Pore canals

We can describe the system of fruit with the amount (percentage)of the space which is not filled with material. There are pores, canals and holes between the fruits. This is called porosity. 

Figure 23. Aquaporin, water-channel protein, (a) End-on view of the pore from extracellular surface, (b) side-view of the pore-canal, (c) six membrane spanning helices of the aquaporin monomer. The asparagine-proline-alanine (NPA) motifs in the second and fifth loops fold in to produce the water channel.

The crustacean cuticle is made of chitin and protein and has an outer tanned epicuticle within which lies a tanned and calcified exocuticle. The thickest layer is the inner endocuticle which is heavily calcified but contains no tanned problems. The inside of the exoskeleton is formed by a membranous layer which is neither tanned nor mineralized but which covers the cellular epidermis. This layer contains a variety of cell types including melanophores and epidermal cells but the secretion of the exoskeleton is mainly performed by the cuticle-secreting cells and the associated intra-epidermal or reserve cells. The exoskeleton is penetrated by tegumental ducts and by pore canals. The first of these carry secretions from glands through the thickness of the cuticle while the latter may consist of 50—90 fine protoplasmic extensions of each cuticle-secreting cell penetrating the exoskeleton at a density of about 4 X 10 pore canals mm". ... 

The displacement of liquids is strongly affected by surface properties of the system crude oil-water-rocks. With increases in temperature, surface properties of both the formation rocks and the formation liquids change. When water is injected into the formation, some of the surface-active substances of the crude dissolve in the water. This dissolution brings about a reduction in surface tension at the phase boundary. Selective wetting of the surfaces of capillary pores with water is also improved. The surface-acdve molecules of oil form a layer that is adsorbed on the surfaces of pore canals. When the temperature is increased, the thickness of this layer is reduced, which, in turn, leads to an increase in permeability of the formation. 

Dentine is a tissue unique to vertebrates and its presence in Anatolepis confirms the vertebrate affinity of the taxon. An arthropod affinity can be ruled out since arthropod cuticle does not possess canals which radiate from a single large central cavity— arthropod pore canals are single, discrete structures, oriented perpendicularly to the outer surface of the cuticle and which penetrate the full whole thickness of the hard tissue. 

Thomson, K.S. (1977) On the individual history of cosmine and a possible electroreceptive function of the pore-canal system in fossil fishes , in Andrews, S.M., Miles, R.S. and Walker, A.D. (eds) Problems in vertebrate evolution, Linnean Society Symposium Series, 4, London Academic Press, pp. 247-71. 

Enamel lining of pore canals absent (0) present (1). 

Shape of pore-canal funnel-shaped (0) flask-shaped (1). 

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