T H E BIOLOGY OF T E R A T O M A S
25
XIII. Experimental Induction of Teratomas
A. In Fowl
Spontaneous testicular teratomas are very rare in birds, but they have
been induced by the injection of zinc and copper salts by many investigators. The results of investigations on the zinc induced testicular teratomas in fowl has been summarized by Bresler (1964).
Guthrie (1964) summarized the results of investigations into the
mechanisms involved in experimentally induced testicular teratomas in
fowl and added eight cases of his own. Nearly all investigators found
that they could be induced during the early spring months when spermatogonia are actively dividing. Bagg (1936) induced teratomas in
seasons other than spring by using gonadotropic hormones in addition
to zinc salts.
B. In Adult Mammals
Bresler (1959, 1964) has succeeded in inducing testicular teratomas in
mice by injecting an emulsion of CuS0 4 and testosterone propionate
into the testes of adult white mice. He found that the hormone was
necessary. He injected 5% ZnCl 2 into rat testes and obtained three
testicular teratomas. ZnCl 2 kills much of the testis, and Bresler suggested that this would increase the level of gonadotropic hormones, again
resulting in tumor formation. Bresler concluded that testicular teratomas
originate from "pathological cleavage of spermatogonia and formation
of three germ layers . . . and a trophoblast." He also obtained one teratoma in a graft of a newborn testis into the spleen of a castrated adult,
and suggested that increased levels of gonadotropic hormones were
responsible for the development of the tumor.
We prepared an emulsion of CuS0 4 like Bresler's and injected it into
both testes of 63 strain 129 mice. This emulsion contains Formalin and
is toxic. Only 17 of our mice survived. They were injected with testosterone propionate according to the schedule described by Bresler. Histological examination revealed that there was damage to all testes, but
no teratomas were observed. The primordial germ cells of fetal strain
129 mice are very susceptible to teratocarcinogenesis (see below), but
the spermatogonia of adults are apparently more resistant than those
treated by Bresler. It would be interesting to repeat Bresler's experiments using other inbred strains of mice. The author thinks the most
significant conclusion from Bresler's work is that the adult spermatogonia
are susceptible to teratocarcinogenesis.
25
XIII. Experimental Induction of Teratomas
A. In Fowl
Spontaneous testicular teratomas are very rare in birds, but they have
been induced by the injection of zinc and copper salts by many investigators. The results of investigations on the zinc induced testicular teratomas in fowl has been summarized by Bresler (1964).
Guthrie (1964) summarized the results of investigations into the
mechanisms involved in experimentally induced testicular teratomas in
fowl and added eight cases of his own. Nearly all investigators found
that they could be induced during the early spring months when spermatogonia are actively dividing. Bagg (1936) induced teratomas in
seasons other than spring by using gonadotropic hormones in addition
to zinc salts.
B. In Adult Mammals
Bresler (1959, 1964) has succeeded in inducing testicular teratomas in
mice by injecting an emulsion of CuS0 4 and testosterone propionate
into the testes of adult white mice. He found that the hormone was
necessary. He injected 5% ZnCl 2 into rat testes and obtained three
testicular teratomas. ZnCl 2 kills much of the testis, and Bresler suggested that this would increase the level of gonadotropic hormones, again
resulting in tumor formation. Bresler concluded that testicular teratomas
originate from "pathological cleavage of spermatogonia and formation
of three germ layers . . . and a trophoblast." He also obtained one teratoma in a graft of a newborn testis into the spleen of a castrated adult,
and suggested that increased levels of gonadotropic hormones were
responsible for the development of the tumor.
We prepared an emulsion of CuS0 4 like Bresler's and injected it into
both testes of 63 strain 129 mice. This emulsion contains Formalin and
is toxic. Only 17 of our mice survived. They were injected with testosterone propionate according to the schedule described by Bresler. Histological examination revealed that there was damage to all testes, but
no teratomas were observed. The primordial germ cells of fetal strain
129 mice are very susceptible to teratocarcinogenesis (see below), but
the spermatogonia of adults are apparently more resistant than those
treated by Bresler. It would be interesting to repeat Bresler's experiments using other inbred strains of mice. The author thinks the most
significant conclusion from Bresler's work is that the adult spermatogonia
are susceptible to teratocarcinogenesis.