Mammalian spermatogenesis in the seminiferous tubules of the testes is a unique developmental process of cell differentiation. The periodic spermatogenic processes originate from unipotential stem cells. The progenitor cells proceed to the spermatogonial proliferation stage, and then the spermatogonia differentiate into meiotic spermatocyte stages. Finally, the resulting haploid spermatids change their shape to that of mature spermatozoa. Buy Advair Diskus Online
These serial processes for forming male gametes are basically controlled by the programmed expression of a number of stage-specific genes, some of which have so far been identified as spermatogenic specific genes. Examining the molecular mechanism controlling the specific expression of these genes should shed light on regulatory network of spermatogenesis. However, the lack of an in vitro culture system that can reproduce each step of spermatogenesis has impeded progress in analyzing the regulatory mechanisms of such genes. Transcriptional regulatory elements of a restricted number of genes (e.g., Protamine-1, Protamine-2, Pgk-2, Hox-1.4, Zfy-1) have been clarified by producing a series of transgenic mice. The transgenic method, however, involves laborious and expensive work.