16.
A C T I O N S O F
H O R M O N E S
617
in arrest of cells in metaphase. A similar deleterious effect on mitosis
was noticed in chick-heart fibroblasts grown in the presence of diethylstilboestrol and oestradiol (Lettre, 1943). Concentrations of 40-100
/xg/ml of medium produced an arrest of mitotic cells in metaphase
while higher doses (100-200 /xg/ml) caused a severe growth inhibition.
It is probable that the growth inhibition and interference with
mitosis seen in so many different cells are due to a non-specific toxic
effect of the hormones and are not related to their physiological
function.
Studies on the effects of sex hormones on their target organs grown
in vitro as organ cultures indicate a specific action on the tissues at
much lower concentrations.
B . E F F E C T S
O N E M B R Y O N I C
D E V E L O P M E N T
I N O R G A N
C U L T U R E S
Experiments suggest that the development of male accessory reproductive organs during foetal life depends on testicular hormones.
Raynaud and Frilly (1947, 1950) reported that the accessory reproductive glands of the rat are smaller or absent after destruction of the
testes by X-rays, and Jost and Bergerard (1949) and Jost and Bozic
(1951) describe retrogression of the Wolffian ducts of foetal rats in
culture.
This theory was put to the test by Price and Pannabecker (1956)
who studied the role of the sex hormones and of the testis in the development of the reproductive tracts from rat embryos. The tracts removed
from rat embryos 15-18 days after copulation, consisting of genital
tubercle, posterior urogenital sinus and Wolffian and Miillerian ducts,
were explanted with either both testes or one, without testes, with
ovaries or with addition of either testosterone propionate or oestradiol
to the culture medium (Fig. 8).
In cultures containing both testes or one, the Wolffian ducts persisted as continuous tubes and developed primordia of seminal vesicles
and prostatic buds. With one exception, this effect was similar in
explants from all ages, but in tracts from older embryos spread out
into a V-shape and explanted with one testis the maintenance of the
duct depended on its distance from the testis.
Removal of testes, or their substitution by ovaries, caused a reduction
of the diameter of the duct with loss of the lumen, shedding of the
lining epithelium and degeneration of the surrounding sheath of
mesenchyme. This regression could be prevented by addition of testosterone propionate to the medium.
Addition of oestradiol led to a regression of the Wolffian ducts in
X *
A C T I O N S O F
H O R M O N E S
617
in arrest of cells in metaphase. A similar deleterious effect on mitosis
was noticed in chick-heart fibroblasts grown in the presence of diethylstilboestrol and oestradiol (Lettre, 1943). Concentrations of 40-100
/xg/ml of medium produced an arrest of mitotic cells in metaphase
while higher doses (100-200 /xg/ml) caused a severe growth inhibition.
It is probable that the growth inhibition and interference with
mitosis seen in so many different cells are due to a non-specific toxic
effect of the hormones and are not related to their physiological
function.
Studies on the effects of sex hormones on their target organs grown
in vitro as organ cultures indicate a specific action on the tissues at
much lower concentrations.
B . E F F E C T S
O N E M B R Y O N I C
D E V E L O P M E N T
I N O R G A N
C U L T U R E S
Experiments suggest that the development of male accessory reproductive organs during foetal life depends on testicular hormones.
Raynaud and Frilly (1947, 1950) reported that the accessory reproductive glands of the rat are smaller or absent after destruction of the
testes by X-rays, and Jost and Bergerard (1949) and Jost and Bozic
(1951) describe retrogression of the Wolffian ducts of foetal rats in
culture.
This theory was put to the test by Price and Pannabecker (1956)
who studied the role of the sex hormones and of the testis in the development of the reproductive tracts from rat embryos. The tracts removed
from rat embryos 15-18 days after copulation, consisting of genital
tubercle, posterior urogenital sinus and Wolffian and Miillerian ducts,
were explanted with either both testes or one, without testes, with
ovaries or with addition of either testosterone propionate or oestradiol
to the culture medium (Fig. 8).
In cultures containing both testes or one, the Wolffian ducts persisted as continuous tubes and developed primordia of seminal vesicles
and prostatic buds. With one exception, this effect was similar in
explants from all ages, but in tracts from older embryos spread out
into a V-shape and explanted with one testis the maintenance of the
duct depended on its distance from the testis.
Removal of testes, or their substitution by ovaries, caused a reduction
of the diameter of the duct with loss of the lumen, shedding of the
lining epithelium and degeneration of the surrounding sheath of
mesenchyme. This regression could be prevented by addition of testosterone propionate to the medium.
Addition of oestradiol led to a regression of the Wolffian ducts in
X *