The mesenchymal specificity of epithelium from the submandibular salivary gland of embryonic mice was re-investigated employing standard epithelio-mesenchymal separation and recombination techniques. For this purpose, tissue recombinants were constructed with epithelium and mesenchyme of the submandibular salivary gland and the seminal vesicle, preputial gland, and urogenital sinus. Salivary glands were dissected from 13-day and the accessory sexual glands from 13– to 19–day old embryos. Tissue recombinants were grown for two to three weeks in the anterior chamber of the eye of adult male hosts.

Mesenchyme from accessory sexual glands supported the growth, branching, and differentiation of epithelium from the salivary gland. After three weeks of intraocular growth, most of these heterotypic recombinants were indistinguishable from intraocular grafts of this gland. However, recombinants constructed with mesenchyme from the urogenital sinus or preputial gland exhibited an age dependent developmental response. Mesenchyme from 15- to 16-day old embryos supported normal morphogenesis of the salivary gland, whereas atypical epithelial differentiation occurred when 13- or 14-day old mesenchyme was employed. On the other hand, the reciprocal recombinants composed of mesenchyme from the salivary gland and epithelium derived from accessory sexual glands resulted in abortive epithelial differentiation regardless of the age of the tissues. These results suggest that the mesenchymal specificity of epithelium from the salivary gland may be related to the morphogenetic sensitivity of the heterotypic mesenchyme to androgens.