The DAZL1 gene is expressed in human male and female embryonic gonads before meiosis

The human DAZL1 gene (known also as DAZH or DAZLA) is the autosomal homologue of the Y-chromosomal DAZ gene which has been found to be deleted in azoospermic males. Evidence suggests that the role of DAZL1 may not be restricted to spermatogenesis, but may include oogenesis as well. In order to study the function of human DAZL1 gene in the ovary, we observed its expression pattern during embryonic development. RNA in-situ hybridization showed that DAZL1 transcripts were localized to a subset of cells (somatic versus germ cells) in human embryonic ovary (23 weeks of gestation) and testis (21 weeks gestation). In the ovary, DAZL1 transcripts were found in oogonia and in oocytes and granulosa cells of primordial follicles. In the testis, DAZL1 transcripts were identified exclusively in the germ cells. Our results demonstrate high similarity between the human DAZL1 and the mouse Dazl1 gene expression patterns during embryonic development, suggesting that the human gene functions at the first phase of gametogenesis, just as in the mouse, where Dazl1 mutations cause male and female sterility.