24
LEROY C. STEVENS
Marin-Padilla and Benirschke (1963) associated treatment by thalidomide with the development of a germinal tumor (choriocarcinoma) in an
armadillo. The tumor formed many structures which were identical to
the early stages of an armadillo embryo. The embryoid bodies were
located in blood vessels and in early growths of metastatic nodules,
especially in the lungs.
Teratomatous embryoid bodies of the mouse were first observed in a
retroperitoneal metastatic growth of testicular origin (Stevens, 1959).
The primary germ layers were inverted as is typical for the mouse,
and they were composed of an outer layer of cells resembling endoderm
and an inner layer resembling ectoderm. When some sublines of transplantable teratomas are grafted into the peritoneal cavity, thousands of
free-floating embryoid bodies similar to mouse embryos 5 and 6 days of
age are contained in the peritoneal fluid (Fig. 4).
Pierce et al. (1960) found that the embryoid bodies of the mouse
originated by sloughing of partially necrotic areas of solid intraperitoneal
growths into the ascitic fluid. There, granules developed into typical
embryoid cysts composed of elements of the three germ layers. Stevens
(1960) observed that embryoid bodies can also arise by division of
pre-existing free-floating embryoid bodies.
Pierce and Verney (1961) observed that new embryoid bodies developed from a transplanted testicular teratoma of the mouse in vitro. They
probably originated as small aggregates of embryonal carcinoma lying
superficially in a necrotic portion of an expiant that was overlaid by a
layer of visceral yolk sac. The aggregates grew and became detached
from the main growth.
Pierce and Verney (1961) observed the development of cystic embryoid
bodies from expiants of teratocarcinoma that were maintained for as
long as 5 months as organ cultures. The microscopic structure of the
tumors developed subcutaneously from expiants of embryoid bodies
in vitro for 6 months was compared to that of a series of control tumors
developed subcutaneously from embryoid bodies that had never been
in vitro. The control tumors consisted predominantly of brain tissue,
whereas the dominant tissue in the experimental tumors was striated
muscle. Almost all of these tumor strains lost their muscle-producing
ability after two or three passages subcutaneously in mice. Long after
tissue cultures had lost the pattern of the original explanted embryoid
bodies, new embryoid bodies were observed to develop in them.
It has already been mentioned that the embryoid bodies of the mouse
not only resemble normal early mouse embryos, but have similar embryonic potency. When grafted subcutaneously (Pierce and Dixon,
1959a) or into the anterior chamber of the eye (Stevens, 1960), they
develop into teratomas composed of many types of tissues.
LEROY C. STEVENS
Marin-Padilla and Benirschke (1963) associated treatment by thalidomide with the development of a germinal tumor (choriocarcinoma) in an
armadillo. The tumor formed many structures which were identical to
the early stages of an armadillo embryo. The embryoid bodies were
located in blood vessels and in early growths of metastatic nodules,
especially in the lungs.
Teratomatous embryoid bodies of the mouse were first observed in a
retroperitoneal metastatic growth of testicular origin (Stevens, 1959).
The primary germ layers were inverted as is typical for the mouse,
and they were composed of an outer layer of cells resembling endoderm
and an inner layer resembling ectoderm. When some sublines of transplantable teratomas are grafted into the peritoneal cavity, thousands of
free-floating embryoid bodies similar to mouse embryos 5 and 6 days of
age are contained in the peritoneal fluid (Fig. 4).
Pierce et al. (1960) found that the embryoid bodies of the mouse
originated by sloughing of partially necrotic areas of solid intraperitoneal
growths into the ascitic fluid. There, granules developed into typical
embryoid cysts composed of elements of the three germ layers. Stevens
(1960) observed that embryoid bodies can also arise by division of
pre-existing free-floating embryoid bodies.
Pierce and Verney (1961) observed that new embryoid bodies developed from a transplanted testicular teratoma of the mouse in vitro. They
probably originated as small aggregates of embryonal carcinoma lying
superficially in a necrotic portion of an expiant that was overlaid by a
layer of visceral yolk sac. The aggregates grew and became detached
from the main growth.
Pierce and Verney (1961) observed the development of cystic embryoid
bodies from expiants of teratocarcinoma that were maintained for as
long as 5 months as organ cultures. The microscopic structure of the
tumors developed subcutaneously from expiants of embryoid bodies
in vitro for 6 months was compared to that of a series of control tumors
developed subcutaneously from embryoid bodies that had never been
in vitro. The control tumors consisted predominantly of brain tissue,
whereas the dominant tissue in the experimental tumors was striated
muscle. Almost all of these tumor strains lost their muscle-producing
ability after two or three passages subcutaneously in mice. Long after
tissue cultures had lost the pattern of the original explanted embryoid
bodies, new embryoid bodies were observed to develop in them.
It has already been mentioned that the embryoid bodies of the mouse
not only resemble normal early mouse embryos, but have similar embryonic potency. When grafted subcutaneously (Pierce and Dixon,
1959a) or into the anterior chamber of the eye (Stevens, 1960), they
develop into teratomas composed of many types of tissues.