. Journal of anatomy. t of the pre-oral gut usually known asSeessels pocket. It will be noticed that its distal extremity is continuouswith the prechordal plate, and we may therefore conclude that it hasarisen from that part of the fore-gut of the early stage of Perameles which The Development of the Hypophysis Cerebri, etc., in Marsupialia 191 is situated at the junction of the prechordal plate with the entoderm of thegut wall. The minute structure of the organs in this region is also worthy of thickened wall of the fore-gut immediately behind Rathkes pouchshows all the features char
. Journal of anatomy. t of the pre-oral gut usually known asSeessels pocket. It will be noticed that its distal extremity is continuouswith the prechordal plate, and we may therefore conclude that it hasarisen from that part of the fore-gut of the early stage of Perameles which The Development of the Hypophysis Cerebri, etc., in Marsupialia 191 is situated at the junction of the prechordal plate with the entoderm of thegut wall. The minute structure of the organs in this region is also worthy of thickened wall of the fore-gut immediately behind Rathkes pouchshows all the features characteristic of the protochordal plate of earlierstao-es, the granulation of the cells being recognisable here, and to a lessextent in the portion of oral plate adjacent to it. We may thereforeconclude that here, as in the previous stage, the antero-ventral wall of thefore-o-ut is formed by the protochordal plate. Seessels pocket, arising fromthe dorsal side of this portion of the gut (fig. 6, ), has no actual lumen. Fig. 7.—Stage IV. Peramdes msuta (13, VII, 05). Transver.^e sectionthrough primitive infundibular recess and Rathkes pouch. I., primitive infundibular recess ; , Rathlses pouch ; V., blood-vessel. but is obviously tubular in structure, its walls consisting of a very regularepithelium. It is impossible to define exactly the limit between the wall ofSeessels pocket and the prechordal plate (), which consists of a ratherirregular mass of cells, containing darkly staining granules. From itsmargin, cells here and there project, giving it an irregular outline, in whichrespect it contrasts with the notochord proper, whose outline is perfectlydefinite. Some of these cells appear to represent traces of the formerconnection between the prechordal plate and the premandibular .somites,which have now acquired a considerable size and possess a distinct this stage they have already been described and figured by Eraser (12). The walls of Rathkes pouch (fig. 7
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectanatomy, bookyear1867
