Multicellular Construction

Most multicellular organisms exploit mechanoreceptors — specialized cells that detect external mechanical forces — to help construct their internal view of the external world. The senses of hearing, balance and touch all rely on mechanoreceptors, as do the proprioceptive sensations that tell an organism how it is situated in the environment. Mechanoreception is probably one of the most ancient of the senses. 

The significance of exon shuffling to protein evolution, in particular in respect to the development of multicellularity, is signified by a short inventory of processes involving proteins created by modular assembly. Exon shuffling facilitates the construction of proteins involved in regulation of blood coagulation, fibrinolysis, and complement activation, plus most constituents of the extracellular matrix, cell adhesion proteins, and receptor proteins [10, 57]. 

A plurality of multicellular bodies can be arranged in a pattern and allowed to fuse to form an engineered tissue (37). Such three-dimensional constructs can be assembled by printing the multiceUular bodies and filler bodies. 

Poraver, Expanded glass multicellular spheres, Construction Technology Div. 

Bone and soft tissues are complex multicellular structures requiring oxygen, nutrients, and cell signaling cues to allow cells to form functional tissues. The oxygen diffusion limit of 150 iim [100] limits the size of in vitro TE constructs without vascularization. Often coculture is employed to promote prevascularization of the TE graft (reviewed in [101]). 

One type of 3D systems is based on the guided self-formation of multicellular spheroids. Such spheroids have been used primarily with liver and renal cells. One example of the use of such cultures is the study of gliadin toxicity [Elli et al, 2003]. In addition, Goodwin et al. [2000] have constructed a 3D model for assessment of in vitro toxicity in Balaena mysticetus renal tissue. 

Retracing the transition from prokaryotes to eukaryotes an abrupt change produced a cell structure which, after a slow beginning during the period of protists, led to the construction of multicellular organisms. From then on, at least in the eyes of the observing... 

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