Sequential transformations of human sperm nucleus in human egg
In-vitro insemination of human zona-free oocytes prepared from oocytes that failed to fertilize in an in-vitro fertilization programme was used as an experimental model to study the time course and morphological events during the development of sperm nuclei into male pronuclei. At 30 min after insem...
Saved in:
Published in | Journal of reproduction & fertility Vol. 91; no. 2; pp. 393 - 402 |
---|---|
Main Authors | , |
Format | Journal Article |
Language | English |
Published |
England
Society for Reproduction and Fertility
01.03.1991
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | In-vitro insemination of human zona-free oocytes prepared from oocytes that failed to fertilize in an in-vitro fertilization
programme was used as an experimental model to study the time course and morphological events during the development of sperm
nuclei into male pronuclei. At 30 min after insemination, 22 eggs were cultured in a CO 2 incubator for further 3·5 h and 17 eggs were placed individually between a slide and coverslip for randomly repeated microscopical
observations in a controlled environment for at least 3·5 h. Simultaneous arrest of maternal meiosis and sperm nuclear development
occurred in 36·4% (8/22) eggs cultured in the CO 2 incubator and 47·1% (8/17) of those cultured between a slide and coverslip. Sequential transformation of the human sperm
nucleus in human eggs was studied in 6 eggs that showed continuous development of sperm nuclei into male pronuclei during
at least 3·5 h after insemination. The early sperm nuclear development in human egg ooplasm can be divided into three phases:
the sperm nucleus first decondenses (phase 1) then partly recondenses (phase 2) before expanding again to form an early male
pronucleus (phase 3). The prepronuclear stages (phases 1 and 2) took about 60 min each and the pronuclear formation (phase
3) began between 120 and 170 min after insemination. Early pronuclear formation was associated with the occurrence of dense
outline material, probably a precursor of the future pronuclear membrane, around the recondensed nucleus in re-expansion (phase
3). Between 30 and 60 min after the beginning of phase 3, numerous (> 20) dense grains, considered as nucleolar precursors,
were clearly visible inside the growing male pronucleus. Moreover, we have examined sperm nuclear changes in some eggs in
which the progression of late meiosis was abnormal. Meiotic arrest of maternal chromatin was always associated with arrest
of sperm head development. In 75% (6/8) of the eggs arrested in the metaphase II stages and in 87·5% (7/8) of the eggs arrested
in late anaphase II, sperm nuclear development was stopped at the decondensed and recondensed stages, respectively. We have
always observed male pronuclei when a maternal pronucleus was present in the egg. These observations suggested that maternal
chromatin and sperm nuclear development are probably regulated by common factor(s).
Keywords: man; egg; polyspermy; sperm nuclear development; pronuclear membrane; pronuclei formation |
---|---|
ISSN: | 1470-1626 0022-4251 1741-7899 |
DOI: | 10.1530/jrf.0.0910393 |