310 DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 



tion of the crest of proliferation. In the region of the flange rudimen- 

 tary structures appear (Figs. 141, 142), a postglandular flange repre- 

 senting its attached border, and an intermediate portion, which is 

 usually allotted to the duct. Both are ephemeral in the cat, and have 

 not been found to give rise to sprouts. 



The greater sublingual gland is the result of a process of proliferation 

 initiated caudal to the lingual nerve, lateral to, and distinctly separate 

 from, the submaxillary anlage, of which it is perfectly independent 

 throughout development. It appears as a ridgelike thickening in the 

 midst of a remnant of the primitive placode, and advances as a keel 

 along the floor of the alveolingual region. Its duct is freed by con- 

 striction. The distal sprout is relatively late in assuming active 

 growth. 



The lesser sublinguals in the 70 miUimeter embryo are represented 

 by three hemispherical sprouts in the preUngual segment of the circum- 

 flex sulcus (Fig. 114). The gland field of the alveohngual region re- 

 solves itself into three sagittal gland lines : mesal, the submaxillary, 

 intermediate, the greater subhngual, lateral, the lesser sublinguals. 



9. In the 70 millimeter embryo (Fig. 114) the simple sprouts of 

 the small diffuse glands of the mouth are for the first time present. 

 These are the lesser subUnguals, the caudal members of the orbital 

 series, the glands of the stomal ridge, isthmian, faucial, and palatine 

 glands. 



10. As regards the developmental process, the salivary glands are 

 either simple sprouts, or in addition to the sprout have keeled exten- 

 sions along the oral epithelium. The latter are termed complex glands, 

 and are regarded as equivalent to condensed rows of simple sprouts. 

 To this class belong the parotid, the submaxillary, the greater sublin- 

 gual, the first three orbitals, and possibly some of the orbitoparotid ele- 

 ments. Two glands of this class are in early development associated 

 with a flange, the parotid and submaxillary. Their permanent struc- 

 ture is like that of the other glands, the result purely of proliferation. 

 The flanges seem only to accelerate their development, as shown by 

 their early appearance and rapid growth, and serve to guide the 

 crests which give rise to the ducts. In contrast to the flanged 

 glands, the growth of the sprouts of the other complex glands is late 

 in begirming (greater subhngual, orbitals I, II, III). 



