SIMULTANEOUS DIFFERENTIAL STAINING OF CARTILAGE AND BONE IN RODENT FETUSES - AN ALCIAN BLUE AND ALIZARIN RED-S PROCEDURE WITHOUT GLACIAL ACETIC-ACID

Differential staining of cartilage and bone has several applications i ncluding developmental toxicology studies of new chemical candidates f or pharmaceutical, industrial, and environmental use. It has been more common to stain fetal bone only using the dye alizarin red S; however , failure to evaluate the cartilaginous portion of the skeleton may re sult in the failure to identify toxicologically important alterations in skeletal morphology. Previously, differential staining of fetal car tilage and bone was best achieved by combining alizarin red S for stai ning bone with alcian blue to stain cartilage in glacial acetic acid s olution; however, occupational hazards posed by the use of glacial ace tic acid make these methods undesirable. Replacement of the glacial ac etic acid with potassium hydrogen phthalate eliminates these hazards w ithout compromising the quality of the stained specimen.