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Detailed analysis of cytoplasmic strings in human blastocysts: new insights

Published online by Cambridge University Press:  17 November 2022

Jessica Eastick Open the ORCID record for Jessica Eastick [Opens in a new window] ,
Christos Venetis ,
Simon Cooke  and
Michael Chapman
Jessica Eastick*
Affiliation:
IVFAustralia, New South Wales, Australia University of New South Wales, New South Wales, Australia
Christos Venetis
Affiliation:
IVFAustralia, New South Wales, Australia University of New South Wales, New South Wales, Australia
Simon Cooke
Affiliation:
IVFAustralia, New South Wales, Australia University of New South Wales, New South Wales, Australia
Michael Chapman
Affiliation:
IVFAustralia, New South Wales, Australia University of New South Wales, New South Wales, Australia
*
Author for correspondence: IVFAustralia PO Box 417 New Lambton, New South Wales, 2305 Australia. E-mail: Jessica.eastick@hunterivf.com.au
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Summary

The aim of this study was to determine if there was an association between the presence of cytoplasmic strings (CS) and their characteristics, with blastocyst quality, development and clinical outcome in human blastocysts. This two-centre cohort study was performed between July 2017 and September 2018 and involved a total of 1152 blastocysts from 225 patients undergoing in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). All embryos were cultured in Embryoscope+ and were assessed for CS using time-lapse images. A single assessor examined all blastocysts and reviewed videos using the EmbyroViewer® Software. Blastocyst quality was assessed on day 5 of embryo development. The number of CS, location and duration of their activity was recorded on days 5/6. A positive association between the presence of CS in human blastocysts with blastocyst quality was identified. Blastocysts with a higher number of CS present, were of higher quality and were in the more advanced stages of development. Top quality blastocysts had CS activity present for longer, as well as having a higher number of vesicles present travelling along the CS. Blastocysts that had CS present, had a significantly higher live birth rate. This study has confirmed that a higher number of CS and vesicles in human blastocysts is associated with top quality blastocysts and is not a negative predictor of development. They had a higher number of CS present that appeared earlier in development and, although ceased activity sooner, had a longer duration of activity. Blastocysts with CS had a significant increase in live birth rate.

Keywords

BlastocystCytoplasmic stringEmbryo developmentTime-lapseUltrastructure
Type
Research Article
Information
Zygote , Volume 31 , Issue 1 , February 2023 , pp. 78 - 84
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Copyright
© The Author(s), 2022. Published by Cambridge University Press

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