. The anatomical record. Anatomy; Anatomy. VASCULAKIZATIOX PHENOMENA 337 a total period of forty-eight hours (figs. 8, 9 and 10). No at- tempt will be made at present to set forth the processes which inter\-ene l^etween the stages of thirty-two and fortv-eight hours. The ]:)roanmion (fig. 8), a region normally devoid of meso- derm, contains a rounded jiouch which is continuous anteriorly with the extra-embryonic coelom. The cut edges of the ectoder- mal and entodermal layers of the proamnion have fused forming a blind sac around the enclosed coelomic pouch; likewise the cut. Fig. S .Section th
. The anatomical record. Anatomy; Anatomy. VASCULAKIZATIOX PHENOMENA 337 a total period of forty-eight hours (figs. 8, 9 and 10). No at- tempt will be made at present to set forth the processes which inter\-ene l^etween the stages of thirty-two and fortv-eight hours. The ]:)roanmion (fig. 8), a region normally devoid of meso- derm, contains a rounded jiouch which is continuous anteriorly with the extra-embryonic coelom. The cut edges of the ectoder- mal and entodermal layers of the proamnion have fused forming a blind sac around the enclosed coelomic pouch; likewise the cut. Fig. S .Section throiigli the t'orebrain of a hcad-merophist .showing a pro- ainn'otic sac containing a pouch of coelomic mesothelitna. On the ventral side of the sac is a peculiar proliferation of entodermal cells very constanth' ap])eur- ing in experiments of this type, generally more symmeti'ically situated. Total incubation, forty-eight hours. Operation v\ the time of the second intersomitic groove (;< 55). , Type IT, no. 3 r, coelom; e. forebrain; C, ectoderm; f/, entoderm; J, extra-embryonic vessels. edges of the once continuous blastoderm have fused. On the ventral surface of the proamniotic sac will be noticed an ento- dermal thickening, in appearance not unlike an in\'erted nem-al groove. This structm'e is quite constant in experiments of this type. I would interpret it as a cell-complex representing potentially the floor of the fore-gut in case of normal infolding. The transverse incision in this experiment was made some dis- tance behind the site of the anterior intestinal portal, so that there projected behind the posterior extent of the proamniotic. 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 Bardeen, Charles Russell, 1871-1935, ed; Boyden, Edward A. (Edward Allen), 1886-1976; Bremer, John Lewis
Size: 2280px × 1096px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectanatomy, bookyear1906
