Simple separation of good quality bovine oocytes using a microfluidic device

Abstract

We fabricated a simple microfluidic device for separation of bovine oocytes based on the oocyte quality to improve the conception rate of in vitro fertilization (IVF) by using good quality oocytes. The microfluidic device separates oocytes based on sedimentation rate differences in a sucrose buffer, which is dependent on oocyte quality. The microfluidic device has a 700 µm width, 1 mm height, and 10 mm long separation channel. Oocytes were injected from the upper half of the separation channel, and they flowed while sinking. The outlets of the separation channel were divided into upper and lower chambers. Good quality oocytes settled faster than poor quality oocytes in sucrose buffer; therefore, good quality oocytes were collected from the lower outlet. We performed IVF after the microfluidic separation of oocytes. The developmental rate to blastocysts of oocytes collected from the lower outlet was significantly higher than those collected from the upper outlet (36.0% vs. 14.1%). This result was comparable to that in the BCB staining method performed as a comparison method (BCB+ : 35.7%, BCB−: 15.4%). These findings indicate that our microfluidic device could be applied to oocyte separation and contribute to improvement of in vitro embryo production system.

The incompletely fulfilled promise of embryo transfer in cattle—why aren’t pregnancy rates greater and what can we do about it?

“…One technology that has seen implementation in the field of assisted reproduction is microfluidics, for both IVP of embryos and cryopreservation ( Zhao and Fu, 2017 ; Weng, 2019 ). In cattle, microfluidic devices have been developed for sorting more viable sperm ( Li et al, 2016 ) and oocytes ( Iwasaki et al, 2018 ). A microfluidic apparatus containing bovine oviductal epithelial cells that is illustrated in Figure 7 has been used to support fertilization and embryonic development through day 4 of development ( Ferraz et al, 2018 ).…”

Microfluidics Era in Chemistry Field: A Review

“…By using a similar technique, a simple separation of submillimeter-sized particles reach 90, 90, 85, 65 and 55% degree of separation for 20, 30, 60, 90 and 150 L min -1 flow rate, respectively [18]. On the other hand, a simple separation of bovine oocytes has been performed within seconds, which is remarkable for biochemistry field [19].…”

In vitro embryos production of oocytes selected based on follicular size and by brilliant cresyl blue staining

“…Thus, morphological assessment only considers the indirect features of oocyte quality, such as cytoplasmic homogeneity, and the amount and quality of somatic cells in the cumulus-oocyte complex (BAKRI et al, 2016). Although this approach is widely used, it is quite subjective and its accuracy is limited, because some oocytes with normal morphology might be in an early stage of degeneration, leading to heterogeneous results (IWASAKI et al, 2018). Besides morphological evaluation of the oocytes, follicular characteristics have been used as well to improve IVP (DE BEM et al, 2014;IWASAKI et al, 2018).…”

“…Although this approach is widely used, it is quite subjective and its accuracy is limited, because some oocytes with normal morphology might be in an early stage of degeneration, leading to heterogeneous results (IWASAKI et al, 2018). Besides morphological evaluation of the oocytes, follicular characteristics have been used as well to improve IVP (DE BEM et al, 2014;IWASAKI et al, 2018). A previous study assessed the competence of bovine oocytes from varying follicles sizes and demonstrated that large follicles increased oocyte quality and blastocyst production, as compared to medium and small follicles (LABRECQUE et al, 2016).…”

“…This makes it possible to differentiate between different developmental phases of oocytes, as the BCB dye is metabolized and reduced to a less intense color by G6PDH (BRAGANCA et al, 2018;SU et al, 2012). Thus, blue staining of the oocyte cytoplasm indicates low specific activity of G6PDH (classified as BCB+), and is indicative of more competent oocytes (IWASAKI et al, 2018).…”