Figs. 17-21 Photomicrographs of frontal sections through the nasolacrimal 

 passages of a human embryo aged one hundred and twenty days. Note the solid 

 portions of the lacrimal ducts in fig. 17. In fig. 18 we have a patent section {Is) 

 of the ocular end of the nasolacrimal duct, and in fig. 1!) a section of the mid-por- 

 tion of the nasolacrimal duct, still solid {nld). Note the well established lumen 

 {nld) at the nasal end of the nasolacrimal duct in figs. 20 and 21. Note how exten- 

 sive the contact point between the nasolacrimal duct and theinferior nasal meat us 

 will be (fig. 21). sld = superior lacrimal duct; ild = inferior lacrimal duct; Is = 

 lacrimal sac; nlil = nasolacrimal duct ; inc = inferior nasal concha; inm = inferior 

 nasal meatus. X 10. 



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