YELLOW FIBROUS TISSUE. 



273 



Fig. 173. 



Fig. 174. 



cells, receives increasing support from recent investigations. These 

 are peculiarly fusiform or stellate, sharply -pointed cells, producing 

 long fibres or reticulations by their coalescence. The nuclei some- 

 times remain in the elongated or fibriform cells, and thus the latter 

 have been termed nucleus fibres. (Gerber.) In other cases all traces 

 of the nuclei disappear, and perfectly homogeneous fibres or net- 

 works are produced. These may remain fine through life as at 

 first, or become coarse by increase in thickness. When once per- 

 fectly developed, the fibres^undergo very little change ; though so 

 long as the nuclei or other indications of the original cells still 

 appear, a certain amount of metamorphosis and repair may take 

 place (p. 269). 



It is the development of the nuclear fibres almost alone that has 

 been accurately examined ; and Kolliker has demonstrated that they 

 are formed from fusiform cells, 



T^otf to BOS f an i n h i n length, 

 which first appear in the foetus of 

 from two to three months (Fig. 

 173), the fibres of the white fibrous 

 tissue being already well formed. 

 In the foetus, at birth, the cells 

 have so elongated, and coalesced 

 into a network, that they can no 

 longer be isolated as before. 



What is asserted of the nuclear 

 fibres also holds good of the larger 

 elastic fibres ; for there is reason 

 to believe that all these have at 

 one time been nuclear fibres. In 

 fact, there is not a single true elas- 

 tic fibre in the new-born child; 

 since even those of the ligament- 

 um nuchaB, &c., when largest, are 

 not more than T ^o^ to T^W of 

 an inch in diameter (Fig. 174), and 

 from these, doubtless, the coarse 

 fibres are subsequently developed. 

 In some places, even in the adult, 

 the original condition of a system 



Of Canals (tubular Cells) is Still tO born infant. Magnified 350 diam'rs. (Kolliker.) 

 18 



\ 



\ 



\ 



Fig. 173. Formative cells of the elastic fibres 

 from the tendo-Achillis. a. Of a four months' 

 embryo. 6. From a seven months' foetns ; a few 

 cells free, with one and two processes, others 

 united by twos and threes. (Mag'd 350 diams.) 



Fig. 174. Stellate formative cells of the nu- 

 clear fibres out of the tendo-Achillis of a new- 



