MORRIS POLLARD 
1007 
Table II. — Lesions observed in Female Germfree Mouse 
Strains 
CFW 
C3H 
Balb/c 
Swiss- Webster 
Number examined 
32 
55 
19 
39 
Lymphatic leukemia 
1 (4)* 
1 (3) 
Breast carcinoma 
2 (X, 23) 
5 (4, 10, 10, 
1 (13) 
4 (5, 5, 11, 
16, 17) 
11) 
Fibrosarcoma 
2 (7, 18) 
1 (5) 
Lymphosarcoma 
1 (18) 
1 (6) 
Osteosarcoma 
Fibroma 
1 (9) 
Amyloidosis 
1 (23) 
Negative 
24** 
50 (6) 
18 (14) 
32 (10) 
* Number of mice with lesions (age in months) . 
** Negative: 17 females (11, 11, 11, 11, 11, 12, 12, 12, 13, 
14, 14, 18, 18, 25, 25, 25, 26); 
7 males (12, 12, 13, 13, 14. 14, 23). 
X — not recorded. 
spontaneously and in significant numbers. In 
the course of ten years, only 2 mice, from 
among the remaining strains, have (Jeveloped 
lymphatic leukemia spontaneously (Table II) ; 
but leukemia can be induced in all strains by ad- 
ministrations of whole-body x-irradiation.^i 
Germfree and conventional AKR mice manifest 
the same incidence (over 95%) and type of dis- 
ease, at average age of 8 months; and all of 
them die within 7 days after onset of symptoms. 
Occasionally, younger germfree AKR mice have 
developed spontaneously what appears to be a 
"wasting" syndrome which has been inter- 
preted possibly as an early manifestation of 
leukemia.22 They appear kyphotic and rough 
and are disinclined to move. In such mice, the 
thymus glands are involuted; but the spleens 
and lymph nodes are swollen with cords of plas- 
ma-type cells. They usually manifest perianal 
dermatitis and diarrhea, and they usually die 
within 7 days after onset of symptoms. This 
"wasting" syndrome has not been observed in 
conventional AKR mice nor in germfree mice of 
other strains. 
Spontaneous breast carcinomas have been ob- 
served in four strains of germfree mice (Table 
II), and "B"-type virus particles (as well as 
"C"-type particles) have been noted in the tu- 
mors of three strains by electron micro- 
scopy.-''-'* In spite of this obvious virus 
contamination, the incidence of spontaneous 
breast carcinomas among them has been rela- 
tively low. This may be related to standards of 
husbandry. The data recorded in Table II fails 
to set an accurate incidence level of breast tu- 
mors because candidate mice had been with- 
drawn continuously from the breeding colonies 
for other studies, which were often terminated 
before the mice had reached 6 months of age. It 
is significant to note here, and as recorded 
earlier,23.24 that germfree mice do carry "B"- 
type virus particles. A confirmatory report on 
germfree Balb/c mice indicates that their tu- 
mors are similar to those observed in conven- 
tional mice.2^ 
A mouse strain (designated "Haas") with 
congenitally-transmitted lymphocytic choriom- 
eningitis virus has now been propagated in 
germfree status through 22 generations." All 
of them have shown a life-long viremia (10^ 
LD.-,n/ml blood). They remain disease-free until 
age 5 months, and then small microscopic accu- 
mulations of lymphoid cells appear in the 
visceral organs, which expand with age. The 
swollen lymph nodes and spleens contain large 
germinal zones and masses of lymphoid cells, 
many of them plasma cells. The serum globulin 
levels become elevated ; and degenerative lesions 
appear in the glomeruli.-'' The glomerular vessels 
become occluded by accumulations of fibrinoid 
material ;2'^ and eventually the glomeruli be- 
come hyalinized, sclerosed and obliterated. 
Glomerulonephritis is a classical lesion in this 
mouse strain. Arteritis has been described in 
them.28 The Haas mice usually show clinical 
evidence of disease at 9 months, and they die 
about 12 months of age. Their visceral organs 
are distorted and infiltrated extensively with 
lymphoid cells which are assembled to form 
plasmacytomas and reticulum cell sarcomas. 
Immunoproliferative lesions develop also in 
conventional Haas strain mice, but their lesions 
are not so precisely defined because of compli- 
cating bacterial infections. The passage of LCM 
virus in Haas strain mice via transovarial 
and/or transplacental routes is now being 
determined. 2^ 
Genetic Diseases 
Two strains of germfree mice (NZB and 
SJL/J) have manifested the same disease syn- 
dromes as the conventional stock from which 
they had been derived.^^'^^ While leukemia-re- 
lated "C"-type virus particles have been ob- 
served in them, their etiological relationships to 
