Meiotic Arrest and Synaptonemal Complex Failure in Infertile Men with Y Chromosome Microdeletions

Abstract

Background: The Y chromosome microdeletions are common genetic cause of male infertility. Mechanisms of impaired spermatogenesis and meiosis, as well as phenotypic variability, have not been sufficiently studied.

Objective: The paper provides results of the spermatogenesis and meiotic study based on the analysis of synaptonemal complex (SC) in the spermatocyte nuclei in infertile men with Y chromosome microdeletions.

Materials and methods: Examined cohort consisted of 9 male patients 27-32 years old with primary infertility with non-obstructive azoospermia. The patients had a 46,XY karyotype, complete (n = 4) and partial AZFc (n = 2) deletions, and complete AZFb (n = 2) and AZFb+c (n = 1) deletions. Semen analysis was performed and assessed according to the WHO guidelines (WHO, 2010). The AZF deletions were detected by multiplex PCR, analyzing Y-specific loci in accordance with the guidelines for molecular diagnosis of the Y chromosome microdeletions. Testicular biopsy was performed by with the TESE technique. Testicular tissue fragments were assessed under a light microscope for the presence of spermatocytes, spermatids, spermatozoa, atypical and degenerating germ cells in the suspension and analyzed by histopathology. Immunostaining was performed using antibodies to the SYCP3, γH2AFX, RAD51, and MLH1 proteins.

Results: In 6 examined patients, spermatocytes were found at following stages of the prophase I of meiosis: leptotene - 32.3 ± 39.4 (0-100)%, zygotene - 17.4 ± 20.1 (0-63.6)%, pachytene - 48.6 ± 38.2 (0-100)%, diplotene - 1.8 ± 2.2 (0-5.6)%. Percentage of germ cells at these stages was very close between patients with AZFb, AZFb+c, and AZFc deletions. Meiotic arrest at the zygotene stage with atypical SCs and incomplete synapsis in all nuclei was found in patient with complete AZFb+c deletion. Complete meiotic arrest at early-mid-pachytene was characterized for complete AZFc and AZFb deletions. Azoospermic patients with partial AZFc (gr/gr) deletions had incomplete meiotic arrest at the mid-pachytene stage.

Conclusion: Our own and literature data indicate more severe spermatogenesis and meiosis failures in patients with AZFb+c and AZFb deletions in comparison with AZFc deletions. Meiotic arrest at early-mid-pachytene was common, but some variability was found in the severity of spermatogenesis abnormalities in patients with complete AZFc deletions that requires further research.

Keywords: Azoospermia factor; Germ cells; Male infertility; Meiosis; Meiotic arrest; Microdeletions; Spermatogenesis; Synaptonemal complex; Y chromosome.