COXXECTIVE TISSUES 



21 



8. Photomicrograph of small part of a 

 longitudinal section of a muscle of a rabbit, 

 showing part of the tendon, composed of con- 

 nective tissue fibres, with coarse muscle fibres 

 joining it obliquely at each side. X 100. 



the dorsal ligament of the neck (ligamentum nuchae) where greater 

 elasticity is required. The ligament is not so conspicuous in the 

 rabbit as in larger mammals, 

 where the yellow coloration 

 is very noticeable. Elastic 

 membranes composed chiefly 

 of yellow fibres with scattered 

 cells occur in the walls of 

 blood vessels and of dis- 

 tensible viscera. 



Since the fibres are non- 

 living and cells are few in 

 tendons, ligaments, and elastic 

 membranes, vessels also are 

 few in these situations. 



Fat or adipose tissue is a soft form of connective tissue in which 

 the cells predominate over the intercellular components and are 

 greatly enlarged by the inclusion of relatively enormous quantities 

 of fat in the form of globules. Each globule is enveloped by a thin 

 film of cytoplasm, which is slightly thickened at one side to 

 contain the flattened nucleus of the cell. Such tissue tends to 

 occur in certain definite situations, such as in association with the 

 blood-vessels, but also is found in locations where areolar connective 

 tissue might be expected to occur. Special fat masses, sometimes 

 distinguished by unusually dark coloration, occur at the side of the 

 neck and between the shoulder blades of the rabbit. In the foetus 

 (cf. Plate VI) these are represented by large masses of vascular 

 connective tissue. They correspond with the so-called storing or 

 hibernating glands of certain other mammals. 



Coloration or pigmentation of certain portions of the body, 

 especially of the skin and hairs and of the retina, the ciliary body, 

 and the iris of the eye, is due to the presence of pigment granules, 

 partly in special connective tissue cells, chromatophores, and partly 

 in epithelium. The absence of such granules in animals belonging 

 to species normally coloured constitutes albinism, a condition 

 indicated by the whiteness of the hair and by the pink colour of 

 the eyes, the latter being due to the circumstance that the blood- 

 vessels of the vascular tunic are not concealed by pigment. 



