A TYPICAL ORGANELLE — ROOTS 27 



Rouiller and Faure-Fremiet (1958) found that granules present in 

 the resting (shaftless) kinetosomes of the peritrich ciUate Ophryditim 

 disappear on development of the ciliary shaft. Larger structures 

 of a variety of shapes have been observed in the centres of basal 

 bodies; sometimes they are amorphous masses, and sometimes 

 fibres like those in Euplotes cilia (shown in PL IVb) that Roth 

 (1956) believes to be continuous with the central fibrils of the 

 shaft. A complex cartwheel structure of radiating fibres has been 

 found in Pseudotrichonympha and Trichonyinpha (see p. 55 and 

 PI. I) and also in Paramecium Gibbons (1960) and the trypanosome 

 Blastocrithidia (Vickerman, 1962). 



The peripheral fibrils, which appear as triplets of tubular 

 subfibrils in the basal body wall in the best resolved transverse 

 sections, can usually be traced through to the inner end of the 

 basal body. In some cases, e.g. rat tracheal cilia (Rhodin and 

 Dalhamn, 1956), the subfibrils become less regularly arranged 

 towards the inner end and some diverge and continue into the 

 cytoplasm as short rootlets. More frequently the fibrils continue 

 in their ordered arrangement to the inner end of the basal body, 

 where they terminate at more or less the same level. Lateral 

 inter-connexions between adjacent triplets may be quite distinct, 

 as in Pseudotrichonympha (Plate I), where the main connexions 

 are about 45 A thick, though it is uncertain whether they are 

 fibrils or longitudinal laminae. More usually there is a thick 

 annular zone of dense material in which the peripheral fibrils are 

 embedded to form the basal body cylinder; the use of improved 

 techniques may allow this zone to be further resolved in these 

 cases. 



Ciliary Roots 



Rootlet structures which make connexion with the basal 

 bodies, and run in the cell cytoplasm, form the most variable part 

 of the ciliary structure, but fall into three main categories. Firstly, 

 there are fine fibrils about 150 to 300 A in diameter with a tubular 

 appearance in transverse section, which are frequently aggregated 

 into bundles (see e.g. PL IVa, Va, Xlllb). These fibrils are 

 usually " connected " to some other structure in the cell, often the 

 basal bodies of other cilia or similar fibrils from other basal 

 bodies, but sometimes they appear to end blindly in the cytoplasm. 



