DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 265 



glandular mass of the orbit presents its base to the oral cavity in the 

 mesal part of the triangle, between the masseter laterad, the internal 

 pterygoid mesad, and the margin of the hard palate craniad. This area 

 appears pale in cats in wliich the pigmentation of the epithelium is not 

 excessive, the orbital gland mass and suborbital fat being here close 

 to the transulcent mucosa. It may conveniently be termed the triangle 

 of the orbital glands, although they occupy only its mesal half, the 

 remainder corresponding to the delicate suborbital fat in which the 

 glands are embedded. The massa orbitaUs is composed of several 

 elements which diminish in size caudad. Three are well developed in 

 the cat and have ducts prolonged craniad in the mucosa to orifices 

 considerably in advance of their respective bodies. These ducts 

 pierce the buccinator to bend craniad into a course which carries 

 them obliquely along the stomal fold, a ridge extending from the 

 parotid orifice caudad to the tuberosity of the superior maxillary, where 

 it turns mesad and caudad, diminishing in size as it approaches the 

 triangle of the orbital glands, where it stops. The first duct opens 

 close beside the last cusp of the carnassial, the second just behind the 

 molar, and the third a very short distance further caudad, at the point 

 where the deep facial vein crosses the lateral angle of the triangle of 

 the glands. It is, then, the third orbital which in the adult corresponds 

 to the vein ; in this point the embryo presents differences which 

 are described below in detail. Between the orifices of these larger 

 orbital ducts a few minute mucous glands open along the ridge. 

 All of the ducts open laterad to the internal pterygoid and are, there- 

 fore, to be assigned to the vestibule, and in particular to its short 

 postdental portion, which by reason of the obliquity of its lateral wall 

 is narrowing rapidly toward the fauces. 



A corresponding contraction of the cavity occurs in the embryo from 

 an early period, at the point where the buccal sulcus begins its mesal 

 sweep, and at the same time begins its descent from the crown of its 

 sagittal arch. It was found convenient to designate this region of 

 changing direction the orbital angle, from its relation to the broad 

 portion of the orbital inclusion. Here also the superior dental ridge 

 dwindles and finally ends. In this region the anlage of the first orbital 

 gland appears as a sohd ridge of cells projecting from the dorsal wall 

 of the buccal sulcus close to, but not at, its fundus (Fig. 146, 26). The 



