A de novo reciprocal translocation 46,X,t(Y;1)(q12;q12) was found in an azoospermic male with meiotic arrest. Cytogenetics and fluorescent in situ hybridization (FISH) were used to define the karyotype, translocation breakpoints and homologue pairing. SRY (Yp), Yq11.2-AZF regions, DAZ gene copies and the distal Yq12 heterochromatin were studied by PCR and restriction analysis using sequence-tagged sites and single nucleotide variants. High resolution GTL, CBL and DA-DAPI staining revealed a (Y;1) translocation in all metaphases and a normal karyotype in the patient's father. FISH showed the presence of the distal Yq12 heterochromatic region in der(1) and loss of the heterochromatic region of chromosome 1. PCR demonstrated the intactness of the Y chromosome, including the SRY locus, AZF regions, DAZ genes and distal heterochromatin. A significant decrease (P = 0.005) of Xp/Yp pairing (18.6%), as compared with controls (65.7%), was found in arrested primary spermatocytes, and cell culture and mRNA expression studies confirmed an irreversible arrest at meiosis I, with induction of apoptosis and removal of germ cells by Sertoli cells. We characterized a de novo t(Y;1)(q12;q12) balanced reciprocal translocation with loss of the heterochromatic region of chromosome 1, that caused unpairing of sex chromosomes followed by meiosis I arrest, apoptotic degeneration of germ cells and azoospermia.

In vitro culturing of normal human seminiferous epithelium remains largely unexplored. To study normal human spermatogenesis in vitro, we used a micromethod for the purification and culture of Sertoli cells, spermatogonia A, spermatocytes, and early round spermatids. Cytological quantitative data for Sertoli and premeiotic germ cell cocultures isolated from normal testicular biopsies demonstrated that cells were able to proliferate (4%), complete meiosis (6.7%), and differentiate into late round (54%), elongating (49%), and elongated (17%) spermatids at similar in vivo time delays (up to 16 days) in response to FSH + testosterone stimulation. Cells maintained normal meiotic segregation, chromosome complements, and specific gene expression profiles. Follicle-stimulating hormone + testosterone stimulated spermatogonia proliferation and Sertoli cell survival. Follicle-stimulating hormone and especially FSH + testosterone increased diploid germ cell survival during the first week, whereas only FSH + testosterone was able to inhibit cell death during the second week of culture. Follicle-stimulating hormone and especially FSH + testosterone also stimulated meiosis resumption, although this was restricted to late pachytene and secondary spermatocytes. In contrast, spermiogenesis was only stimulated by FSH + testosterone. Expression studies showed that apoptosis was induced in the nucleus of diploid cells, and in nuclear and cytoplasmic compartments of spermatids, mainly triggered by the Fas pathway. Although junctional complexes between Sertoli and premeiotic germ cells were partially reacquired, the same did not apply to spermatids, suggesting that FSH potentiated by testosterone was unable to render Sertoli cells competent to bind round spermatids.