292 DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 



it has several branches, which are given off from the convex aspect of the 

 duct and have a dominantly caudal direction (Fig. 140). Throughout 

 the period covered by our series the submaxillary far exceeds in volume 

 the other saHvary glands. The mesenchymal condensation which is 

 common to it and the greater sublingual is a retort-shaped object 

 (Fig. 106), the neck of which enters the interval between the digastric 

 muscle and Meckel's cartilage, when, becoming less definite, it is con- 

 tinuous with the supramylohyoid mesenchyme. Its fundus rests against 

 the lateral surface of the digastric, ventral of the masseter at its caudal 

 angle, where it comes close to the branches of the parotid. The two 

 glands in these sections present a marked contrast in appearance, the 

 parotid sprouts l>'ing free in almost unaltered mesenchyme (of a capsule 

 or common condensation there is no trace), while the branches of the 

 submaxillary are contained in a dense and sharply circumscribed area 

 of very richly nucleated young connective tissue. 



The mesenchymal condensation antedates the emergence of the 

 sprout from the mylohyoid girdle. In the early stages its outline 

 is a little vague, and there is a zone of transition to the less dense sur- 

 rounding tissue. The Umits gradually become better defined, and in 

 late stages receive further emphasis from a series of circumferential 

 lymph spaces. 



THE GREATER SUBLINGUAL GLAND 



Of the primitive epithelial placode of the floor of the mouth a por- 

 tion persists in the vicinity of the submaxillary ganglion. After the 

 appearance of the submaxillary flange, it forms a diffuse thickening 

 of the alveohngual fold, best marked near its middle and fading off 

 towards the tongue and alveolar process. In the midst of this area 

 the anlage of the greater subhngual appears as a rather indefinite 

 sagittal ridge. It is present in one of the embrj'os of 12 millimeters 

 (Figs. 127, jj), in two of 13.5 millimeters, and in two of the 14 miUimeter 

 embryos. In all of these the periderm and basal layers are well defined, 

 and the ridge of the greater subhngual (Figs. 153-156, jj) is seen to 

 be composed of the basal cells alone, which project beyond the general 

 surface of the epithelium and suffer some disturbance of their regular 

 arrangement. The periderm passes uninterrupted over the ridge ; 

 there is no fissure. Ventral to the ridge is a sHght diffuse thickening 



