TY - JOUR
AR - CROGR-2020-2-102
TI - A Noninvasive Method for Assessing Oocyte Competency
AU - Cara Wessels, Wells
AU - L. , Penrose
AU - M. , Orth
AU - S. , Prien
JO - Case Reports in Obstetrics Gynecology and Reproductive
PY - 2020
DA - Fri 03, Jul 2020
SN - 2674-5070
DO - http://dx.doi.org/10.31487/j.CROGR.2020.02.02
UR - https://www.sciencerepository.org/a-noninvasive-method-for-assessing-oocyte-competency_CROGR-2020-2-102 
KW -  Oocyte competency, oocyte viability, oocyte buoyancy, noninvasive, specific gravity device
AB - There is an increasing demand to evaluate oocyte competency and viability for oocyte cryopreservation and
use for in vitro fertilization. Oocytes suffer decreased survival of cryopreservation as compared to embryos,
due to physical characteristics of the oocyte. The objective of this study is to determine if a specific gravity
device (SGD) can estimate oocyte viability based on oocyte descent through the buoyancy system. All
experiments were performed in a research laboratory with a randomized block design with repeated
measures. Three hundred-seventy-six oocytes were collected from seven mice and randomly assigned to
one of four treatments: exposure to 60C for 30 min, acidified media for 1h, ethylene glycol-glycerol
cryoprotectant for 1h, or standard culture to serve as control. To further analyze the relationship between
oocyte descent time and viability, 98 additional oocytes were passed through SGD before and after
treatment. Oocytes were stained with Coomassie Blue to determine membrane permeability and estimate
viability based on treatment. Oocytes treated with 60C heat, acidified media and ethylene glycol/ glycerol
cryoprotectant solution demonstrated altered descent times from control and pre-treatment oocytes
(P<0.05). Oocytes exposed to heat and cryoprotectants descended more rapidly through SGD than control
and pre-treatment oocytes (P<0.05). Oocytes treated with acidified media descended more slowly through
SGD (P<0.05). Permeation of stain into oocytes exposed to lethal treatments confirmed changes in
membrane integrity post-treatment and further indicates SGD can detect such shifts. This suggests SGD can
predict competency between live and dead oocytes. In conclusion, SGD can detect shifts in oocyte density
due to altered membrane permeability, which can suggest information about oocyte competency. This
information can help differentiate between high- and low-quality fresh oocytes to help select which oocytes
to freeze and result in improved oocyte cryopreservation and fertilization.