636
I L S E
L A S N I T Z K I
Progesterone, prolactin and hydrocortisone administered alone or
in combination were only effective if insulin was present as well.
Progesterone with insulin produced an effect similar to that of
prolactin with insulin: both hormones evoked a marked lobuloalveolar development; if combined, their action seemed to be additive.
Hydrocortisone induced a dilatation of the ducts; if combined with either
progesterone or prolactin the same effect was observed, except that
the lining epithelium was slightly higher than after hydrocortisone
and insulin alone. The best results: lobulo-alveolar development with
high secretory lining epithelium were obtained by a combination of
insulin, progesterone, prolactin and hydrocortisone (Figs. 24 and 25).
If prolactin was omitted the lining epithelium of ducts and lobules
remained low and the lumina o f ducts and end-buds became distended.
The influence of hormones during a still later stage of development
was investigated by Elias (1957, 1959) and by Rivera and Bern (1961)
who compared the hormone dependence of the early prelactating and
late prelactating organ with that of the post-lactating gland, all
derived from multiparous mice of the C 3 H / H E C R G L strain. Late
prelactating glands from mice pregnant for 14-18 days consist of welldeveloped lobuli of alveoli. The alveolar cells are large and contain
cytoplasmic vacuoles and the lumen is filled with secretory material.
Explantation into defined medium without hormones is followed by
complete degeneration of the alveoli. Addition of insulin improved the
survival of the explants, while a combination of insulin and Cortisol
completely preserved the alveolar structure; but such cultures still
showed loss of secretory activity. Cytoplasmic vacuoles were absent
and the lumina distended without secretion. If insulin was replaced
by mammotrophin the secretory activity was restored (Elias, 1959)
while a combination of somatotrophin, mammotrophin with cortisone
and insulin a c t u a l l y i n c r e a s e d it ( R i v e r a and Bern, 1961). The e a r l y
prelactating g l a n d obtained between the tenth and twelth day of
pregnancy, composed of small alveoli with narrow lumina with little
or no secretion, also became degenerate if kept in defined medium
without hormone, but the breakdown was delayed by the addition
of insulin. Maintenance of structure and stimulation of the secretory
activity were achieved by insulin and Cortisol applied with either
somatotrophin or mammotrophin or both. T o obtain this effect the
concentration of the pituitary hormones however had to be three to
four times higher than that needed to maintain the function of the
late prelactating organ.
In glands from post-lactating mice the alveoli are in different stages
of regression and the organ often consists of ducts only. In contrast to
the prelactating tissue these glands grew well with insulin alone. In
I L S E
L A S N I T Z K I
Progesterone, prolactin and hydrocortisone administered alone or
in combination were only effective if insulin was present as well.
Progesterone with insulin produced an effect similar to that of
prolactin with insulin: both hormones evoked a marked lobuloalveolar development; if combined, their action seemed to be additive.
Hydrocortisone induced a dilatation of the ducts; if combined with either
progesterone or prolactin the same effect was observed, except that
the lining epithelium was slightly higher than after hydrocortisone
and insulin alone. The best results: lobulo-alveolar development with
high secretory lining epithelium were obtained by a combination of
insulin, progesterone, prolactin and hydrocortisone (Figs. 24 and 25).
If prolactin was omitted the lining epithelium of ducts and lobules
remained low and the lumina o f ducts and end-buds became distended.
The influence of hormones during a still later stage of development
was investigated by Elias (1957, 1959) and by Rivera and Bern (1961)
who compared the hormone dependence of the early prelactating and
late prelactating organ with that of the post-lactating gland, all
derived from multiparous mice of the C 3 H / H E C R G L strain. Late
prelactating glands from mice pregnant for 14-18 days consist of welldeveloped lobuli of alveoli. The alveolar cells are large and contain
cytoplasmic vacuoles and the lumen is filled with secretory material.
Explantation into defined medium without hormones is followed by
complete degeneration of the alveoli. Addition of insulin improved the
survival of the explants, while a combination of insulin and Cortisol
completely preserved the alveolar structure; but such cultures still
showed loss of secretory activity. Cytoplasmic vacuoles were absent
and the lumina distended without secretion. If insulin was replaced
by mammotrophin the secretory activity was restored (Elias, 1959)
while a combination of somatotrophin, mammotrophin with cortisone
and insulin a c t u a l l y i n c r e a s e d it ( R i v e r a and Bern, 1961). The e a r l y
prelactating g l a n d obtained between the tenth and twelth day of
pregnancy, composed of small alveoli with narrow lumina with little
or no secretion, also became degenerate if kept in defined medium
without hormone, but the breakdown was delayed by the addition
of insulin. Maintenance of structure and stimulation of the secretory
activity were achieved by insulin and Cortisol applied with either
somatotrophin or mammotrophin or both. T o obtain this effect the
concentration of the pituitary hormones however had to be three to
four times higher than that needed to maintain the function of the
late prelactating organ.
In glands from post-lactating mice the alveoli are in different stages
of regression and the organ often consists of ducts only. In contrast to
the prelactating tissue these glands grew well with insulin alone. In