DEVELOPMENT OF EYELIDS OF ALBINO RAT 



15 



that the first opening between the two palpebral margins will 

 appear about the median portion of the lids. From here the 

 opening process continues toward both the inner and outer 

 canthus, usually reaching the former first. Outlets of some of 

 the tarsal glands were open at this time, while in other cases a 

 plug of cornified epithelium still occluded the mouths of the 

 ducts. 



'^^r 



Fig. A Photograph of section through margins of lids of albino rat thirteen 

 days old, showing the lids connected by only cornified epithelium, and hence 

 nearly ready to separate. Hair follicles occupy the entire thickness of the lids, 

 except for a narrow zone on the conjunctival side where the tarsal glands (t) 

 are situated, x marks position of outlet of duct of tarsal gland. X 50. 



Thirteen-day rat 



The loosely arranged keratinized epithelium still connects the 

 two lids (fig. A), but forms an extremely thin membrane. Its 

 texture is less compact than at the preceding stage, its elements 

 being curled and irregular and spread apart. The outlets of 



THE AMERICAN JOURNAL OF ANATOMY, VOL 29, NO 1 



