Anteroposterior patterning

Segmental Patterning and Cell Fate Determination in the Mesoderm 

It is conceivable that mesodermal A and P domains do not function as compartments in their entirety, but rather as discrete units of gene expression. Perhaps compartmental units are only formed as individual mesodermal tissues start to segregate within each domain and precursors of different tissues become distinct from each other. In this case, each A and P domain would be composed of several different compartments along its dorsoventral extent during stage 11. 

Many of the segmentation genes that determine the periodic subdivisions of the ectoderm are also involved in generating the mesodermal A and P domains, as well as in the resulting diversification of tissues in the trunk mesoderm. For example, mutations in pair-rule genes that reduce the number of ectodermal parasegments in half also produce half the number of mesodermal parasegments. Notably, null mutations 

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Lowe CJ, Wu M, Salic A, Evans L, Lander E, Stange-Thomann N, Gruber CE, Gerhart J, Kirschner M (2003) Anteroposterior patterning in hemichordates and the origins of the chordate nervous system. CeU 113 853-865... 

Ch ng, Q., Kenyon, C. 1999. egl-27 generates anteroposterior patterns of cell fusion in C. elegans by regulating Hox gene expression and Hox protein function. Development 126, 3303-3312. 

Isaacs, H.V., Andreazzoli, M., Slack, J.M. 1999. Anteroposterior patterning by mutual repression of orthodenticle and caudal-type transcription factors. Evolution and Development 1, 143-152. 

Yang, Y. and Niswander, L. (1995) Interaction between the signalling molecules WNT and SHH during vertebrate Umb development dorsal signals regulate anteroposterior patterning. Cell 80,939-947. 

Doniach, T., PhiUips, C. R., and Gerhart, J. C. (1992) Planar induction of anteroposterior pattern in the developing central nervous system of Xenopus laevis. Science 257,542-545. 

Sirbu, I. O., X. L. Zhao, and G. Duester. 2008. Retinoic Acid Controls Heart Anteroposterior Patterning by Down-Regulating Ml Through the Fgf8 Pathway. Dev Dynam 237, no 6 1627-35. 

Zoltewicz, J.S., Gerhart, J.C. 1997. The Spemann organizer of Xenopus is patterned along its anteroposterior axis at the earliest gastrula stage. Dev. Biol. 192, 482-491. 

Gradients of transcription factors, produced from maternal mRNAs in the early Drosophila embryo, control the patterned expression of embryonic genes, leading to segmentation of the embryo along the anteroposterior axis. 

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