HISTOLOGY 



109 



The main duct leads toward the posterior corner of the eye. Here the 

 duct joins the intra-orbital lacrimal gland which consists of a small lobe, and 

 is identical structurally with the exorbital gland. 



'^^9^^ 



-Alveolus 





■Blood vesse 



Duct 



Fig. 47. — Exorbital lacrimal gland. (X200.) 



Harderian glands. — The Harderian gland lies behind the eyeball and 

 partially encircles the optic nerve. It is tubulo-alveolar in structure 

 (Fig. 48). A thin connective tissue membrane surrounds and divides the 

 gland into lobes and lobules. The tubules and alveoli are lined by tall 



Fig. 48. — Harderian gland. (X200.) 



columnar epithelial cells in which the pale staining round nuclei are at the 

 bases of the cells. The cytoplasm contains minute fat droplets which are 

 seen in sections as small vacuoles, separated from each other by acidophilic 

 granules. In many tubules the cells are broken down and the lumina con- 

 tain a fatty secretion which is the product of cell degeneration. 



The gland cells rest on a delicate lamina propria, the cells of which 

 occasionally contain pigment granules. The pigment may color the secre- 

 tion present in the lumina and is visible grossly as small dark granules and 



