Meiosis I arrest and azoospermia in an infertile male explained by failure of formation of a component of the synaptonemal complex.

Objective: To characterize the early stages of meiosis in a male with unexplained azoospermia.
Design: Case report.
Setting: Case Western Reserve University and University Hospitals of Cleveland.
Patient(s): A 30-year-old male with nonobstructive azoospermia.
Intervention(s): Immunostaining for components of the synaptonemal complex and recombination-associated proteins, fluorescence in situ hybridization (FISH) for specific chromosomes.
Main Outcome Measure(s): Progression to and through pachytene of meiosis I in controls and in the patient.
Result(s): We observed complete meiosis I arrest in the patient, associated with failure of formation of the mature, tripartite synaptonemal complex.
Conclusion(s): Abnormalities in synaptonemal complex formation are responsible for a proportion of cases of unexplained male infertility.