632
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L A S N I T Z K I
creased. Thus, in the older glands the hormone directly antagonizes
the effect of the carcinogen.
3. The Effect of Sex Hormones on the Differentiation of Melanophores
Hamilton (1940) found that in skin explants from red breeds of fowls,
grown in medium without added hormones, red melanophores are
almost entirely absent, although present in large quantities in the
plumage of the adult bird. In explants from black breeds, on the other
hand, a great number of black melanophores appear, their colour
ranging from yellowish grey to black according to their stage of development. Addition of oestradiol monobenzoate, or oestradiol dibenzoate
and of testosterone propionate to the medium strikingly increased the
number of red melanophores (Hamilton, 1941). The degree of response
was unrelated to the sex of the donor. Testosterone propionate was
found to be the most potent agent. This hormone, however, failed to
promote the formation of red melanophores in explants from hybrids
of black and red breeds with a dark plumage colour in which the red
colour might have been latent, and strongly inhibited the development
of black melanophores normally seen in such cultures. Testosterone
and oestradiol monobenzoate likewise reduced the number of black
melanophores in cultures from black breeds and also slowed down their
differentiation. It is unlikely that this inhibition is related to a general
retardation of growth as it occurred in well-growing explants. It
seems, therefore, that both inhibition of black and promotion of red
melanophores must be due to a direct action of the hormones on these
elements.
4. Differential Response to Sex Hormones of Isolated Cells and Organized
Tissues
It has been shown that the effect of sex hormones on proliferation
of cell cultures—none of them derived from hormone-sensitive target
organs—was inconsistent or could be attributed to a toxic action of the
hormones at high concentrations. The response of the target organs
was, on the other hand, evoked by low doses and not only involved
cell multiplication but also stimulation of structural differentiation and
specialized functions. The question arises whether isolated cells, derived
from such target organs, retain the sensitivity of the parent tissue?
Coujard (1943) and Champy, Coujard and Demay (1950) compared
the effect of folliculin and male sex hormones on organ- and cellcultures of mammalian vagina, uterus and epididymis. Folliculin promoted keratinization in the vagina kept as an organ, but failed to do so
in sheets of pure epithelial cells obtained by subculture of the epithelium
lifted off the vagina. In the uterus, folliculin and progesterone stimulated
I L S E
L A S N I T Z K I
creased. Thus, in the older glands the hormone directly antagonizes
the effect of the carcinogen.
3. The Effect of Sex Hormones on the Differentiation of Melanophores
Hamilton (1940) found that in skin explants from red breeds of fowls,
grown in medium without added hormones, red melanophores are
almost entirely absent, although present in large quantities in the
plumage of the adult bird. In explants from black breeds, on the other
hand, a great number of black melanophores appear, their colour
ranging from yellowish grey to black according to their stage of development. Addition of oestradiol monobenzoate, or oestradiol dibenzoate
and of testosterone propionate to the medium strikingly increased the
number of red melanophores (Hamilton, 1941). The degree of response
was unrelated to the sex of the donor. Testosterone propionate was
found to be the most potent agent. This hormone, however, failed to
promote the formation of red melanophores in explants from hybrids
of black and red breeds with a dark plumage colour in which the red
colour might have been latent, and strongly inhibited the development
of black melanophores normally seen in such cultures. Testosterone
and oestradiol monobenzoate likewise reduced the number of black
melanophores in cultures from black breeds and also slowed down their
differentiation. It is unlikely that this inhibition is related to a general
retardation of growth as it occurred in well-growing explants. It
seems, therefore, that both inhibition of black and promotion of red
melanophores must be due to a direct action of the hormones on these
elements.
4. Differential Response to Sex Hormones of Isolated Cells and Organized
Tissues
It has been shown that the effect of sex hormones on proliferation
of cell cultures—none of them derived from hormone-sensitive target
organs—was inconsistent or could be attributed to a toxic action of the
hormones at high concentrations. The response of the target organs
was, on the other hand, evoked by low doses and not only involved
cell multiplication but also stimulation of structural differentiation and
specialized functions. The question arises whether isolated cells, derived
from such target organs, retain the sensitivity of the parent tissue?
Coujard (1943) and Champy, Coujard and Demay (1950) compared
the effect of folliculin and male sex hormones on organ- and cellcultures of mammalian vagina, uterus and epididymis. Folliculin promoted keratinization in the vagina kept as an organ, but failed to do so
in sheets of pure epithelial cells obtained by subculture of the epithelium
lifted off the vagina. In the uterus, folliculin and progesterone stimulated