142 



A. HOLMBERG 



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Fig. 3. Golgi apparatus from an animal fixed 15 minutes after injection of 10 mg Diamox per kg body weight. Several Golgi 

 units (arrows) with numerous small vesicles. Magnification 50 000. 



brane outside the cell surface membrane, is also 

 a characteristic of the epithelium of the proximal 

 convoluted tubule of the kidney (12, 15). Comparing 

 these epithelia from a functional point of view one 

 finds that they are similar to a certain extent. 



The mode of action of Diamox has not yet been 

 fully elucidated, but it is reasonable to assume that 

 its inhibition of carbonic anhydrase will interfere 

 with the formation of aqueous humour. Tonographic 

 studies (3) have also shown that the inflow of aqueous 

 humour into the eye is inhibited with about 60 "„. 



Are the changes seen in the ciliary epithelium in 

 fact due to the effect of Diamox and are these 

 changes responsible for the inhibition of the secre- 

 tion? After nephrectomy the diuretic effect of 

 Diamox is absent. The use of a control substance 

 (Diazil), which is physically and chemically similar to 

 Diamox but is lacking any effect on the intraocular 

 tension, other secondary effects can be excluded. 

 Therefore it seems highly problable that the changes 

 seen actually are due to the inhibitory effect of 

 Diamox on the secretion. 



As far as 1 know, no functional changes in the 

 Golgi apparatus have been observed earlier by means 

 of electron microscopy. It is beyond all doubt that 

 there is a marked alteration in the Golgi apparatus 



of the ciliary epithelium concerning both the amount 

 of vesicles and the arrangement of the membranes. 

 The interpretation of these changes is somewhat 

 difficult at this stage of the investigation, but they 

 may indicate that the Golgi apparatus really takes 

 part in the secretion according to the hypothesis 

 presented in light microscopic investigations. 



The fact that in the earlier stages of Diamox 

 inhibition a high amount of small vesicles accumu- 

 lates in the cytoplasm of the cells can be explained 

 by a sudden blockage of the outflow of aqueous 

 humor from the cell surface to the posterior cham- 

 ber and its accumulation in vesicles. From these 

 arguments it follows that the changes in the cyto- 

 plasm seen after Diamox injection may be secondary 

 to the inhibition of the secretion. 



References 



1. Barany, E., Acta Phys. Scaiul. 13, 55 (1947). 



2. — ibicL 13, 81 (1947). 



3. Becker, B., Amer. J. Ophlh. 11, 599 (1955). 



4. Davson et al., J. Physiol. 108, 203 (1949). 



5. Duke-Elder, S. and Davson, H., B. J. Opiuh. 33, 452 



(1949). 



6. Friedenwald, J., Arch, of Ophth. 210, 761 (1938). 



7. — B. J. Ophlh. 28, 503 (1944). 



