胎児皮膚の分裂線と毛流との関係に就て
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概要
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A comparative observation has been conducted on the behavior of the splitting lines and the hair streams which occurred in the skin covering the head and back of the human embryo. Head region was observed on each stage of embryo from 5 to 8 months of age, and back region on each stage of embryo from 6 to 10 months of age, and thus chronological observation has been made possible to know the possible interaction occurring between the splitting lines and the hair streams in the course fetal life. The results obtained were summarized as follows. 1) In the following regions of the body the two anatomical traits showed similar patterns of orientation through every stages of embryonic life ; upper two third of the frontal, upper half of the orbital, the temporal, the parietal, and the occipital regions down to the line connecting the upper roots of right and left auricles ; lower lip and chin regions, upper half of mouth region, dorsal sides of the abdomen and the sacral region. 2) The regions where the splitting lines and the hair streams took different directions at early stages of life, but later shared the same direction due to bodily growth were as follows ; lower half of the orbital region, periphery of the auricle, cheek region and upper part of the scapular region. 3) There are regions where the splitting lines and the hair streams took the same direction only at certain periods of the fetal life. The regions and the months involved are as follows ; at 6 months the whirl of hair part of the parietal region, the vertebral region and its whirl of hair part ; at 6 and 8 months those parts extending from the scapular region toward its middle and lower regions. 4) The region where the splitting lines and the hair streams took different directions through entire stages of embryonic life is confined to the part which is bordered upward by the line connecting the upper roots of right and left auricles and downward by the back neck region. 5) A characteristic relation was observed to exist between the splitting lines and the hair streams in the skin in that the normal splitting lines were converted into irregular ones at the following parts of the skin ; the part where the hair stream disperses from the middle of the parietal region toward the periphery, the part where crossing of the hair streams takes place in the frontal region, and the part where the fan-like hair stream in the sacral region joins with the transversal hair stream of the vertebral region. 6) From histological point of view, the splitting lines of the skin discloses the splitting direction of relatively upper layer of the corium, whereas the direction taken by the hair streams is determined according to the slanting angles of the hair root. It was observed that the age change in the direction of the hair stream was determined by the direction or the growth orientation of the connective tissue fibers constituting the deeper layer of corium or the superficial layer of subcutaneous tissues in which the hair bulbs were rooted. This probably enplains why the splitting lines and the hair streams alternate their respective courses during the process of embryonic growth. As is outlined above. the splitting lines and the hair streams in the skin of human embryos undergo changes with age alternately, taking directions at one time similar, at another dissimilar to each other according to stages of the embryonic development. Thus the fact that the hari streams undergo changes with embrionic growth in close association with the splitting lines suggests that it also would display growth orientation of the skin, or more particularly, the growth orientation of the connective tissue constituting the deeper layer of corium or the superficial layer of subcutaneous tissue in the skin. It may be also said that the hair streams have close relation with the functional manifestation of the splitting lines in the skin in view of the confirmed specific relation existing between the irregular splitting lines and the hair streams.
- 九州歯科学会の論文