114 



BIOLOGY OF THE LABORATORY MOUSE 



The central intralobular ducts of both sexes are Hned by rodded epithelium. 

 In the adult female this type of epithelium also lines the terminal tubules 

 into which the central intralobular ducts divide (Fig. 50A). In the adult 

 male the lining of the terminal tubules and some of the alveoli opening into 

 them consists of tall columnar epithelial cells with the nuclei near and often 

 flattened against the bases (Fig. 50B). These cells resemble mucous cells 



Terminal tubule 



Central intralobular 

 duct 



Fig. 50. — Subm;i.\illary gland. A 



Terminal tubule 



Alveolus 



Central intralobular 

 duct 



]''emale mouse. B. Male mouse. (X200.) 



and are perhaps identical with the tropochrome cells described by Stormont. 

 They do not stain red with Mayer's mucicarmine stain. In young animals 

 of both sexes up to about live to seven weeks the structural differences do 

 not exist, and the tall, light staining cells are not present.* 



* The above is based on observations by the author and Paul Ossen. Since these 

 observations were recorded a recent paper by Lacassagne (65) which describes the same 

 dimorphic structural sex differences has come to our attention. 



