54 THE DEVELOPMENT OF THE SALIVARY GLANDS IN MAN 



The free duct of the submaxillary descends with a caudal and slightly 

 lateral inclination, and escaping from the embrace of the Ungual nerve 

 and its ganglion, plunges into a sharply circumscribed retort-shaped 

 mass of dense mesench^nne (Figs. 16-18), which incloses all the branches 

 of the gland. An important though inconspicuous element occurs 

 in the course of the duct, while it is still in intimate relation with the 

 submaxillary ganglion. Vertically beneath the postglandular flange, on 

 the dorsolateral aspect of the convex curve of the duct for a section 

 or two on each side is found a shght enlargement partially constricted 

 from the rest of the duct, but showing no e\idence of sprouting 

 (Fig. 16, 12). Like the postglandular flange tliis appears to be a 

 remnant of the original flange of the submaxillary left adherent to the 

 duct when it became free. The branches of the gland fall into three 

 sets,, each composed of several buds irregularly arranged upon a short 

 common stem. The one in continuation of the line of the duct is the 

 largest. Of intermediate size is a dorsal, caudally directed complex. 

 These two groups e\'idently correspond to the two primary branches 

 of Cliievitz's 8 weeks embryo. A third smaller group arises from 

 the concavity of the duct, ventral to the lingual crossing and the mylo- 

 hyoid muscle; these sprouts are directed craniad. 



With respect to the presence of a lumen in the submaxillary duct, 

 the appearances in tliis embryo raise some questions of interpretation. 

 The gland sprout together with its branches is solid, as is also the pre- 

 lingual keel which continues the anlage craniad along the fundus of 

 the Ungual sulcus. The intermediate region alone offers difficulties. 

 Here a high flange is prolonged ventrad from the sulcus, which is 

 reduced to a shallow indentation of the base of the flange, a portion 

 of which in consequence appears to be formed by the apposition of the 

 walls of the sulcus. Since in this embryo a periderm layer is every- 

 where present in the mouth, the contact of the walls must be in detail 

 that of their periderm layers, the bulging nuclei of wliich interlock along 

 the Une of the obliterated lumen, and destroying sharp surface contours 

 make it impossible to be sure that actual fusion of the layers has taken 

 place. In some sections a pale streak may be seen in the axis of the 

 flange; in a few, the pale area widens irregularly and suggests the 

 presence of a space between the periderm cells. The distal or aboral 

 edge of the flange, and the prelingual keel and duct with which it is 



