. The elements of Embryology,. CHAP. IV.] THE CEREBRAL VESICLES. 59. An Embrto Chick of the fiest dat (about thirtt-six hours) viewed fkom below as a transparent object. ]il. Outline of the pellucid area. FB. The forebrain or first cerebral vesicle, projecting from the sides of which are seen the optic vesicles op. A definite head is now constituted, tlie backward limit of the somatopleure fold being indicated by the faint line S. 0. Around the head are seen the two limbs of tlie amniotic head- fuld : one, the true amnion a, closely enveloping the head, the other, the false amnion a', at some
. The elements of Embryology,. CHAP. IV.] THE CEREBRAL VESICLES. 59. An Embrto Chick of the fiest dat (about thirtt-six hours) viewed fkom below as a transparent object. ]il. Outline of the pellucid area. FB. The forebrain or first cerebral vesicle, projecting from the sides of which are seen the optic vesicles op. A definite head is now constituted, tlie backward limit of the somatopleure fold being indicated by the faint line S. 0. Around the head are seen the two limbs of tlie amniotic head- fuld : one, the true amnion a, closely enveloping the head, the other, the false amnion a', at some distance from it. The head is seen to project beyond the anterior limit of the pellucid area. The splanchnopleure fold extends as far back as sp. Along its diverging limbs are seen the conspicuous venous roots or omphalo-mesaraic veins, uniting to form the heart A, which continuing forward as the bulbus arteriosus ha, is lost in the substance of head just in front of the somatopieure fold. Lying (in this position of the embryo) under the heart is seen the broad foregut d, the wide crescentic opening into which at the hind limit of the splanchnopleure fold is very conspicuous. Beneath the foregut are faintly seen the hind brain HB. and higher up and more distinctly the mid brain MB. These are not yet completely differentiated, and their limits are in consequence very obscurely Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Foster, Michael. London : Macmillan
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherlondo, bookyear1874
