2 L. F. Belanger, T. Semba, S. Tolnai, D. H. Copp, L. Krook, C. Gries 



Jaffe (1933), Kind (1951) and Lipp (1954, 1956), with the light microscope and more 

 recently by Baud (1962) with the electron microscope. 



RuTiSHAusER and Majno (1951) made the interesting observation that during its 

 hypertrophic or oncotic phase, the osteocyte produced alkaline phosphatase. The sub- 

 sequent death of the osteocyte, leaving empty lacunae which oftentimes fill with 

 calcium salt (Sherman and Selakovitch, 1957; Sissons, 1964) has been related by 

 DuFOUR (1952) and by Urist et al. (1963) to osteoporosis and other rarefying 

 diseases of the skeleton. Empty lacunae have also been recognized as a conspicuous 

 feature of old age (Frost, 1960; Sissons, 1964). 



Recently, Lipp (1959) has detected the presence of aminopeptidase in some of the 

 osteocytes. On the other hand, Belanger and Migicovsky (1963 a) have shown that 

 these cells contained an enzyme capable of digesting gelatin. Furthermore, Belanger 

 et al. (1963 b) have been able to associate the same areas with toluidine blue meta- 

 chromasia and also with organic matrix and salt depletion as revealed by alpharadio- 

 graphy (Belanger and Belanger, 1959) and X ray microradiography (Belanger 



Fig 



ed by 



-diaphysis of an 2 days-old chick embryo. The cell is apparently closely 

 idoplasmic reticulum, ribosomes and mitochondria are prominent features 

 of the cytoplasma 



et al., 1963 a). To designate specifically this intimate form of resorption related to 

 osteocytic activity, the abused term osteolysis has been proposed (Belanger et al., 

 1963 b; Belanger, in press). 



