74 



HUMAN ANATOMY. 



tissues are usually described as of two kinds, — the fixed or connective-tissue cells 

 proper, and the migratory or wanderi7ig cells. The latter, while frequently included 

 among the elements of these tissues, are usually only migratory leucocytes which 

 temporarily occupy the lymphatic clefts within the connective substance. 



Fig. 94. 



Fig. 95. 



Young- connective-tissue cells 

 from subcutaneous tissue of cat 

 embryo. X 590. 



Granule-cells (mast-cells) from submucous tissue of mouth. X looo- 

 z/, V, sections of blood-vessels. 



Fixed 

 cells 



The typical connective-tissue cell, in its younger condition, possesses a flattened, 

 plate-like body from which branched processes extend. With the completed growth 



of the tissue, the expanded, 

 Fig. 96. often irregularly stellate, 



element contracts to the 

 inconspicuous spindle cell 

 commonly observed in adult 

 areolar tissue. 



Gramde-cells are addi- 

 tional elements occasionally 

 encountered in connective 

 tissues. They are irregularly 

 spherical in form and are dis- 

 tinguished by conspicuous 

 granules within their proto- 

 plasm possessing a strong 

 alifinity for dahlia and other 

 basic aniline stains. They 

 include the plasma-cells of 

 Waldeyer and the jnast-cells 

 of Ehrlich. 



Pigment-Cells. — The 

 fixed cells sometimes contain 

 accumulations of dark parti- 

 cles within their cytoplasm, 

 the elements then appearing 

 as large, irregularly branched 

 pigment-cells; these are con- 

 spicuous in man within the choroid, the iris, and certain parts of the pia mater. 

 The nucleus usually remains uninvaded, and hence appears as a lighter area within 

 the dark brown, or almost black, cell-body. 



The Intercellular Constituents of the connective substances occur in three 

 forms, — fibrous tissue, ?-eticiilar tiss?ie, and elastic tissue. 



Fibrous tissue consists morphologically of varying bundles of silky fibrils of 



Connective- 

 tissue cell 

 (Fixed cell) 



Migratory 

 leucocytes 

 7--/^^ (Wandering 

 cells) 



[ ibrous 

 tissue 



Elastic 

 fibres 



Section of subcutaneous tissue, showing the usual constituents of areolar 



tissue. X 300. 



