46 THE NASAL ACCESSORY SINUSES IN MAN 



CELLULE ETHMOIDALES ANTERIOR 



Primitive cells of the anterior ethmoidal group develop 

 earlier and more rapidly than those belonging to the pos- 

 terior group. In the anterior group the bullar cells are 

 usually the first to be distinctly demonstrable. It was 

 found that in this series 81.7 per cent, of the bullar cells had 

 their origin from the suprabullar furrow, and 18.3 per cent, 

 from the infrabullar furrow. In a small percentage of fetal 

 as well as postnatal cases a shallow groove or furrow was 

 found on the inferomedial surface of the bullar fold, but in 

 no such case was the invagination sufficiently deep to be 

 indicative of actual cell formation. 



During the fourth fetal month there is also demonstrable 

 an expansion of the meatus medius which extends in an 

 anterosuperior direction, forming the recessus frontalis of 

 Killian. We believe that the study of the cellulae eth- 

 moidales anterior and the relations of the ostia frontalia 

 is simplified by subdividing this recess as follows: (a) That 

 portion of the recess lying lateral to the processus uncina- 

 tus is the anterior portion of the infundibulum, and will be 

 termed the recessus infundibularis. From this recess 

 smaller invaginations are demonstrable in late fetal and in 

 early childhood specimens. These invaginations are the 

 primitive cellulse infundibulares. (6) That portion of the 

 recessus frontalis lying medial to the processus uncina- 

 tus forms a concavity beneath the extreme anterosuperior 

 attachment of the concha media, and will be termed the 

 recessus conchalis. On the superior portion of the antero- 

 lateral wall of the recessus conchalis a large majority of late 

 fetal and early childhood specimens show from one to three 



