Relationship Between Sperm DNA Fragmentation and Nuclear Vacuoles

The aim of the present study is to assess the correlation between the presence, quantity and size of nuclear vacuoles and DNA damage and chromatin status in sperm samples of men who underwent to assisted reproduction technology.

Forty six males who underwent to assisted reproductive technology (ART) were considered. According to their latest semen analysis (<3 months), were grouped into: (A) strict morphology index ≤4% (26) and (B) strict morphology index ≥14% (20). Motile sperm were selected by density gradient, and MSOME study was conducted to assess the number and size of nuclear vacuoles. DNA fragmentation (TUNEL) and DNA strand status (acridine orange) were assessed over the selected spermatozoa accordingly to their vacuole pattern.

In group A, sperm without vacuoles (1°) have similar levels of DNA fragmentation (TUNEL) in compare to the rest of observed patterns (2°- 6°). Regarding to AO, spermatozoa with large or several vacuoles that cover more than 30-50% of the nuclear surface are AO+, but not necessarily TUNEL positive. The first three patterns of vacuoles patterns had lower levels of AO in compare to grades 4° and 6°. In group B, those sperm with one or more vacuoles greater than 30%-50% (4° and 6°), had a significant increase in TUNEL values, in relation to group 1°- 3°. Considering AO, it was found that the 4° and 6° pattern had a significantly elevated level of this marker, as same of group A (P <0.05).

There is no relationship between the greater number and size of sperm vacuoles with high levels of DNA fragmentation in patients with severe teratozoospermia (Kruger <4%). Conversely, this relationship is evident in normal semen samples (normal morphology. Sperm selection by IMSI technique, to select non-fragmented sperm in patients with Kruger <4%, is not necessarily secured when non-vacuolated sperm is selected.