. The science and practice of dental surgery. relacrimal duct. During the fifth weekthe mandibular pro-cesses unite ventrally toform the mandibulararch, and a week later process are formed the central portions of thepre-maxillae (endognathia), or that portioncarrying the central incisor teeth, a correspond-ing portion of the upperlip, and the septum andbridge of the nose. Fromeach lateral nasal processare formed tlie lateral por-tion of the pre-maxilla(mesognathion), or that por-tion carrying the lateralincisor tooth, a correspond-ing portion of the upperlip (except its free margin),and the al
. The science and practice of dental surgery. relacrimal duct. During the fifth weekthe mandibular pro-cesses unite ventrally toform the mandibulararch, and a week later process are formed the central portions of thepre-maxillae (endognathia), or that portioncarrying the central incisor teeth, a correspond-ing portion of the upperlip, and the septum andbridge of the nose. Fromeach lateral nasal processare formed tlie lateral por-tion of the pre-maxilla(mesognathion), or that por-tion carrying the lateralincisor tooth, a correspond-ing portion of the upperlip (except its free margin),and the ala of the processes, with thenaso-frontal process, formthe OS incisivum (Albrecht)and complete the anteriornares. The incisive bone,according to Kolliker, isformed entirely from thenaso-frontal process. The greater portion ofthe maxiUa, containing theremaining teeth (exognathion), results from ametamorphosis of the maxillary process. Themaxillary process likewise forms the zygomaticand palatine bones, a corresponding portion of SpC. BP SpM Soli Fig. 5.—Longitudinal section of a developing ovum about the end of the secondweek (from Cunningham). The folding off of the embryo has commenced, andthe downward bend of the head fold has invaginated the amniotic tail fold is partly formed, and the primitive alimentary canal, closedin front by the bucco-pharyngeal membrane and behind by the cloacalmembrane, is distinguishable; it communicates freely with the yolk sac bya wide umbilical aperture,^t,;^!, +. -^hZc.~\^^ C, Coelom; EN, Entoderm; SoM, Somatic mesoderm; EC, Ectoderm; M, Moso-umon takes piace oe- derm; SpM, Splanchnic mesoderm ; BP, Buoco-pharyngeal membrane; PA. tween the naso-frontal, ~ ? ? .r, .__ r_ij . ^»t, t,:j „:„. c„,. c.,:.,„i —j.,ii~. lateral nasal, and maxil-lary processes, but insuch a way that thelateral nasal processes fallshare in the formation of Placental area; AF, Amniotic fold; MB, ilid-brain; SpC, Spinal medul
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdentistry, bookyear19
