768 



YVETTE KUNZ 



Thus, it is concluded that the formazan deposits in the outer and inner 

 segments of ail three types of cônes represent LDH activity. The outer segments 

 of the rods, however, are devoid of this enzyme. The " nothing dehydrogenase " 

 observed in this région is probably alcohol dehydrogenase, an enzyme engaged in 

 the visual process. As previously mentioned, the inner segments of the rods cannot 

 be seen with certainty since pigment is accumulated in the région. 



L I G H T 



Fie. 12. 



Outer segments of rods (adult, light adapted eye of Lebistes) Kryostat sections, subjected to 



variations in the staining method. 

 Incubation mixture as for fîg. 4. 

 Incubation mixture as for fîg. 4. 

 acétone treatment prior to incubation. 

 3 M urea added to incubation mixture, 

 lactate omitted from incubation mixture, 

 incubation at 4° C (instead of 37° C). 



(3-Diphosphopyridine nucleotide omitted from incubation mixture. 

 Phenazine methosulphate omitted from incubation mixture. 

 Polyvinylpyrrolidone added to incubation mixture. 



blue granules, 

 light pink stain. 

 strong pink stain. 



Inspection with oil immersion of sections treated with the inhibitor, revealed 

 the very same picture as given above for total LDH activity, with the only différence 

 that the staining of inner and outer segments of cônes is less intense (fig. 11). 



Developing eye : 



Only results of the light adapted eye are reported. Lebistes is viviparous; the 

 embryonic period lasts 30 days at 22°C. The différent embryonic stages have been 

 described previously (Kunz, 1963, 1964, 1971). 



Normal = 



Normal = 



Acétone = 



Urea = 



No lactate = 

 4°C 



No DPN = 



No PMS = 



PVP - 



= 



H - 



