W. p. MCNULTY 
831 
Figure 1. — Mite infection in a male rhesus monkey. 
Sections of mites may be seen in a dilated bronchus, 
showing muscular hypertrophy and adjacent chronic 
inflammation and pigment deposition. H & E, 31x. 
muscle is hypertrophic, and in the peribronchial 
connective tissue and adjoining alveoli are dense 
accumulations of lymphocytes, histiocytes, and 
eosinophils. Pigment of at least two kinds is 
present, one of v^hich we believe is a hemoglobin- 
derived fecal discharge from the mites, the 
other fragments of chitin (Fig. 1). 
Of great interest are associated changes in 
pulmonary arteries, which also seem to be of 
two kinds. Those arteries immediately adjacent 
to mite lesions are markedly irregular; the 
intima is erratically thickened and the elastic 
fibers in the media are fragmented and dis- 
torted (Fig. 2). These changes seem to be 
caused directly by the mites, and Woodard - has 
described mites apparently lodged in or migrat- 
ing through pulmonary arterial walls. 
In severely affected animals all pulmonary 
arteries are tortuous and heavy-walled with 
thickened intima. This is true for vessels at a 
distance from the parasites (Figs. 3, 4) ; even 
the main pulmonary artery may be involved 
(Fig. 5). By gross inspection we have recog- 
nized right ventricular hypertrophy in only one 
case, and we have just begun to collect ratios 
of the weights of the right and left ventricular 
walls. 
We suspect that pulmonary hypertension is 
present and suggest this may be a useful model 
Figure 2. — Large branch of pulmonary artery in male 
rhesus monkey infected with mites. The vessel is 
tortuous and thickened ; the elastic lamellae are frag- 
mented. Acid orcein Verhoeff, 60x. 
for exploration. The animals appear clinically 
unaffected except for a cough, but the severity 
of infection may be estimated in life by radio- 
graphs of the chest. To date no physiologic 
measurements have been made of pulmonary 
vascular and ventilatory function. 
Pulmonary emphysema 
Emphysema may be systematically studied 
and classified as to anatomical type only by 
Figure 3. — Cut surface of fixed lung, male rhesus mon- 
key infected with mites. Thickened pulmonary 
arteries are prominent. 
