Time and the appearance of cartilage centers in human embryos with special reference to its individual differences
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- Tanaka Osamu
- Department of Anatomy, Faculty of Medicine Kyoto University
書誌事項
- タイトル別名
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- Time of the Appearance of Cartilage Centers in Human Embryos with Special Reference to its Individual Difference
- Time of the appearance of cartilage centers in human embryos with special reference to individual difference
この論文をさがす
説明
Methylene blue clearance p reparations of 422 externally normal embryos were examined for study of individual difference in chondrification. These human embryos, at stages ranging from 13 to 23 of Streeter's horizon (5.1 to 30.5 mm crown-rump length), that is, at five to eight weeks postconceptional age, were obtained from healthy pregnant women subjected to induced abortion by curettage. The stage of the onset of cartilage centers w hich appear in 100% by horizon 23, will be mentioned in the sequence of the stage of the first appearance: The cartilage centers of the humerus appear between horizons 16 and 18. Those of the 1st ribs, vertebral bodies, radius, ulna, and metacarpals appear between horizons 16 and 19. Those of the presacral vertebral arches, scapula, carpals, proximal phalanges of the hand and pelvis appear between horizons 16 and 21. Those of the metatarsals appear between horizons 16 and 22. Those of the 2nd-6th ribs, femur, and tibia appear between horizons 17 and 19. Those of the 7th-9th ribs and fibula appear between horizons 17 and 20. Those of the 10th-11th ribs appear between horizons 17 and 21, and the 12th ribs between horizons 17 and 22. Those of the proximal phalanges of the foot and calcaneus appear between horizons 17 and 23. Those of the Meckel's cartilage appear between horizons 18 and 22, and of the tarsus between horizons 18 and 23. Next, the stage of the first appearance of the cartilage centers which appear only occasionally by horizon 23 will be given as follows : the occipital arch and distal phalanges of the hand, 16 ; the middle and distal phalanges of the foot, 17 ; the squamous of the occipital, 18 ; the malleus, styloid process, temporal (greater) wing of sphenoid, nasal, and cricoid, 19 ; the supraoccipital, 21. The above mentioned data differ somewhat from the findings of the previous investigators. Moreover, 37 embryos with asymmetry, regarding the appearance of some cartilage centers of bilateral pair were found. The incidence of the 7th cervical rib was 7% in horizon 19, 32% in horizon 20, 37% in horizon 21, 34% in horizon 22, and 30% in horizon 23. The 7th cervical ribs, when present, were usually bilateral. The lumbar rib (unilateral or bilateral) was observed on the incidence betweeen 4% and 7% at horizons from 19 to 23.
収録刊行物
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- Okajimas Folia Anatomica Japonica
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Okajimas Folia Anatomica Japonica 53 (4), 173-197, 1976
Editorial Board of Okajimas Folia Anatomica Japonica