Sperm chromatin anomalies can influence decondensation after intracytoplasmic sperm injection

Abstract

In this study we investigated whether morphology and chromatin anomalies in human spermatozoa can influence fertilization after intracytoplasmic sperm injection (ICSI). We examined unfertilized oocytes, using the flnorochrome Hoechst 33342, to determine whether a relationship exists between failure of fertilization and sperm chromatin quality. Sperm chromatin packaging quality was assessed using the chromomydn A 3 (CMA 3 ) fluorochrome, and the presence of DNA damage in spermatozoa, using in-situ nick translation. Normal males present sperm parameters with a normal morphology of >20%, CMA 3 fluorescence of <30% and exhibit endogenous nicks in <10% of their spermatozoa. When patients were separated according to these values no difference was observed hi their fertilization rates after ICSL When the unfertilized ICSI oocytes were examined, we found that patients with CMA 3 fluorescence of <30% and nicks in <10% of their spermatozoa had only 17.5 and 21.6% respectively of their unfertilized oocytes containing spermatozoa that remained condensed. In contrast, patients with higher CMA 3 and nick values had a significantly higher number, 412 and 48.9%, of their unfertilized oocytes containing condensed spermatozoa. Sperm morphology did not show any such pattern. The percentage of spermatozoa which had initiated decondensation in unfertilized oocytes was not influenced by morphology, CMA 3 fluorescence or nicks. In light of these results we postulate that poor chromatin packaging and/or damaged DNA may contribute to failure of sperm decondensation after ICSI and result in failure of fertilization.

CASA derived human sperm abnormalities: correlation with chromatin packing and DNA fragmentation

“…Any deviations in this maturation process of replacement of histones by protamines may result in poor chromatin packing and severe morphologically abnormal sperms, having a significant influence on fertilization rate [24,49]. Similarly, several studies have confirmed that poor chromatin packing may lead to sperm decondensation failures post ICSI which affects the fertilization process [50][51][52]. Furthermore, several studies have also demonstrated a strong correlation between abnormal protamination and sperm DNA fragmentation [53][54][55].…”

Human Cervical Mucus Can Act in Vitro as a Selective Barrier Against Spermatozoa Carrying Fragmented Dna and Chromatin Structural Abnormalities

“…The existence of an association between sperm chromatin malformation and male infertility has been repeatedly observed in humans and structural chromatin abnormalities have been found to exert negative effects both on the percentage of fertilization and on embryonic development (17,(19)(20)(21).…”

“…During the last decade, a number of studies have shown that variable but consistent fractions of human spermatozoa not always detectable on the basis of classic morphological parameters, contain serious chromatin structural abnormalities and DNA strand breaks (12)(13)(14)(15)(16)(17)(18). The existence of an association between sperm chromatin malformation and male infertility has been repeatedly observed in humans and structural chromatin abnormalities have been found to exert negative effects both on the percentage of fertilization and on embryonic development (17,(19)(20)(21).…”

The ability of freeze-dried bull spermatozoa to induce calcium oscillations and resumption of meiosis

“…Alterations in sperm chromatin and/or DNA damage might result in defective decondensation and a delay in the formation of the male pronucleus [53,54]. A prolonged storage of FD spermatozoa at ambient temperatures may induce such alterations and/or DNA damage.…”