. The American journal of anatomy . he cord. The lacrimal-ductcords have also established lumina at various points, especiallyin the regions of the knees, or what will later become the ampullaeof the lacrimal ducts. In figs. 14, 15 and 16 (embryo aged one hundred and seven days)is well illustrated the irregular manner in which the cords of epi- Figs. 14, 15, and 16 Photomicrographs of frontal sections through the naso-lacrimal passages of a human embryo aged one hundred and seven days. Noteboth lacrimal ducts (fig. 14) in contact and fused with the epidermis in the regionof the free borders of
. The American journal of anatomy . he cord. The lacrimal-ductcords have also established lumina at various points, especiallyin the regions of the knees, or what will later become the ampullaeof the lacrimal ducts. In figs. 14, 15 and 16 (embryo aged one hundred and seven days)is well illustrated the irregular manner in which the cords of epi- Figs. 14, 15, and 16 Photomicrographs of frontal sections through the naso-lacrimal passages of a human embryo aged one hundred and seven days. Noteboth lacrimal ducts (fig. 14) in contact and fused with the epidermis in the regionof the free borders of the eyelids. The lacrimal ducts have not yet establishedlumina in the regions of the eyelids (fig. 14). The remaining portions of the ductsare more or less patent throughout. Note the irregularity of lumen formation inthe nasolacrimal duct (fig. 16). sld = superior lacrimal duct; ild = inferior lacri-mal duct; eld = common lacrimal duel ; Is = lacrimal sac; nld = nasolacrimal GENESIS OF NASOLACRIMAL PASSAGES IN MAN 15. n/d 16 J. PARSONS SCHAEFFER thelial cells establish lumina. Note that the lacrimal ducts aremore or less patent throughout, save at the free borders of theeyelids where solid cords still persist. The horizontal and verti-cal portions of the lacrimal ducts are well shown (fig. 14). Thelacrimal sac (fig. 15) is well advanced but the remainder of thenasolacrimal duct is not wholly patent. Even at this early stagethere is some evidence of beginning diverticula from the naso-lacrimal duct (fig. 16). The connection with the inferior nasalmeatus is, of course, not yet established (fig. 16). According to my studies, the ocular end of the mother cordis the first to establish a lumen. The horizontal portions of thelacrimal ducts become patent before the vertical portions ( and 17). The last parts of the vertical portions of the lacri-mal ducts to become patent are the junction points between thelacrimal-duct cords and the epithelium of the free borders
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1912
