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High rate of premature chromosome condensation in human oocytes following microinjection with round-headed sperm: case report.

Authors
Type
Published Article
Journal
Human reproduction (Oxford, England)
Publication Date
Volume
20
Issue
5
Pages
1319–1323
Identifiers
PMID: 15760963
Source
Medline

Abstract

A young couple proceeded to three ICSI treatment cycles because of male infertility. The semen samples varied between 10 x 10(6) and 36 x 10(6)/ml, 38 and 51% progressive motility but 0% normal morphology. Different types of sperm heads, mostly round-headed with varying spherical appearance (86%) were presented beside acephalic sperm (pinheads; 12%), both one- or two-tailed and the former also without a tail. Very few sperm (2%) exhibited slightly oval-shaped heads. Electron microscopy revealed the absence of the acrosome combined with disturbance of the chromatin condensation among the round-headed sperm. In all three cycles, the fertilization rate using the round-headed sperm fraction was very low with the best result of 2/18 (11%) two-pronucleate oocytes and one one-pronucleate oocyte obtained in the second ICSI cycle. The three oocytes cleaved and were transferred in the 3-4-cell stage without achieving a pregnancy. Of the 29 unfertilized and prepared oocytes from the last two cycles, 27 were informative and revealed the maternal metaphase II chromosomes in the haploid range and a high rate (85%) of premature chromosome condensation (PCC) of the sperm nucleus with remarkable variation in the degree of condensation. Thus, it appears that nearly all round-headed sperm from this patient were incapable of oocyte activation after ICSI, which could be due to non-release (or absence) of an activating factor. As a consequence, PCC was induced in the sperm nuclei by the chromosome condensing factors which were still active in the oopasm of the arrested oocytes.

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