopsy should be performed in expanded blastocysts. No detrimental effect of biopsy procedure was detected for post-implantation development (calving rates, Biopsy: 47.1%, Control: 41.9%), and normal calves were born (Birth weight, Biopsy: 32.10±7.20kg; Control: 30.95±5.43kg). Surprisingly, we found interesting results suggesting embryo survival can be increased with aggressive procedures (such as embryo biopsy), and this is highly associated with early pregnancy loss (Biopsy: 0%, Control: 17.4%). This finding also suggests morphological classification of day 7 blastocysts is far from ideal, and supposedly, unhealthy embryos can implant but are bound to miscarriage during the first trimester (non-biopsied embryos). Our results show biopsy procedure is safe for bovine IVF embryos, and shed new light into the importance of conceptus in early pregnancy loss in cattle.