. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. ORGANIZATION AND DEVELOPMENT OF ANIMALS IN GENERAL. 37 N 2. The tissues of the connective substance. Under this term there are included a great number of different tissues which morpho- logically resemble each other in the presence of a greater or less amount of intercellular substance, intercalated between the cells (con- nective tissue corpuscles). They connect and surround other tissues, and serve as supporting and skeletal structures. The intercellular substance arises from the cells as
. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. ORGANIZATION AND DEVELOPMENT OF ANIMALS IN GENERAL. 37 N 2. The tissues of the connective substance. Under this term there are included a great number of different tissues which morpho- logically resemble each other in the presence of a greater or less amount of intercellular substance, intercalated between the cells (con- nective tissue corpuscles). They connect and surround other tissues, and serve as supporting and skeletal structures. The intercellular substance arises from the cells as a differentiation of the peripheral part of their protoplasm; it cannot accordingly be genetically clearly distinguished from, the cell membrane and its differentiations, which we have considered in connection with epithelial tissue. The cell walls already produced by the protoplasm may also become fused with the intercellular substance, and so contribute to its increase. The intercellular substance is usually secreted by the whole periphery of the cell, and presents great variations both in its morphological and chemical characters. When the amount of intercellular substance is small, the tissue is called cellular or vesicular connective tissue. This form is found especially in medusae, molluscs, and worms, and to a less extent in verte- brates (notochord, fig. 25), and is not sharply marked off from cartilaginous tissue. Embryonic connective tissue, which consists of closely aggregated embryonic cells, evidently closely re- sembles it. Mucous or gelatinous connective tissue is characterised by possessing a watery hyaline and gelatinous matrix. The condition of the cells in each case is different. Frequently they send out delicate, often branched processes which anastomose with one another and form a network. In addition, however, parts of the intercellular substance may be differentiated into bundles of fibres (Wharton's gelatine in the umbilical cord). Such forms of tissue
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