6 0 6
I L S E
L A S N I T Z K I
ing and invites the speculation whether the other hormones released
by the gland into the medium increase or modify the activity of the
gonadotrophins. This could be decided by applying the latter in various
combinations with A C T H , thyrotrophin and growth hormone to the
ovary in culture.
The failure to obtain stimulation in mouse ovaries confronted with
anterior pituitary fragments (Franke, 1946, 1948/49) is probably due
to differences in culture technique and in particular to the use of natural
medium, which, unlike synthetic media, contains small amounts of
hormones which may mask the activity of the gonadotrophins in the
experimental cultures.
2. Effects of Anterior Pituitary on Testes
Moszkowska (1956) showed that the formation of seminiferous tubules
was considerably promoted in embryonic-chick testes grown in contact
with anterior pituitary tissue. Both testes and pituitary were derived
from 16-17-day embryos and grown by the method of Wolff and Haffen
(1952) in a denned medium to which only small quantities of embryo
extract had been added. After 3 days in vitro, the number and size of
the tubules were increased and mitoses among the spermatogonia were
three to four times as numerous as in the controls. The author compared
the effectiveness of the whole pituitary with that of its caudal and
cephalic parts and found that the caudal parts had no significant
influence on testicular development, while the majority of testes exposed to the cephalic part displayed a very marked stimulation. The
greater effectiveness of the cephalic part could be correlated with the
presence of PAS-positive cells which were absent from the caudal zone.
This indicates that in the chick the production of gonadotrophins
occurs mainly in the cephalic region and that the PAS-positive cells
are intimately connected with it.
3. Summary
Thus thyrotrophin and A C T H directly produce characteristic
changes in their target organs: stimulation of colloid formation in the
thyroid gland and increase of corticosteroid production in the adrenals.
These changes were identical in cultures exposed to the hormone
preparations and in explants grown in close contact with the anterior
pituitary, a result which suggests that the hypophysis continues to
elaborate and release hormones in vitro. In contrast, the effect of the
follicle-stimulating hormones on the ovary is much less marked than
that seen after contact with the pituitary. This indicates that under the
experimental conditions the other hormones released by the pituitary
may be synergists to the gonadotrophins and enhance their action.
I L S E
L A S N I T Z K I
ing and invites the speculation whether the other hormones released
by the gland into the medium increase or modify the activity of the
gonadotrophins. This could be decided by applying the latter in various
combinations with A C T H , thyrotrophin and growth hormone to the
ovary in culture.
The failure to obtain stimulation in mouse ovaries confronted with
anterior pituitary fragments (Franke, 1946, 1948/49) is probably due
to differences in culture technique and in particular to the use of natural
medium, which, unlike synthetic media, contains small amounts of
hormones which may mask the activity of the gonadotrophins in the
experimental cultures.
2. Effects of Anterior Pituitary on Testes
Moszkowska (1956) showed that the formation of seminiferous tubules
was considerably promoted in embryonic-chick testes grown in contact
with anterior pituitary tissue. Both testes and pituitary were derived
from 16-17-day embryos and grown by the method of Wolff and Haffen
(1952) in a denned medium to which only small quantities of embryo
extract had been added. After 3 days in vitro, the number and size of
the tubules were increased and mitoses among the spermatogonia were
three to four times as numerous as in the controls. The author compared
the effectiveness of the whole pituitary with that of its caudal and
cephalic parts and found that the caudal parts had no significant
influence on testicular development, while the majority of testes exposed to the cephalic part displayed a very marked stimulation. The
greater effectiveness of the cephalic part could be correlated with the
presence of PAS-positive cells which were absent from the caudal zone.
This indicates that in the chick the production of gonadotrophins
occurs mainly in the cephalic region and that the PAS-positive cells
are intimately connected with it.
3. Summary
Thus thyrotrophin and A C T H directly produce characteristic
changes in their target organs: stimulation of colloid formation in the
thyroid gland and increase of corticosteroid production in the adrenals.
These changes were identical in cultures exposed to the hormone
preparations and in explants grown in close contact with the anterior
pituitary, a result which suggests that the hypophysis continues to
elaborate and release hormones in vitro. In contrast, the effect of the
follicle-stimulating hormones on the ovary is much less marked than
that seen after contact with the pituitary. This indicates that under the
experimental conditions the other hormones released by the pituitary
may be synergists to the gonadotrophins and enhance their action.