846 C. M. .IA('KSON 



Diirhip; inanition, the pars intcn-jnedia presents a varied struc- 

 ture, but on lli(^ whole the changes are usually not very marked. 

 These changes are somewhat similar in the young rats held at 

 maintenance, and in the older rats subjected to acute and chronic 

 inanition. 



The cytoplasm during inanition as a rule does not appear less 

 abundant than in the normal animal, except in certain atrophic 

 areas of variable size and number. Here the cytoplasm may be 

 scanty, and the nuclei closely packed. In structure, however, 

 the cytoplasm usually appears altered, more rarefied and sparsely 

 granular in appearance. Sometimes it assmiies a markedly 

 reticular or vacuolated appearance, but this is not constant. 

 Around pycnotic nuclei, the cytoplasm usually assumes a more 

 dense and homogeneous appearance, and stains more deeply 

 basophilic. 



The nuclei of the pars intermedia cells during inanition, ac- 

 cording to the measurements above given (table 4) show a slight 

 decrease in size, though frequently wdth but little evident change 

 in structure. There is usually a definite tendency to hyper- 

 chromatism, however, less marked in some cases but distinct in 

 others (especially when the inanition is extreme). In some cases, 

 especially in the atrophic areas above referred to, the nuclei 

 present variable degrees of pj'cnosis. Karyorrhexis and karyoly- 

 sis are rare. 



In this connection may be mentioned the 'colloid.' The col- 

 loid-like masses in the pars nervosa have already been con- 

 sidered. In the rat, colloid does not occur in the pars inter- 

 media, but is usually found in the lumen of the hypophyseal 

 cavity, at and after the age of three w^eeks. The amount is 

 small, though somewhat variable. It presents marginal vacuoles 

 resembling those in the colloid of the thyroid follicles. Traut- 

 mann ('09) mentions vacuoles in the colloid of the hypophysis 

 of domestic animals, but considers them artefacts. If these 

 vacuoles are interpreted as secretion phenomena, it is of interest 

 to note that in the rat they appear more typically and fre- 

 quently on the surface toward the pars intermedia, more rarely 

 on the surface next to the pars anterior. No constant changes 



