Quality and Age of Companion Felid Embryos Modulate Enhanced Development by Group Culture1

Abstract

For some species, embryos cultured with conspecific companions may have enhanced in vitro development compared with singletons. The objective of this study was to determine the effect of quality and age of companion embryos on single felid embryos produced by in vitro maturation or in vitro fertilization. Test oocytes (intermediate quality) were inseminated and incubated alone or with 10 embryos derived from oocytes with a high, intermediate, or low glucose uptake. The effect of relative age of companion embryos on test embryo development was also examined by insemination and incubation of test oocytes alone or with 10 conspecific embryos that were older, younger, or the same age. Test embryos coincubated with better- or equal-quality companions had better development and more cells per embryo (mean +/- SEM number, 74.9 +/- 16.9 and 40.6 +/- 8.8, respectively, Day 7; P < 0.05) than test embryos coincubated with lesser-quality companions (5.1 +/- 1.4) or alone (8.4 +/- 3.7). Intermediate-quality embryos incubated with older companions had more cells per embryo (88.3 +/- 17.0; P < 0.01) than those incubated with synchronous (49.3 +/- 12.1) or younger (29.4 +/- 6.1) embryos. The cell number of solitary embryos (9.8 +/- 3.1) was less (P < 0.05) than that of every group of test embryos incubated with companions, regardless of age. In vitro development of solitary cat embryos is improved by culture with excellent-quality conspecific companions, particularly companions of an advanced age.

Improved felid embryo development by group culture is maintained with heterospecific companions

“…Singleton 'test' cat embryos benefited from group culture with better versus poorer quality conspecific companion embryos [55]. Thus, we suspect that some of the diversity in earlier published results about the value of group culture could be explained on the basis of companion embryo quality.…”

“…Post-pubertal domestic cat ovaries were recovered after ovariohysterectomy from local veterinary clinics throughout the most reproductively active periods of the year [53,55], from November through January (Study I) and January through April (Study II). During transport, ovarian pairs were stored in Dulbecco's phosphate buffered saline (D-PBS, #D1283; pH 7.4, containing 100 lU/ml penicillin and 100 mg/ml streptomycin) at 4 °C using ice-packs and paper padding.…”

“…were indicated to be intermediate quality and were chosen as 'test' embryos for all treatments [55]. Intermediate embryos were chosen as test embryos to allow greatest latitude in demonstrating a beneficial or detrimental effect of incubation with companions.…”

“…Metabolic selection of individual companion embryos is labor intensive and may not be available at the site of gamete rescue. As oocyte metabolism is linked to overall developmental potential [53,54], including time to first cleavage [55], we suggest that selection of high quality cat embryos can also be performed by assessing time to first cleavage as in cattle [56] and humans [57].…”

Microwells support high-resolution time-lapse imaging and development of preimplanted mouse embryos

“…14 For instance, a microfluidic device mimicking the in vivo fertilization and reducing polyspermy has been developed and commercialized. 15 Dynamic culture systems have been developed to recapitulate the in vivo embryo growth environment, to activate potential beneficial signaling pathways, and to disrupt gradients of molecules, such as factors released from degenerating embryos, 16 ions, 17 oxygen, 18 nutrients, 19 and waste products, 20 built up around embryos. 21 Here, we report the use of microwells for culturing early mouse embryos as schematically shown in Figure 1.…”