Post‐hatching development of in vitro bovine embryos from day 7 to 14 in vivo versus in vitro

Abstract

This study evaluates the post-hatching development of in vitro-produced (IVP) embryos until Day 14. On Day 7, IVP embryos were either transferred to recipient uteruses or placed in a post-hatching development (PHD) system. As a control group, in vivo-produced (IVV), Day-7 embryos were also transferred to recipient uteruses. All groups were collected on Day 14 and were morphologically evaluated. Day-7 and Day-14 IVV and IVP embryos were used for quantification of eight genes (PLAC8, CD9, SLC2A1, SLC2A3, KRT8, SOD2, HSP1A1, and IFNT2) by reverse transcriptase qPCR. Day-14 embryos from the PHD system were smaller (2.92 ± 0.45 mm) and had a lower embryonic disk diameter (0.14 ± 0.00 mm) than those produced by IVV (24.18 ± 3.71; 0.29 ± 0.03 mm, respectively) or IVP (19.06 ± 2.43; 0.28 ± 0.01 mm) culture and transferred to the uterus (P > 0.05). Day-7 IVP embryos had a higher expression of the HSP1A1, SCL2A1, and SCL2A3 genes than IVV embryos. When these embryos were cultured in the uterus, no differences in gene expression were observed on Day 14. Conversely, Day-14 IVP embryos cultured in the PHD system showed a higher expression of PLAC8, SOD2, and SLC2A3 genes. It is concluded that Day-7 IVP embryos are different from IVV embryos in regards to gene expression, although exposure to the uterine environment during the elongation period allowed the IVP embryos to overcome this difference. In contrast, IVP embryos cultured in the PHD system were morphologically and molecularly different, being of poorer quality than those cultured in the uterus.

Embryo splitting affects the transcriptome during elongation stage of in vitro–produced bovine blastocysts

“…Nevertheless, there was a trend for the split embryos to be smaller than controls; elongated embryos derived from split blastocysts were in average smaller than 100-mm length. This is in agreement with others who also found variations in embryo size and recovery after distinct manipulation procedures [18,19,23,50,51] and with our own previous data [12] and those of Betsha et al, 2013 [50] on recovery and morphometry of cloned and IVP bovine embryos. Both groups confirmed that cloned elongated embryos were shorter than controls.…”

“…The bovine embryo in vivo develops further to the elongation stage where a new set of complex changes occur and the elongating conceptus gets in close communication with the uterine epithelium, to complete the implantation and the establishment of the pregnancy [18]. In this period also occurs the largest number of pregnancy losses, before the maternofetal recognition [2,[19][20][21][22].…”

“…An alternative option is to assess blastocyst development after transfer and recovering these embryos on Days 14 to 17 of development [13,19,21,23]. Elongated embryo provides important information of embryonic loss and can be used as a research model to evaluate the intrinsic quality of IVP embryos [18].…”

Expression of placenta-specific 8 in human oocytes, embryos, and models of in vitro implantation

“…PLAC8 expression has been reported in many species, such as zebrafish (3), mice (1), bovines (4)(5)(6)(7)(8)(9), and rabbits (16). However, little is known regarding PLAC8 expression in human oocytes and embryos.…”

“…These findings suggest that PLAC8 plays a crucial role in normal embryo development (3). In the evaluation of bovine embryo quality, PLAC8 is a biomarker that is used to predict pregnancy outcome (4)(5)(6)(7)(8)(9). Two recent reports investigated bovine embryos derived in vitro (4) and in vivo (10), and they demonstrated that PLAC8 was highly expressed in cells from embryos that were capable of developing into calves.…”