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A sticky problem: The Xenopus cement gland as a paradigm for anteroposterior patterning
Author(s) -
Sive Hazel,
Bradley Leila
Publication year - 1996
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/(sici)1097-0177(199603)205:3<265::aid-aja7>3.0.co;2-g
Subject(s) - ectoderm , biology , noggin , microbiology and biotechnology , mesoderm , endoderm , bone morphogenetic protein 4 , sonic hedgehog , anatomy , endocrinology , bone morphogenetic protein , embryonic stem cell , medicine , embryo , embryogenesis , genetics , signal transduction , gene
The cement gland is a mucus‐secreting organ found at the extreme anterior of frog embryos.It attaches the embryo to a solid support before swimming and feeding begin, and also serves arelated sensory function that stops the embryo from moving once it is attached. Cement gland isan extremely useful anterior marker, whose study continues to yield fundamental informationconcerning vertebrate axial patterning. Cement gland arises from the outer layer of the embryonicectoderm and, in Xenopus, forms a cone of columnar epithelium. It is the first ectodermal organto differentiate, beginning to do so by late gastrula. A battery of genes expressed in thedeveloping and mature cement gland serve as useful markers. Cement gland development can beinfluenced by both stimulatory and inhibitory cell interactions. Stimulatory signals arise from theanterior neural plate, head endoderm, and the dorsal mesoderm. Inhibitory signals are present inthe posterior dorsal mesoderm and in ventral ectoderm and mesoderm. Further, signalling betweenthe ectodermal layers may restrict cement gland differentiation to the outer ectodermal cells.Several secreted molecules are able to induce or repress cement gland formation: these includenoggin, follistatin, hedgehog, chordin, retinoic acid, embryonic fibroblast growth factor (eFGF),Bone Morphogenetic Protein‐4 (BMP‐4), and Xwnt‐8. Several of these factors alter expressionof the homeodomain gene Xotx2, which may be a transcriptional activator of cementgland differentiation genes. The significance of the cell interactions and factors described inpositioning cement gland at the front of the embryo is explored. © 1996 Wiley‐Liss,Inc.