人胎児腸管の発生学的研究

Abstract

1. The pharyngeal pouches contact widely with the skin ectoderm and remain simple till the Streeter's horizon XV stage.2. During the next horizon XVI stage the contact areas becoming smaller surrounded by the mesenchymal mass form 3 pairs of small cervical vesicles corresponding to the 2nd, 3rd and 4th cervical grooves. The 4th cervical groove is the smallest and disappears during the XVI stage, while the 2nd and 3rd are visible in the next XVII stage passing away the former earlier, the latter the largest a little later.3. During these changes of the external forms the internal pharyngeal pouches begin to form the ductless glands. From the 3rd pouches begin to differentiate the parathyreoids 3 and the thymus, from the 4th the parathyreoids 4 and the lateral thyreoids. When these glands appear in form, these pouches are shut off from the cavity of the primive pharynx.4. This differentiation of these ductless glands indicates that it begins a little later than the Streeter's assertion. After the latter's description begins this differentiation in the XIV stage while our material late in the XVI.5. The oesophagus and trachea are embeded in the back body wall till our latest stage of XVIII, although the differentiation of the tissue is proceeding.6. As the stomach deviates to the left, there appears mesogastrium dorsale enclosing the cavity of the bursa omentalis with the dorso-caudal surface of the stomach. After Streeter the pouch for bursa omentalis appears in the horizon XII stage. In our material of the XIV stage the deviation of the stomach is so much advanced that the mesogastrium dorsale and ventrale are distinct.7. The mesoduodenum dorsale becomes evident as “Pancreaswulst” at the site of the dorsal mesentery continuous with the dorsal and ventral mesogastrium in the XVI stage, in which the site of the dorsal and ventral pancreas becomes definite dorsal to the duodenum. Its tissue is becoming massiv through the XVII to XVIII stage that at the latter stage it encloses the distal part of the duodenum close to the right side of the mesocolon.8. After Streeter a definitive mesentery beginning near the caudal end of the duodenum and extending downward to include the upper half of the colon can be spoken first in the XVI stage, but in our material a thin mesentery is visible already in the XIV stage without formation of a intestinal loop, the swelling of caecum also visible in this stage.9. The formation of a intestinal loop begins in the XV stage, which protrudes straight through XVI, XVII stages till about 3mm long, then appear in the XVIII stage curvatures at the cranial half of the loop. In the XVI stage begins the formation of the appendix.