Mesoderm

Candia, A. F., Hu, J Crosby, J Lalley, R A., Noclen, D Nadeau, J., and Wright, C. V. E (1992). Mox-1 and Mox-2 define a novel homeobox gene subfamily and are differentially expressed during early mesodermal patterning in mouse embryos. Development 116 1123-1136. 

Cseijesi, P., Lilly, B., Bryson, L., Wang, Y Sassoon, D., and Olson, E. (1992). MHox a mesodermally restricted homeodomain protein that binds an essential site in the muscle creatine kinase enhancer. Development 115 1087-1101. 

Kress, C., Vogels, R DeGraff, W Bonnerot, C., Meijlink, F and Deschamps, J. (1990). Hox 2.3 upstream sequences mediate lacZ expression in intermediate mesoderm derivatives of transgenic mice. Development 109 775-786. 

Mayer, T. C., and Fishbane, J. L. (1972). Mesoderm-ectoderm interaction in the production of the agouti pigmentation pattern in mice. Genetics 71 297-303. 

Chia It is not clear that it is the exact same complex present in the mesoderm. We know Insc is present in the mesoderm progenitors, but there is no indication of Baz. Perhaps components of this complex are involved. 

Nurse If they were, there wouldn t be a polarized asymmetry in that system, it would simply be asymmetry. Therefore the role of Insc might be better thought of in terms of generating asymmetry in response to no polarity in the mesoderm, but in this system in response to another polarity. 

Raff What about the asymmetric divisions in the mesoderm Where is the cell polarity originating ... 

Chia The ones we know of are Insc and Numb. We don t think that Baz is expressed in the mesoderm. 

The best examples of pleiotropy have been provided by developmental biologists. Two examples illustrate the pleiotropic action of developmental genes. Sonic hedgehog participates in the formation of the different cell types that form the neural tube, in limb development and in somitogenesis, a process by which mesodermic cells aggregate to form bones and muscles. 

Ensini, M., Tsuchida, T. M., Belting, H.-G. and Jessell, T. M. The control of rostrocaudal pattern in the developing spinal cord specification of motor neuron subtype identity is initiated by signals from paraxial mesoderm. Development 125 969-982,1998. 

The FGFs stimulate the proliferation of mesodermally and ectodermally-derived cells and play central roles in mammalian development. Members of the FGF family are expressed in the embryonic period and are required for several critical events in neural development and specifically for neural induction. FGF-8 is necessary for positional identity required for axial specification and patterning of limb development. FGF-2 stimulates the proliferation of multipotential stem cells that subsequently give rise to neurons of the cortex and other brain regions. 

Wong,P. C.,Zheng,H.,Chen,H. etal. Presenilin 1 is required for Notchl and Dill expression in the paraxial mesoderm. Nature 387 288-292,1997. 

Rollins-Smith, L.A., and Blair, P., Contribution of ventral blood island mesoderm to hematopoiesis inpostmetamorphic and metamorphosis-inhibited Xenopus laevis, Dev. Biol., 142, 178, 1990. 

The cerebral endothelial cells of the blood-brain barrier originate from the middle germinal sheet of the embryo, the mesoderm [17]. Concomitant with migration and proliferation of capillary endothelial cells during formation of the cerebral vascular network occurs the imprinting of the cells. Thereby, induction by the cellular surrounding plays an important role [18-21], The relevance of the cellular environment for the development of the barrier function of cerebral microvessels was first demonstrated by Stewart and Wiley [22], who transplanted embryonic brain tissue of a quail into embryonic gut tissue of chicken and vice versa. The cerebral transplant was vascularized by intestinal vessels, in which properties of the blood-brain barrier had been induced. In transplanted brain vessels, however, no characteristics of a barrier could be demonstrated, due to the lack of a neuronal environment. These results indicated that the cerebral microvessels are of extraneuronal origin, with properties that are induced by the cellular environment. In addition, brain tissue has the capability to induce blood-brain barrier characteristics also in noncerebral vascular tissue [23],... 

Steinbach OC, Wolffe AP, Rupp RA (1997) Somatic linker histones cause loss of mesodermal competence in Xenopus. Nature 389 395-399... 

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