. The Journal of comparative neurology and psychology. Fig. 10. Squalus ac, 2G somites, frontal section, inf., the so-called infun-(libulum. pressed down to meet the ectoderm. In Fig. 8 the origin of thisfrom the neuropore is strongly suggested, especially as the spotmarked neurop. is at the upper border of the lamina distance dorsal to the extreme point to which the preoral ento-derm or premandibular mesoderm ever reaches. In Dr. Nealspreparations which I have studied the entoderm has a differenttone from the other tissues and there is a decided difference in theform of the ce
. The Journal of comparative neurology and psychology. Fig. 10. Squalus ac, 2G somites, frontal section, inf., the so-called infun-(libulum. pressed down to meet the ectoderm. In Fig. 8 the origin of thisfrom the neuropore is strongly suggested, especially as the spotmarked neurop. is at the upper border of the lamina distance dorsal to the extreme point to which the preoral ento-derm or premandibular mesoderm ever reaches. In Dr. Nealspreparations which I have studied the entoderm has a differenttone from the other tissues and there is a decided difference in theform of the cells and in the size of the nuclei between the preman-dibular mesoderm and the terminal neural crest mesectoderm. In embryos of 29 and 30 somites (Figs. 11 and 12) premandibular Johnston, Forehrain Vesicle in Vertebrates. 475 and anterior head cavities are small, sejDarate from each other, butboth connected with the median mass which is crowded behind theinfundibnlnm. The median band connecting- the anterior cavities. j md Fig. 11. Squalus ac, 30 somites, frontal section through premandibular andanterior head cavities, x 150. is small and disappears at this stage. The premandibular somitesretain the connection with the median mass in which cavities appearin later stages and finally fuse with the cavities of the premandib-ular somites as fully described by l^eal and others. The anterior 47^ Journal of Comparative Neurology and Psychology. cavities extend forward at the sides of the infundibular region inthe position in which they were first described by Miss Piatt. Ex-cept where they are in contact with the premandibular somite the
Size: 1497px × 1668px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorwistarinstituteofanat, bookcentury1900, bookdecade1900
