EMBRYOLOGICAL DEVELOPMENT OF THE ETHMOID SINUS IN CHINESE / 解剖学报

ABSTRACT

106 ethmoidal specimens ranging from 12 to 40 weeks of embryonic age were cut into serial sections and observed by histological method. The results showed that the ethmoid sinus began its development at about 21-23 weeks of fetal life. The frontal folds or furrows were formed by extensions or evaginations of the nasal mucous membrane from the superior and lateral wall of the middle and superior nasal meatuses. The ethmoid cells appeared at 24-26 weeks and they kept their own small ostia that opened into the middle and superior nasal meatuses. The number and size of the ethmoid cells were increased with the age. The cell cavities showed balanced enlargement. At birth each ethmoid labyrinth had 6-11 cells, measuring on the average 1.7?1.3?2.0 mm~3 in size. The distribution of the ethmoid cells approached those of mature age. The epithelium of the ethmoid sinus was cuboidal or low columnar in shape. Cilia appeared sparse. Tunica propria, mainly composed of the connective tissue and its stroma, was thick, loose, and less vascular and glandular. It suggested that the ethmoid sinus was one of the accessory nasal sinuse that developed first. The ethmoid sinus presented at birth and its appreance were not synchronous, but their location were relatively invariable. The histological structure of the mucous membrane in the ethmoid sinus was somewhat different from those of the nasal mucous membrane. It showed that the development of the ethmoid mucous membrane was still imperfect in the newborn.