Caracterización citogenética molecular de las células germinales masculinas en la azoospermia secretora: parada de la maduración

About one third of non-obstructive azoospermic cases are due to maturation arrest (MA). The question of why some cases have a few germ cells that escape the meiotic block and form spermatozoa (incomplete MA) whereas others completely arrest at meiosis (complete MA) remains to be determined. In the present study we compared both situations through FISH analysis of sex (X, Y) and autosomal (7, 18) chromosomes in pure populations of stage-specific germ cells. Sertoli cells, primary spermatocytes, secondary spermatocytes, round spermatids and elongated spermatids were isolated by micromanipulation from fresh testicular biopsies of 7 patients with obstructive azoospermia (controls) and 20 patients with MA (9 complete MA, 11 incomplete MA). All the patients had normal secondary sexual development and karyotypes, and absence of endocrine disorders and Yq11.2 microdeletions. Incomplete MA was characterized by increased levels of aneuploidy in Sertoli cells, decreased homologue pairing at meiosis I and an increased incidence of aneuploidy in secondary spermatocytes, thus suggesting that it may be caused by deficiencies in synaptonemal complex assembly. In contrast, complete MA was associated with increased levels of aneuploidy in primary spermatocytes, arising during mitotic divisions of spermatogonia, and normal pairing, thus suggesting that meiotic arrest might be due to deficiencies in mismatch DNA repair.