80 ELECTRON-MICROSCOPIC STRUCTURE OF PROTOZOA 



In Hartmannella (Pappas, 1959) these are in intimate contact with 

 mitochondria, an association often observed in metazoan cells. 

 Although many light microscopists have been unable to identify 

 Golgi elements in Amoeba, small piles of thin flat membranous 

 sacs with adjoining micro vesicles have been seen in A. proteus and 

 most of the other amebae studied. By morphological criteria these 

 clearly are classifiable as Golgi bodies. 



Other particulates seen in electron micrographs but of unknown 

 significance include very dense granules, 30 to 50 m/x in diameter, 

 liberally distributed through cytoplasm and nucleus, occurring 

 even within mitochondria, and sometimes concentrated on surface 

 or vacuolar membranes. 



An interesting recent observation by Roth and Daniels (1961) 

 concerns infective organisms occurring in the cytoplasm of 

 Amoeba proteus. In electron micrographs these were visible as 

 single or multiple rod-shaped or spiral structures resembling 

 bacteria, enclosed in vesicles. With phase contrast microscopy, 

 the authors observed rupture of the ameba cell and its enclosed 

 vesicles and the release of motile organisms into the surrounding 

 fluid. Attempts to eliminate the infection by starvation, penicillin 

 treatment and irradiation were unsuccessful. As the authors point 

 out, these inclusions may be significant in view of the common 

 use of Amoeba for studies of DNA and RNA synthesis. Evidence 

 of cytoplasmic activity has been brought forward by workers 

 who have suggested as one possibility the presence of symbiotic 

 organisms. 



Cytoplasmic structures of the parasitic amebae do not differ 

 conspicuously from those of the free-living forms. However, in 

 Entamoeba invadens, Deutsch and Zaman (1959) found no structures 

 identifiable as mitochondria, and Osada (1959) reported the 

 absence of mitochondria from E. histolytica. The same is true of 

 some other parasitic protozoa, in which, presumably, energy 

 release by electron transfer to oxygen does not occur. 



Precystic individuals of species of Entamoeba typically produce 

 crystalloid inclusions called chromatoid bodies, recognized by 

 their strong refringence in life and by their pronounced basophilia. 

 They gradually disappear in the cyst. According to Barker and 

 Deutsch (1958) and Deutsch and Zaman (1959), precursors of the 

 chromatoid bodies in feeding stages of E. invadens appear as small 



