It becomes even more obvious when a piece of the roof of the archenteron is planted in the blastocoele.    From Wordnik.com.  [Hans Spemann - Nobel Lecture] Reference

Gastræa; they form the limits of the organism towards the exterior and towards the archenteron.    From Wordnik.com.  [Form and Function A Contribution to the History of Animal Morphology] Reference

They form the walls of a new cavity, the enterocoel, which is to be regarded as a nipped-off diverticulum of the archenteron.    From Wordnik.com.  [Form and Function A Contribution to the History of Animal Morphology] Reference

Tornaria (the larva of Balanoglossus) a similar formation of body-cavities by pouch-like outgrowths of the archenteron took place.    From Wordnik.com.  [Form and Function A Contribution to the History of Animal Morphology] Reference

Kowalevsky, in 1871, showed that the body-cavity of Sagitta was formed by a division of the archenteron into three parallel cavities, and in 1874 demonstrated the same fact for the Brachiopoda.    From Wordnik.com.  [Form and Function A Contribution to the History of Animal Morphology] Reference

They distinguished in the middle layer two quite distinct elements, the mesoblast proper, formed by the evagination of the walls of the archenteron, and the mesenchyme, formed by free cells budded off from the germ-layers.    From Wordnik.com.  [Form and Function A Contribution to the History of Animal Morphology] Reference

Its relation to the Coelom theory lies in the fact that Sedgwick regarded the segmentation of the body as moulded upon the segmentation of the mesoblast, which in its turn, as Kowalevsky and Hatschek had shown, was a consequence of its mode of origin as a series of pouches of the archenteron.    From Wordnik.com.  [Form and Function A Contribution to the History of Animal Morphology] Reference

Thus a portion of the upper marginal zone of the blastula or early gastrula, or else a piece of the roof of the archenteron of the mature gastrula was planted in the blastocoele of a young gastrula and so brought beneath the ectoderm from the beginning; it was demonstrated that these portions were able to induce neural plate.    From Wordnik.com.  [Hans Spemann - Nobel Lecture] Reference

In this last paper he described how the dark upper hemisphere of the frog's egg grows down over the lower white hemisphere and leaves free only the yolk plug; he observed the segmentation cavity and the archenteron, but thought that the former became the alimentary canal; he observed and interpreted rightly the formation of the medullary folds.    From Wordnik.com.  [Form and Function A Contribution to the History of Animal Morphology] Reference

Finally, we note two series of buds of cells, one on either side of the archenteron in Figure 7 ii.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

(Section 9) for invagination, nor to obliterate the archenteron and the blastopore through its pressure.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

The space ar. is the archenteron, the primordial intestine, and its mouth is called, the blastopore (bp.).    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

This stage is called the gastrula stage; ar. is the cavity of the gastrula, the archenteron; b.p. is its opening or blastopore.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

There is no open invagination of an archenteron in the fowl, as in the frog --, the gastrula, like the blastosphere, stage is also masked.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

Ishizuka Y, Minokawa T, Amemiya S (2001) Micromere descendants at the blastula stage are involved in normal archenteron formation in sea urchin embryos.    From Wordnik.com.  [PLoS Biology: New Articles] Reference

At the end of gastrulation, a small archenteron spreading dorsally from the blastopore represents the relatively small and superficial area of the egg where early embryonic axis formation occurs.    From Wordnik.com.  [BioMed Central - Latest articles] Reference

The relation of the two will be easily understood if we compare the fowl's archenteron to a glove-finger under pressure -- its cavity is obliterated -- and the frog's to the glove-finger blown out.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

Vegetal micromeres of the sea urchin embryo constitute a classic endomesoderm signaling center, whose potential to induce archenteron formation from presumptive ectoderm was demonstrated almost a century ago.    From Wordnik.com.  [PLoS Biology: New Articles] Reference

We naturally assume, from what we have learnt, that the next stages will be the formation of a hollow blastosphere, invagination, a gastrula forming mesoblast by hollow outgrowths from the archenteron, and so on.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

Since this Pmar1-responsive GRN potentially drives formation of a complete archenteron without detectable nuclear β-catenin, it is also conceivable that additional uncharacterized β-catenin-independent GRNs exist.    From Wordnik.com.  [PLoS Biology: New Articles] Reference

Reverting to Figure 7 ii., along the dorsal side of the archenteron a thickening of its wall appears, and is gradually pinched off from it to form a cellular rod, lying along under the nervous axis and above the intestine.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

Simultaneously, on either side of the notochord appear a series of solid masses of cells, derived mainly by cell division from the cells of the wall of the archenteron, and filling up and obliterating the segmentation cavity.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

Below the neural groove a thickening of the dorsal wall of the archenteron appears, and is pinched off to form a longitudinal rod, the precursor of the vertebral column, the notochord, shown in Figure 7 (n.c.), as imperfectly pinched off.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

By conceiving a gradually increasing amount of yolk in the hypoblastic cells in the ventral side of the archenteron, the substantial identity of the gastrula stage in the three types, which at first appear so strikingly different, will be perceived.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

This latter creature, like the gastrula, consists essentially of two layers of cells, an outer protective and sensory layer, and an inner digestive one; it has a primordial intestine, or archenteron, and its mouth is sometimes regarded as being a blastopore.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

Comparing the two gastrulas, it is not difficult to see that if we imagine the ventral wall of the archenteron of amphioxus to have its cells enormously enlarged through the mixing of yolk with their protoplasm, we should have a gastrula essentially like that of the frog.    From Wordnik.com.  [Text Book of Biology, Part 1: Vertebrata] Reference

My theory of the coelom as an enterocoel was accepted by Balfour and was greatly strengthened by his observations on the derivation of both notochord and mesoblastic somites from archenteron in the Elasmobranchs, and by the publication in 1877 by Kowalevsky of his second paper on the development of Amphioxus -- in which the actual condition which I had supposed to exist in the Vertebrata was shown to occur, namely, the formation of the mesoblast as paired pouches in which a narrow lumen exists, but is practically obliterated on the nipping-off of the pouch from the archenteron, after which process it opens out again as coelom "(pp. 16-18).    From Wordnik.com.  [Form and Function A Contribution to the History of Animal Morphology] Reference