18 



W. A. DE VOOGD VAN UER StRAATEN 



From these important observations Gaillard draws a number of direct and 

 indirect conclusions: 1. First of all that for the expression of the complete effect of 

 PTE on the explants the unhampered production of certain proteins is necessary. 

 2. Moreover that the action of PTE is more closely associated with the production of 

 m-RNA than with the Puromycin sensitive synthetic activities at the ribosomal level. 



In cuhivated radius rudiments 

 PTE induces 7 phenomena 



Actinomycir 

 interferes wi 

 developmem 

 set of pheno 



1 D 



1th the 

 : of the 

 mena 



Bone: 



1. Loss of osteoblasts 



2. Bone resorption 



3. Increase of osteoclasts 



Cartilage: 



4. Loss of hypertrophic cells 



5. Conic transformation of epiphyses 



6. Loss of azurophylia 



Conn, tissue: 



7. Proliferation of connective tissue 

 inside the shaft 



Puromycin does interfere 

 .with the development of 

 the phenomena 1 ±4 



: Puromycin does not 

 ; interfere with the 

 —development of the 

 : phenomena 5 + 7, 

 : especially not with 

 ■ phenomenon 7 



Fig. 4. The 7 morphological ch.inges, characteristic for the action of PTE on cultivated mouse radius rudiments 

 according to Gaillard and the antagonistic effect of Actinomycin D and Puromycin 



At this point I would like to bring again to your attention the idea that PTE could 

 act by inducing quantitative changes in the NAD and/or NADP biosynthetic appa- 

 ratus. 3. The observation that the hormone-induced proliferation of connective 

 tissue is, so to say, "Puromycin resistant" brings Gaillard to a most interesting 

 consideration. This finding seems to suggest that different receptors might exist for 

 the biosynthetic mechanism of cell reproduction and for the production of specific 

 secretions of a proteinaceous character. And although in this special case the postu- 

 lated receptors have to be localized in different types of cells, the question rises 

 whether we have to generalize and to postulate two different systems in each indi- 

 vidual cell. Perhaps we find a morphological substrate of this concept in the well 

 known dichotomy in free and membrane attached ribosomes. 



In the light of Gaillard's observations Rasmussen's (1964) idea that Actino- 

 mycin D interferes with the PTE stimulated differentiation of osteoclasts, thus inter- 

 fering with osteoclastic bone resorption, seems to be oversimplified. In fact the lesson 

 to be drawn from Gaillard's experiments is, that the hormone effect is polymorphic 

 and that it does not fit into a concept dealing primarily or even exclusively with 

 osteoclastic function. 



Although not directly connected with this subject I would like to make a final 

 digression. In thinking about protein synthesis and the production of proteins for 

 specified different purposes outside the cell, we are confronted with a serious lack of 

 knowledge concerning the mechanism of extrusion. It is certainly dubious whether 



