Spatial relationship between endophyll, primordial germ cells, sickle endoblast and upper layer in cultured avian blastoderms

Callebaut, M.; Nueten, Emmy Van; Bortier, Hilde; Harrisson, F.; Nassauw, Luc Van; Schrevens, A.

doi:10.1051/rnd:19970305

Cited by 8 publications

(13 citation statements)

References 3 publications

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“…Instead of Petri dishes, the culture vessels described by Gaillard [17] figure 7D). In the sections, the much thickened quail upper layer (with a preneural plate-like aspect) was seen to be partially recurved at its rims and enclosed the endophyll ( figure 7E, F) [10][11][12]. This seems to be in agreement with studies from Settle [22] and Zagris [24] figure 211A and IIB).…”

Section: Introductionsupporting

confidence: 88%

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Interaction of central subgerminal ooplasm with the elementary tissues (endophyll, Rauber's sickle and upper layer) of unincubated avian blastoderms in culture

Callebaut¹,

Nueten²,

Bortier³

et al. 1999

Reprod. Nutr. Dev.

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Section: Introductionsupporting

confidence: 88%

“…Recent studies [5,6,8,12,13] have yielded new data concerning the structures and developmental events in avian intrauterine germs after bilateral symmetrisation and in unincubated eggs. The terminology [ 13] for the different components of an unincubated quail blastoderm and surrounding structures is represented in figure 1.…”

Section: Introductionmentioning

confidence: 99%

Interaction of central subgerminal ooplasm with the elementary tissues (endophyll, Rauber's sickle and upper layer) of unincubated avian blastoderms in culture

Callebaut¹,

Nueten²,

Bortier³

et al. 1999

Reprod. Nutr. Dev.

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“…The different components of an unincubated avian blastoderm are shown in Figure 1. We have shown by the use of the quail-chicken chimera technique that during early incubation Rauber's sickle differentiates into: 1) junctional endoblast by local proliferation of its cells into the neighboring subgerminal ooplasm, and 2) sickle endoblast by centripetal and cranial growth, forming a one-cellthick layer (Callebaut and Van Nueten, 1994;Callebaut et al, 1997b). Our previous studies indicated that the main function (i.e., mesoblast and definitive endoderm induction in the upper layer) of Rauber's sickle in avian blastoderms is homologous with the function of Nieuwkoop's center (Nieuwkoop, 1969(Nieuwkoop, , 1973 in amphibian blastulas.…”

mentioning

confidence: 99%

Positional information by rauber's sickle and a new look at the mechanisms of primitive streak initiation in avian blastoderms

Callebaut¹,

Nueten²,

Bortier³

et al. 2003

Journal of Morphology

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The present experimental in vitro study suggests that a primitive streak (PS) in avian blastoderms is induced by diffusion of morphogenetic substances emanating from Rauber's sickle. Indeed, even without direct contact between a quail Rauber's sickle and the reacting upper layer (by interposition of a vitelline membrane), a PS can be induced in the isolated area centralis or antisickle region of unincubated chicken blastoderms. The so-formed PSs are localized below the vitelline membrane in the immediate neighborhood of the apposed Rauber's sickle material. This seems to indicate that Rauber's sickle organizes the formation of the avian PS according to the basic concept of "positional information." The morphogenetic substances seem to have an effect only on the formation of a PS. Each part of Rauber's sickle seems to have, point by point, the same thickening and PS-inducing effect on each corresponding part of the underlying upper layer (UL). By a mechanism of sliding over the basement membrane and fusion, this finally results in the formation of one single median PS. Our study shows that a PS can be induced in the total absence of hypoblast (sickle endoblast) or caudal marginal zone, by only the presence of Rauber's sickle material. In contrast, the differentiation of mesoblast into blood islands under the influence of Rauber's sickle and neural tissue development are impaired by the interposition of a vitelline membrane. The latter could be due to the absence of a normal interaction of Rauber's sickle-derived sickle endoblast with endophyll and/or upper layer and the absence of cranial migration of the mesoblast. Thus, earlier studies and the present study indicate the existence of a temporospatially bound cascade of gastrulation and neurulation phenomena and blood island formation in the avian blastoderm, starting from Rauber's sickle, the primary major organizer with inducing, inhibiting, and dominating potencies. The latter not only plays a role by secretion of signaling molecules, but also influences development by its cell lineages (junctional endoblast and sickle endoblast).

