Homeobox-containing (Hox) genes play important roles in development, 
particularly in the development of neurons and sensory organs, and in 
specification of body plan. The Hmx gene family is a new class of 
homeobox-containing genes defined by a conserved homeobox region and a 
characteristic pattern of expression in the central nervous system that is more 
rostral than that of the Hox genes. To date, three closely related members of 
the Hmx family, Hmx1, Hmx2, and Hmx3, have been described. All three Hmx genes 
are expressed in the craniofacial region of developing embryos. Here we show, 
for the first time, the expression of the transcription factor Hmx3 in 
postnatally developing salivary glands. Hmx3 protein is expressed in a cell 
type-specific manner in rat salivary glands. Hmx3 is present in both the nuclei 
and cytoplasm of specific groups of duct cells of the submandibular, parotid, 
and sublingual glands. Hmx3 expression increases during postnatal development of 
the submandibular gland. The duct cells show increasing concentrations of Hmx3 
protein with progressive development of the submandibular gland. In contrast, 
the acinar cells of the three salivary glands do not exhibit detectable levels 
of Hmx3 protein.