THE MORPHOLOGICAL APPROACH 71 



cultures of carcinoma and sarcoma and later in spleen, especially in response 

 to such foreign bodies as lycopodium spores and cotton fibers (Lambert, 

 1912). Giant cells may form with the stimulus of tubercle bacilli (Timofe- 

 jewsky and Benewolensjkaja, 1925), as the result of X-ray (Puck and Marcus, 

 1956; Pomerat et al., 1957). Abnormal mitosis is produced by sublethal 

 amounts of mustard gas (Fell and Alsopp, 1948). The basic reason for this 

 imbalance between nuclear and cytoplasmic division is not known. Giant 

 cells may arise either by a merging of cells or by failure of cytoplasmic 

 division. 



F. Amino Acid Deficiencies 



Demonstration of the amino acid requirement of cells (Kieler, 1953, 1954; 

 Eagle, 1955), and that there are certain vitamin requirements (Eagle, 1955a), 

 has been accompanied by the suggestion that the different amino acid de- 

 ficiencies produce morphologically different cellular lesions. In such examples 

 as arginine deficiency, cell degeneration was so pronounced that only sudano- 

 philic vacuoles and nuclei remained (Kieler, 1953). However, high resolution 

 phase microscopic studies have not been reported. 



G. Cytoplasmic and Nuclear "Degenerative" Changes 



In an excellent and somewhat neglected study of the changes which occur 

 when tissue cultured cells are not refed, Horning and Richardson (1929) 

 followed their morphology, both in the living state, with Janus green and 

 neutral red dye, and in the fixed state, after osmic acid vapor fixation and 

 staining. Chick embryo heart cells, kept for 50 hours and more in unchanged 

 media, became elongated and developed needle-like processes which often 

 had swollen tips. Pieces of these extrusions broke off. There was extensive 

 pseudopodial activity, with bizarre branching and sporadic division of 

 nucleoli. By the third to fourth day, masses of lipoid had accumulated, the 

 cell contour had changed, but "it is interesting to observe that up to this 

 advanced stage of cellular degeneration that occurs after 7-8 days in vitro, 

 the nucleus remains relatively unaltered. The nuclear membrane is intact 

 until the cytoplasm has lost all of its distinguishing features." Chromato- 

 lysis took place at 7-9 days, but the nucleolus persisted. In the final stages 

 of cytolysis, mitochondria and neutral red granules still persisted. The 

 degenerative changes in undifferentiated cells were essentially similar but 

 differed somewhat in sequence. In a cytochemical study of pycnotic nuclear 

 degeneration, Leuchtenberger (1950) followed the changes with a photo- 

 metric Feulgen method for DNA. She found that the nuclei of sarcoma 180 

 and liver cells, when killed and transferred subcutaneously, progressively 

 shrank, the chromatin became homogenous, and the nucleoli disappeared. 

 The protein was initially reduced to one-half; later, there was a loss of DNA. 



