Differential expression of the mouse homeobox-containing gene Hox-1.4 during male germ cell differentiation and embryonic development.

Hox-1.4 is a mouse homeobox-containing gene (initially identified as HBT-1), whose expression appears to be testis-specific in the adult animal. Examination of Hox-1.4 transcripts in RNA from testes of mutant mice deficient in germ cells confirms that Hox-1.4 expression within the testis is germ cell-specific. Enriched populations of spermatogenic cells were used to localize the expression of Hox-1.4 specifically to germ cells that have entered into and progressed beyond the meiotic prophase stage of differentiation and to demonstrate the presence of two different size Hox-1.4 transcripts. Examination of RNA from teratocarcinoma cell cultures and mouse embryos at 10.5-16.5 days of gestation demonstrated the presence of several Hox-1.4 transcripts, which are larger than those present in germ cells. In the midgestation fetus, Hox-1.4 expression is most abundant in the spinal cord.