THE BIOLOGY OF TERATOMAS
23
chromosomes. The Y chromosome is approximately the size of the smallest pair of autosomes. Male cells have three smallest chromosomes and
female cells have two. Occasionally male cells are misdiagnosed. Stevens
and Bunker (1964) used this method to determine the sex of early
primary testicular teratomas. Eighty-seven of 89 teratomatous cells
showed the male karyotype. This indicates that probably all cells in
early testicular teratomas of strain 129 mice are male, supporting the
hypothesis that the tumors are derived from diploid primordial germ
cells.
XII. Embryoid Bodies
In 1936 and 1939 Peyron et al. described small structures morphologically similar to early human embryos in a human testicular teratoma.
These embryoid bodies, like human blastocysts, were composed of ectodermal and endodermal vesicles with mesodermal cells between them.
In spite of severe criticism, Peyron et al. (1936, 1939) maintained that
these structures were homologous to normal human embryos. He had the
audacity to describe this tumor as an atlas of presomite embryology
that was more complete than any other source at that time (Masson,
1956).
Since Peyron's (1936-1939) original discovery several investigators
have observed embryoid bodies in human testicular tumors of germ cell
origin (Melicow, 1940, 1955; Nicod, 1945; Friedman and Moore, 1946;
Friedman, 1959; Teilum, 1950; Dixon and Moore, 1952, 1953; Masson,
1956; Simard, 1957; Gaillard, 1957, 1958; Cabanne, 1957; Evans, 1957;
Marin-Padilla, 1965), and in metastatic and transplanted testicular teratomas of the mouse (Stevens, 1958, 1959, 1960; Pierce et al., 1959a,
1960).
Simard (1957) described the first embryoma of the ovary to have
embryoid bodies. This tumor contained literally hundreds of embryoid
formations. The greater part of the tumor was made up of a mixture
of almost all the tissues of the human body. The embryoid bodies illustrated in Simard's paper look much like those described in testicular
teratomas by Peyron and others. They closely mimicked normal human
embryos. Simard believed that the embryoid bodies occupied the place
of the primordial follicles and suggested that they arose from recent and
simultaneous proliferation of a whole group of ova. It is known in the
mouse (Pierce and Verney, 1961; Stevens, 1962) that teratomatous
embryoid bodies do not arise directly from the germ cells, but rather
from the undifferentiated embryonal (embryonal carcinoma) stem cells
of the tumor.
23
chromosomes. The Y chromosome is approximately the size of the smallest pair of autosomes. Male cells have three smallest chromosomes and
female cells have two. Occasionally male cells are misdiagnosed. Stevens
and Bunker (1964) used this method to determine the sex of early
primary testicular teratomas. Eighty-seven of 89 teratomatous cells
showed the male karyotype. This indicates that probably all cells in
early testicular teratomas of strain 129 mice are male, supporting the
hypothesis that the tumors are derived from diploid primordial germ
cells.
XII. Embryoid Bodies
In 1936 and 1939 Peyron et al. described small structures morphologically similar to early human embryos in a human testicular teratoma.
These embryoid bodies, like human blastocysts, were composed of ectodermal and endodermal vesicles with mesodermal cells between them.
In spite of severe criticism, Peyron et al. (1936, 1939) maintained that
these structures were homologous to normal human embryos. He had the
audacity to describe this tumor as an atlas of presomite embryology
that was more complete than any other source at that time (Masson,
1956).
Since Peyron's (1936-1939) original discovery several investigators
have observed embryoid bodies in human testicular tumors of germ cell
origin (Melicow, 1940, 1955; Nicod, 1945; Friedman and Moore, 1946;
Friedman, 1959; Teilum, 1950; Dixon and Moore, 1952, 1953; Masson,
1956; Simard, 1957; Gaillard, 1957, 1958; Cabanne, 1957; Evans, 1957;
Marin-Padilla, 1965), and in metastatic and transplanted testicular teratomas of the mouse (Stevens, 1958, 1959, 1960; Pierce et al., 1959a,
1960).
Simard (1957) described the first embryoma of the ovary to have
embryoid bodies. This tumor contained literally hundreds of embryoid
formations. The greater part of the tumor was made up of a mixture
of almost all the tissues of the human body. The embryoid bodies illustrated in Simard's paper look much like those described in testicular
teratomas by Peyron and others. They closely mimicked normal human
embryos. Simard believed that the embryoid bodies occupied the place
of the primordial follicles and suggested that they arose from recent and
simultaneous proliferation of a whole group of ova. It is known in the
mouse (Pierce and Verney, 1961; Stevens, 1962) that teratomatous
embryoid bodies do not arise directly from the germ cells, but rather
from the undifferentiated embryonal (embryonal carcinoma) stem cells
of the tumor.