Hostname: page-component-5d59c44645-ndqjc Total loading time: 0 Render date: 2024-02-24T04:15:42.506Z Has data issue: false hasContentIssue false

The role of structural integrity of the fertilising spermatozoon in early human embryogenesis

Published online by Cambridge University Press:  01 May 1999

Liliana T. Colombero
Affiliation:
The Center for Reproductive Medicine and Infertility, Department of Obstetrics & Gynecology, New York Presbyterian Hospital-Weill Medical College of Cornell University, New York, USA.
Maureen Moomjy
Affiliation:
The Center for Reproductive Medicine and Infertility, Department of Obstetrics & Gynecology, New York Presbyterian Hospital-Weill Medical College of Cornell University, New York, USA.
E. Scott Sills
Affiliation:
The Center for Reproductive Medicine and Infertility, Department of Obstetrics & Gynecology, New York Presbyterian Hospital-Weill Medical College of Cornell University, New York, USA. The Atlanta Reproductive Health Centre, Atlanta, Georgia, USA.
Zev Rosenwaks
Affiliation:
The Center for Reproductive Medicine and Infertility, Department of Obstetrics & Gynecology, New York Presbyterian Hospital-Weill Medical College of Cornell University, New York, USA.
Gianpiero D. Palermo
Affiliation:
The Center for Reproductive Medicine and Infertility, Department of Obstetrics & Gynecology, New York Presbyterian Hospital-Weill Medical College of Cornell University, New York, USA.

Abstract

While the fertilising spermatozoon supplies the active centre directing the human zygote's first mitotic division, the relative contributions of the sperm head and tail (as well as the importance of the sperm's general structural integrity) to subsequent developmental processes remain incompletely studied. The sperm nucleus contains paternal chromatin necessary for restoration of a diploid genome, but the functional role of the sperm tail (either attached or dissected) in early human embryonic growth is not known. In this investigation using oocytes donated by in vitro fertilisation patients, human oocytes were injected with isolated sperm heads (n = 73), isolated sperm flagella (n = 11) or both (dissected sperm heads + free sperm tails, n = 26). The formation of bipronucleate zygotes was recorded for each method. Among oocytes surviving injection with isolated sperm heads, 44 of 66 (67%) formed two pronuclei. Of oocytes receiving only sperm tails, 2 of 11 (18%) displayed two pronuclei, but a single polar body was evident in both cases. When dissected spermatozoa parts (head + tail) were jointly injected, 12 of 26 (46%) developed two pronuclei. From embryos resulting from each of these three fertilisation regimes, blastomere biopsies were obtained and subjected to multiprobe fluorescent in situ hybridisation (FISH) analysis to detect mosaicism or aneuploidy arising from these experimental treatments. Only embryos with growth sufficient to permit sampling of at least two blastomeres were evaluated, and FISH analysis was successful in 25 of 29 (86%) embryos tested. Of 12 embryos derived from injection of an isolated sperm head, only one was normal diploid; the remaining 11 were mosaic. Both embryos resulting from injection of an unattached sperm tail were mosaic. Of 11 embryos generated from oocyte injection with sperm head + tail segments, 10 (91%) were mosaic and only one was normal diploid. Results from this study show that injection of isolated sperm segments can permit oocyte activation and bipronuclear formation. However, a high rate of mosaicism in human embryos originating from disrupted sperm or sperm components suggests that more than a ‘sum of parts’ is needed for later development. The structural integrity of the intact fertilising spermatozoon appears to contribute to normal human early embryogenesis.

Type
Research Article
Copyright
1999 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)