The Junction of the Nasal Cavity and the Pharyngeal Tube in the Rat

IN THE COURSE of examinations of serial sections of the nasal passages of the rat, some peculiarities were noted, of which no reports have been discovered. These peculiarities are (1) a communication between the right and the left half of the nasal cavity at the choanal end of the respiratory part and (2) certain conditions at and near the junction of the nasal cavity and the pharyngeal tube. MATERIAL AND METHODS The heads of 40 young rats were examined. The animals, of different strains and of both sexes, ranged in age up to 100 days. Their weight averaged 210 Gm., with limits of 82 to 295 Gm. After decapitation, the heads were preserved in a solution of formaldehyde, U.S.P., diluted 1 to 10, for periods up to four weeks. Nitric, trichloroacetic or formic acid was used for decalcification. After the specimens had been embedded in paraffin, the frontal sections were