610
ILSE L A S N I T Z K I
Under all three conditions the whole cortical extract caused a significantly greater distension of the kidney tubules as compared with the
controls, but compound E was far more effective than the whole
compound. It produced marked distension after immersion with
concentrations ranging from 1 : 100,000-1 :500,000 and incubation
with a concentration of 1 : 100,000 still produced a considerable effect.
On the other hand, compound A had no influence on the secretory
activity in dilutions below 1 :50,000. The relative ineffectiveness of
compound A on kidney secretion is in contrast to its action on the
isolated frog hind-limb where it reduces oedema formation (Hyman
and Chambers, 1943). The effect of the two compounds on two different
processes—fluid transfer across a vascular wall and active secretory
activity—may in the author's view be related to their different physiological functions. Thus compound A is known to regulate the metabolism of inorganic salts, while compound E enhances carbohydrate
metabolism.
D. EFFECTS ON SKIN
Fell (1962) studied the effect of hydrocortisone on the development
of the epidermis in explants from chick and rat embryos. Skin from
9-day chick embryos forms squamous keratinizing epithelium within
1 week's growth, while the feather germs elongate appreciably. In
explants grown with 7-5 /xg/ml of hydrocortisone the elongation ofthe
feather germs was arrested and the keratinization of the epidermis
promoted. Skin from 18-day rat embryos responded in a similar way.
After 4 days' growth keratinization was more advanced in treated
explants, but 2 days later there was no difference between experimental
and control cultures, which suggests that the hormone merely accelerates the development of keratinization but does not increase its final
amount.
Cortisone and hydrocortisone are known to have a beneficial effect
on various types of skin eruptions and also on burns from u.v. rays.
This effect may be mediated through the vascular system, or be a
general systemic effect or may be due to a direct action on the damaged
tissue. This problem was studied by Weissmann and Fell (1962) in
organ cultures of foetal rat skin, grown with and without hydrocortisone.
The explants were exposed to u.v. from an unfiltered lamp at 2 days'
growth. Irradiation was followed by a breakdown of epidermis and
dermis in both sets of cultures. But the damage was more severe in
cultures kept without the hormone. In control medium, the epidermis
largely disintegrated and became detached and formed a blister above
the dermis, in which tissue both cells and intercellular material were
ILSE L A S N I T Z K I
Under all three conditions the whole cortical extract caused a significantly greater distension of the kidney tubules as compared with the
controls, but compound E was far more effective than the whole
compound. It produced marked distension after immersion with
concentrations ranging from 1 : 100,000-1 :500,000 and incubation
with a concentration of 1 : 100,000 still produced a considerable effect.
On the other hand, compound A had no influence on the secretory
activity in dilutions below 1 :50,000. The relative ineffectiveness of
compound A on kidney secretion is in contrast to its action on the
isolated frog hind-limb where it reduces oedema formation (Hyman
and Chambers, 1943). The effect of the two compounds on two different
processes—fluid transfer across a vascular wall and active secretory
activity—may in the author's view be related to their different physiological functions. Thus compound A is known to regulate the metabolism of inorganic salts, while compound E enhances carbohydrate
metabolism.
D. EFFECTS ON SKIN
Fell (1962) studied the effect of hydrocortisone on the development
of the epidermis in explants from chick and rat embryos. Skin from
9-day chick embryos forms squamous keratinizing epithelium within
1 week's growth, while the feather germs elongate appreciably. In
explants grown with 7-5 /xg/ml of hydrocortisone the elongation ofthe
feather germs was arrested and the keratinization of the epidermis
promoted. Skin from 18-day rat embryos responded in a similar way.
After 4 days' growth keratinization was more advanced in treated
explants, but 2 days later there was no difference between experimental
and control cultures, which suggests that the hormone merely accelerates the development of keratinization but does not increase its final
amount.
Cortisone and hydrocortisone are known to have a beneficial effect
on various types of skin eruptions and also on burns from u.v. rays.
This effect may be mediated through the vascular system, or be a
general systemic effect or may be due to a direct action on the damaged
tissue. This problem was studied by Weissmann and Fell (1962) in
organ cultures of foetal rat skin, grown with and without hydrocortisone.
The explants were exposed to u.v. from an unfiltered lamp at 2 days'
growth. Irradiation was followed by a breakdown of epidermis and
dermis in both sets of cultures. But the damage was more severe in
cultures kept without the hormone. In control medium, the epidermis
largely disintegrated and became detached and formed a blister above
the dermis, in which tissue both cells and intercellular material were