290 INANITION AND MALNUTRITION 



involution, and presents 5 stages: (1) Moderate fibrous proliferation, especially 

 interlobular; blood vessels strongly congested; differentiation of darker cortex 

 and lighter medulla not well marked; cells show mitoses; Hassall's corpuscles 

 polymorphic, but not abnormal. (2) The congestion and cellular hyperplasia 

 become decreased; interlobular connective tissue increased; lobular reticulum 

 more apparent, with sclerosis extending from vessels and septa; distinction 

 between cortex and medulla has disappeared; the various cell types tend to 

 homogeneity; lymphocytes, macrophages and eosinophile myelocytes become 

 rare; Hassall's corpuscles numerous and polymorphic. (3) The thymic lobules 

 become fragmented by sclerotic bands, proceeding especially from the 

 perivascular connective tissue; sometimes the normal lobular topography 

 appears inverted, the cortical zone through rarefaction and sclerosis becoming 

 clearer than the medulla; lymphocytes with opaque nuclei predominate; a 

 thin zone of mononuclears appears around the Hassall's corpuscles, which are 

 still numerous, but sometimes cystic. (4) The thymus is now largely 

 fibrous, with small, irregular lobules; homogeneity of cell types still 

 more evident; cell activity restricted to a small zone around Hassall's 

 corpuscles, which are chiefly cystic and sometimes united into irregular masses. 

 (5) Thymus now presents a fibrous (collaginous) mass, poor in cells, with a few 

 cell islands as remnants of the thymic lobules ; in the thickened reticulum appear a 

 few pycnotic lymphocytes; usually no traces of the Hassall's corpuscles remain. 



Tixier and Feldzer hold that the thymic sclerosis is comparable to that 

 occurring during inanition in other (especially the lymphoid) organs. 



The effects of inanition upon the thymus in atrophic infants are reviewed by 

 Lesage ('n) and Monckeberg ('12), who considered the thymic involution as an 

 effect, rather than a cause. Schridde ('13, '21), however, contends that the 

 atrophy of the thymus is a real factor in infantile malnutrition, or a cir cuius 

 vitiosus, inanition causing a sclerous atrophy of the thymus, which in turn 

 intensifies the malnutrition. Schridde also described an increasing amount 

 of fatty granules in the reticulum cells of the cortex; and a disappearance of 

 the lymphocytes and eosinophile leukocytes during the progressive sclerosis. 

 Plasma cells rarely occur (contrary to some authors). 



Cremieu ('12) claimed that the involution of the thymus by inanition, 

 X-rays, etc., is fundamentally similar to the normal age involution. "II ne 

 s'agit que dedeux modalites differents d'un processus uniforme: l'envahissement 

 conjunctif. D'un cote, le tissu conjonctif reste sec; de l'autre, il se charge de 

 vesicules adipeuses." 



Matti ('13) gave an extensive review of the work on thymic involution in 

 man and animals. 



Hornowski ('13) found the weight of the thymus usually varying directly 

 with the general nutritive condition in the newborn. Lesage and Cleret ('14) 

 emphasized sclerosis during athrepsia as the characteristic change, occur- 

 ring to a variable degree in all organs, especially in the thymus. 



Mattei ('14) gave a careful description of the changes in the atrophic thymus 

 of athreptic infants, his findings being in general agreement with those of Lucien 

 and Feldzer. He concluded that "Le tissu propre de l'organe presente 



