OSTIA NASOLACRIMALIA IN MAN 191 



Anlage of the naso- 

 lacrimal passages 

 entirely isolated 

 from the surface 



Fig. 14 Outline drawing of a frontal section through the developing ductus 

 nasolacrimalis (human embryo). The duct is represented as solid. Note the 

 very extensive coalescence of the duct with the nasal mucous membrane. Com- 

 pare with figs. 12 and 13. 



Fig. 15 Frontal section through the nasal fossa and the anlage of the nasolac- 

 rimal passages, from a human embryo aged forty-three days. Note that the anlage 

 is entirely isolated from the surface. The ductus lacrimales have started to sprout 

 from the ocular end of the strand of epidermal cells. The nasal end of the strand 

 of cells has not developed sufficiently to come in contact with the nasal mucous 

 membrane. Especially note the lateral buds from the main strand of cells. 

 X 16.5. 



The case of Geddes, in which the ductus nasolacrimalis com- 

 municated with the meatus nasi medius, can be explained by a 

 lateral bud from the main strand (fig. 15). In such a case the 

 accessory or lateral bud, instead of ending blindly or developing 

 sufficiently to establish communication -with the meatus nasi 

 inferior, established connections with the meatus nasi medius. 

 For some reason or other, the nasal end of the main strand of cells 

 did not establish connections with the meatus nasi inferior. If, 

 on the other hand, the connection was established, the cord not 

 becoming canalized, would in all likelihood undergo resorption 

 caudal to the sprout which established the definitive connections 

 with the meatus nasi medius. That Geddes was dealing with a 

 true portion of the ductus nasolacrimalis and not with a false 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 13, NO. 2 



