24 PRACTICAL HISTOLOGY. 



EXAMINATION (L). Observe the sheath of the tendon, composed of connective-tissue 

 fibres disposed circularly. It sends processes into the substance of the tendon, subdividing it 

 into polygonal areas. These areas are made up of the cut ends of the longitudinally disposed 

 fibres which constitute the tendon. Each area has scattered in it a number of small specks 

 deeply stained by the logwood, united by fine lines. These are the spaces the inter-fascicular 

 lymph-canals between the bundles of fibres, and in each space a corpuscle may be detected 

 (PI. IV., Fig. 6). 



(H). The great mass of the tendon is but slightly stained, but notice the sections of the 

 corpuscles, which are deeply tinted. The corpuscles give off processes which may be traced 

 a certain distance between the fibre-bundles. Amongst the cut ends of the fibres may be 

 seen small, light, refractive points ; these are the ends of elastic fibres few in number 

 which exist in tendon (PI. IV., Fig. 7). 



The branched interfascicular spaces in the transverse section are best seen in a transverse 

 section of a dried tendon examined in water. The spaces appear branched and black and 

 larger than natural, from the shrinking of the bundles of fibres bounding them. They are 

 black because they contain air. The addition of glycerine renders all the parts too trans- 

 parent, hence such a preparation is not permanent. 



Sometimes the logwood stains the section of an almost uniform dark violet tint, and it 

 becomes impossible to distinguish the corpuscles from the rest of the section. Under 

 these circumstances, irrigate the over-stained section with a five per cent, dilution of glacial 

 acetic acid, examining the section all the time with a low power. The colouring matter will 

 be dissolved out of the fibres and remain in the corpuscles, and if the acid is thoroughly 

 washed out of the preparation, this may be mounted in Farrant's solution and preserved. It is 

 well to place such a section for a few minutes in a five per cent, solution of bicarbonate of 

 soda to remove all the acid. This process of overstaining a section with either logwood or 

 carmine, and getting rid of the excess by means of acetic acid, is frequently of value. 



LONGITUDINAL SECTION. 



(2) Place a section on a slide and stain it with logwood, as directed for a transverse sec- 

 tion. 



EXAMINATION (H). Observe the fibres arranged longitudinally, many of them slightly 

 wavy, their outlines indistinct and always unbranched. Between the fibres, which are but 

 slightly stained or not at all, rows of elongated fusiform corpuscles deeply stained are 

 observed. Study these corpuscles. They are nucleated and the nucleus is surrounded by a 

 granular mass of protoplasm which forms part of the body of the corpuscle. They are fixed 

 connective-tissue corpuscles or ' tendon cells,' and are most numerous in young tendons 

 (PI. IV., Fig. 5). 



(3) Tease out with needles a small piece of a section treated as (2). The fibres and cor- 

 puscles are easily isolated. Notice the nucleated granular corpuscles in many cases adhering 

 to and partly encircling a fibre. These corpuscles when seen on edge are fusiform, but when 

 detached and seen on the flat they are more or less flattened, with their edges sometimes turned 

 in. These cells partly surround and form an imperfect sheath for the fibres. 



Ranvier has shown that the relations of the cells to the fibres of a tendon can be more 

 successfully made out in the fine tendons found in the tail of a young rat or mouse. 



