Adverse effects of formaldehyde vapor on mouse sperm parameters and testicular tissue

Formaldehyde (FA), one of the simplest organic molecules, is a flammable, pungent, irritating and colorless gas. This study aimed to investigate the effects of various concentrations of FA vapor on sperm parameters and testicular tissue.

In this experimental study, we randomly assigned 36 adult male mice to one control and two experimental groups (n=12 for each group). The control group (C) did not receive FA. Group F1 (low concentration) was exposed to 10 ppm FA vapor and the F2 (high concentration) group was exposed to 20 ppm FA vapor. FA was administered for ten days, eight hours per day for both groups. At the end of the exposure period, half of the animals in each group were sacrificed 24 hours after exposure to detect any short-term effects; the rest of the mice were sacrificed 35 days later to assess for long-term effects. Sperm parameters were analyzed by Computer-assisted Sperm Analyzer (CASA) and histological changes determined. In addition, we studied changes in testosterone hormone. Data were analyzed by one-way ANOVA followed by the Scheffe test using SPSS software.

Long-term effects of FA in the experimental groups included significant reductions in sperm cell numbers and sperm viability. A drastic reduction in progressive motility and increased abnormal sperm percentage (p<0.001) compared with the control group was also noted. Histological study of testes specimens in the experimental group revealed displacement of germinal cells, along with degeneration of Leydig cells and seminiferous tubules.

Exposure to FA vapor can destroy testicular structure and decrease percentages of concentration, viability, normal morphology, and progressive motility, in addition to increasing the percentage of immotile sperm.