16. A C T I O N S OF H O R M O N E S
639
precancerous structures. They show the same histology as late prelactating glands but occur in otherwise inactive tissue. Both tissues
degenerate if explanted into defined medium without hormones.
A combination of hormones containing oestrogen, progesterone,
Cortisol, mammotrophin and somatotrophin was applied in a high and
a low concentration. With the higher dose prelactating glands and
hyperplastic nodules maintained their structure for 10 days and showed
greater secretory activity. With the lower hormone concentration the
nodules were well preserved for 10 days although the secretion was
much reduced; in the prelactating gland, however, the structure was
only partially maintained. After 5 days the organ showed many areas
of necrosis and after 10 days the whole of the explant had undergone
complete degeneration. Cortisol and mammotrophin seemed to be the
essential hormones in the "high" combination. Cortisol with mammotrophin and somatotrophin, or Cortisol with mammotrophin produced the
same effect as the five hormones combined; on the other hand, withdrawal of Cortisol resulted in a severe breakdown of both prelactating
glands and nodules. The terminal ducts in both tissues responded
in the same way as the alveoli, but the large ducts were maintained
in media which were inadequate and in which alveoli and terminal
ducts broke down.
The spontaneous and transplantable tumours studied consisted of
nests or strands of cells which in some regions formed alveoli with
occluded lumina and without secretory activity. The peripheral parts
of both tumours grew well in a medium without hormones but the
spontaneous tumour showed some central necrosis which was absent
from explants of the transplantable carcinomata. Addition of hormones
to the medium did not influence the growth pattern of the tumours.
Thus, the growth of tumours was largely independent of hormones
while nodules and lactating glands needed a supply of at least two
hormones for their survival and function. The nodules, however,
could be maintained by amounts of hormones which were insufficient
for the survival of the prelactating gland and could therefore be considered as intermediate between tumour and prelactating gland. This
concept agrees well with results in vivo by Bern, Nandi and DeOme
(1957) that hypophysectomy is followed by degeneration of most
nodules but not of that of spontaneous mammary tumours.
V I I . E F F E C T S OF T H Y R O X I N E A N D T R I I O D O T H Y R O N I N E
A. EFFECTS ON CELL C U L T U R E S
Early studies on the effects of thyroxine on tissue cultures were mainly
concerned with the action of the hormone on the proliferation of
639
precancerous structures. They show the same histology as late prelactating glands but occur in otherwise inactive tissue. Both tissues
degenerate if explanted into defined medium without hormones.
A combination of hormones containing oestrogen, progesterone,
Cortisol, mammotrophin and somatotrophin was applied in a high and
a low concentration. With the higher dose prelactating glands and
hyperplastic nodules maintained their structure for 10 days and showed
greater secretory activity. With the lower hormone concentration the
nodules were well preserved for 10 days although the secretion was
much reduced; in the prelactating gland, however, the structure was
only partially maintained. After 5 days the organ showed many areas
of necrosis and after 10 days the whole of the explant had undergone
complete degeneration. Cortisol and mammotrophin seemed to be the
essential hormones in the "high" combination. Cortisol with mammotrophin and somatotrophin, or Cortisol with mammotrophin produced the
same effect as the five hormones combined; on the other hand, withdrawal of Cortisol resulted in a severe breakdown of both prelactating
glands and nodules. The terminal ducts in both tissues responded
in the same way as the alveoli, but the large ducts were maintained
in media which were inadequate and in which alveoli and terminal
ducts broke down.
The spontaneous and transplantable tumours studied consisted of
nests or strands of cells which in some regions formed alveoli with
occluded lumina and without secretory activity. The peripheral parts
of both tumours grew well in a medium without hormones but the
spontaneous tumour showed some central necrosis which was absent
from explants of the transplantable carcinomata. Addition of hormones
to the medium did not influence the growth pattern of the tumours.
Thus, the growth of tumours was largely independent of hormones
while nodules and lactating glands needed a supply of at least two
hormones for their survival and function. The nodules, however,
could be maintained by amounts of hormones which were insufficient
for the survival of the prelactating gland and could therefore be considered as intermediate between tumour and prelactating gland. This
concept agrees well with results in vivo by Bern, Nandi and DeOme
(1957) that hypophysectomy is followed by degeneration of most
nodules but not of that of spontaneous mammary tumours.
V I I . E F F E C T S OF T H Y R O X I N E A N D T R I I O D O T H Y R O N I N E
A. EFFECTS ON CELL C U L T U R E S
Early studies on the effects of thyroxine on tissue cultures were mainly
concerned with the action of the hormone on the proliferation of