. Journal of anatomy. plate, fig. U, ) is nowdistinctly thickened and has a very characteristic appearance. The cellsare regularly arranged, contain a number of darkly staining granules, andare vacuolated. The first trace of the primordium of the hypophysis is now anterior to the oral plate, the ectoderm consists of distinctlyelongated epithelial cells () The thickening extends forwards as far 194 Dr Katharine M. Parker as the optic recess, and is most marked at the point of contact of theectoderm witli the entoderm of the pre-oral gut. Posterior to this point
. Journal of anatomy. plate, fig. U, ) is nowdistinctly thickened and has a very characteristic appearance. The cellsare regularly arranged, contain a number of darkly staining granules, andare vacuolated. The first trace of the primordium of the hypophysis is now anterior to the oral plate, the ectoderm consists of distinctlyelongated epithelial cells () The thickening extends forwards as far 194 Dr Katharine M. Parker as the optic recess, and is most marked at the point of contact of theectoderm witli the entoderm of the pre-oral gut. Posterior to this pointthe modified ectoderm of the hypophj^sis thins out slightly and is directlycontinuous with the oral plate (), in which the ectoderm and entodermare now indistinguishable. In transverse section we can see the primordium of the hypophysis asa thickened and slightly invaginated stretch of ectoderm, in intimatecontact with the floor of the brain. Stage III. Basyuruf>lviuerrinu^ (II., a, 01): Embryos a, h, and c.—. Flu. 10. — Stage III. JJasyiirus vivcrrinus(II., o, 01). Embryo a. Median longi-tudinal section through the hypo})hysisand Seessels pocket. SI. 2-3—7. Fig, 11.—Stage III. Dasyurus viverrimis {\\., a,01). Embryo r. Median longitudinal sectionthrough the hvjiophysis and Seessels 2-1-11. , fore-gut; , hypophysial epithelium: I., primitive infundibuhu- recess; M., meseiichyme ;, optic groove; , oral plate; (?), possible trace of premandibular somite; ,Rathkes pouch ; , Seessels pocket. The embryos of this stage are only slightly more advanced than those ofthe preceding. The optic groove (fig. 10, ) and the infundibular recess(I.) are slightly more clearly marked. The hypophysis has distinctlydeepened and the oral plate has ruptured. The relations to the pre-oralgut in individual embryos of the stage vary slightly (cf. figs. 10 and 11). In two embryos {a and b, fig. 10), which are cut longitudinally, thehypophysis is s
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectanatomy, bookyear1867