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“…In both types of the present experiments there seems thus to exist a common link between the observed induction phenomena: the presence of ␦ ooplasm in the involved deep structures. Indeed, the nucleus of Pander contains ␦ ooplasm as well as the structures derived from it: i.e., endophyll with associated primordial germ cells (Callebaut, 1987;Callebaut et al, 1997) and (in the present study) sickle endoblast derived cells after colonization of the neighboring ooplasm. In the experiments in which sickle endoblast was interposed between a central subgerminal ooplasmic mass and the isolated antisickle region, two kinds of reactions were observed.…”

Section: Discussionmentioning

confidence: 53%

Induction and improved embryonic development by the nucleus of pander in associated avian blastoderm parts: Influence of δ or γ ooplasm

Callebaut

Nueten

Harrisson

et al. 2004

Journal of Morphology

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After placing in vitro, central subgerminal ooplasm (containing a central nucleus of Pander) from a quail germ disc of a prelaid egg (before symmetrization) on the upper layer of an isolated chicken antisickle, we observed the induction of a radially oriented preneural plate (without interference of chordamesoblast). This observation suggests the primary existence during the period of symmetrization in utero of an until now unknown temporospatially linked "vertical" effect, emanating from the nucleus of Pander, on the parallel (pre)neural plate anlage forming part of the area centralis in the overlying blastoderm. For comparison, we "sandwiched" in vitro a quail sickle endoblast fragment between the deep side of the upper layer of an isolated chicken antisickle region and a central subgerminal ooplasmic mass. This resulted in a colonization of the subgerminal ooplasmic mass by quail sickle endoblast cells followed by improved neurulation and/or gastrulation phenomena. The latter never occurs in the absence of central subgerminal ooplasm. In both types of experiments there seems to exist a common link between the observed induction phenomena: the presence of delta ooplasm in the involved deep structures. Indeed, the nucleus of Pander contains delta ooplasm as well as the structures derived from it, i.e., endophyll with primordial germ cells and sickle endoblast-derived cells after colonization of the neighboring central ooplasm (present study). Therefore, we think that the preneural plate-inducing effect observed after placing a nucleus of Pander on the antisickle region is due to the presence of a factor in the delta ooplasm that diffuses in the neighborhood. The appearance of gastrulation phenomena in the second type of experiment seems to be due to colonization of the more peripheral part of the central subgerminal ooplasm containing the more superficial and peripheral gamma ooplasm in which Rauber's sickle material can develop. This suggests that the kind of involved ooplasm (delta or gamma) can predetermine the inductive activity of the deep structures that contain it: the central part of the nucleus of Pander and/or endophyll for preneurulation phenomena and sickle endoblast (in the presence of central subgerminal ooplasm) for gastrulation and/or neurulation phenomena.

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Spatial relationship between endophyll, primordial germ cells, sickle endoblast and upper layer in cultured avian blastoderms

Cited by 8 publications

References 3 publications

Interaction of central subgerminal ooplasm with the elementary tissues (endophyll, Rauber's sickle and upper layer) of unincubated avian blastoderms in culture

Interaction of central subgerminal ooplasm with the elementary tissues (endophyll, Rauber's sickle and upper layer) of unincubated avian blastoderms in culture

Positional information by rauber's sickle and a new look at the mechanisms of primitive streak initiation in avian blastoderms

Induction and improved embryonic development by the nucleus of pander in associated avian blastoderm parts: Influence of δ or γ ooplasm

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