Enhanced Detection of Methyl Methanesulfonate–Induced Sperm Lesions in Rats Using Laser Scanning Microscopy

Abstract

Male Wistar Crl: WI(Han) rats received 40 mg methyl methanesulfonate (MMS)/kg body weight (5 mL/kg) for five consecutive days. After a three-week recovery period, all animals were terminated, and sperm was collected from vasa deferentia (adjacent to cauda epididymidis) and cauda epididymidis. Sperm was analyzed for vital parameters and by light microscopy. Samples were also collected for laser scanning microscope (LSM) evaluation. Findings comprised changes in cytoplasmic droplets (reduced number, misplacement), sperm head abnormalities (pyknosis, misshapen, elongated, stretched, thickened or thinned), curvature abnormalities (kinked, coiling, one double-headed sperm), sperm tail abnormalities (coiling, spiral winding, fusion of outer layers of tails between two sperm cells), sperm tail core (axoneme and dense fibers) abnormalities (doubling and branched structures), and outer layer of tail abnormalities (partial or complete loss, formation of bulging structures). Findings induced by the genotoxic substance MMS generally confirmed those published previously. LSM can help visualize morphological details as counterparts of the genotoxic and cytotoxic effects of MMS. LSM permits high magnifications, rapid analysis of large numbers of sperm, precise morphological details, and fewer diagnostic artifacts, consequently preventing some missed or misdiagnoses, and making it superior to classical light microscopy for morphological sperm analysis.