THE DEVELOPMENT OF THE SALIVARY GLANDS IN MAN 6l 



tal of the lingual crossing, while the hngual and prelingual portions of 

 the duct correspond to the tliickened border of the flange. In Fig. 

 25 these conditions are indicated schematically. The triangular an- 

 lage is represented as giving rise to the duct along its hypothenuse and 

 to the bud at its free angle. The area between the dotted lines is lost 

 in freeing the duct. Along the lingual sulcus and along the duct the 



Fig. 25. Schema of anlage of subma-xiUary. Stage of 13-14 millimeters. Embryos 



2, 4, 6, and 7. 



9. Submaxillary sprout. 13. Postglandular flange. 



12. Dorsal accessory submaxillary. 30. Lingual nerve. 



areas defined by the dotted hnes escape reduction at this period, and 

 represent respectively the postglandular flange (/j) and the dorsal 

 accessory submaxillary (12). 



From the angle of the flange, proliferation advances along its free 

 margin and eventually reaches the unfolded fundus of the lingual sul- 

 cus, where it forms a soUd epitheUal crest. At the same time the sprout 

 at the angle enlarges and begins to invade the mesenchyme. This 

 condition is attained in the 13.8 millimeter embryo of Paulet, and car- 

 ried further in Hammar's embryos of 17 millimeters and 18.5 milli- 

 meters. In Chievitz's embryo of 8 weeks the attachment is described 

 as a crest. In the 20 millimeter embr>'o of the Columbia Collection 

 both crest and flange are present. In the region of the Hngual crossing 

 the hngual sulcnis is reduced to a shallow furrow, a character which it 

 retains in the whole length of the postglandular flange, caudal to which 

 it regains its lumen. Craniad the flange becomes smaller and very 



