6. ADRENAL STEROIDS AND ACTH
331
that the cells actively participate in protein synthesis. The “blown-up”
cristae of the mitochondria so characteristic of steroidogenic tissues are
conspicuously absent (Ristow and Piepho, 1963; Oguri, 1966; Fujita and
Honma, 1967; Barer and Chester Jones, 1968 ) . On embryological grounds,
too, the corpuscles of Stannius are quite distinct from steroid producing
tissues. The latter, including the adrenal cortex and gonads, arise from the
mesodermal blastema ( Witschi, 1956; Chester Jones, 1957), while the
corpuscles of Stannius are outgrowths from the pronephric duct of the
kidney (Garret, 1942; Ford, 1959; de Smet, 1962).
It may well be that certain enzymes present in the corpuscles of
Stannius can metabolize steroid precursors, as is true for the kidney and
other tissues. However, the gland is not steroidogenic in the sense
that it cannot by itself complete the conversion of cholesterol, the normal
precursor for adrenocorticosteroids in most vertebrates, to the biologically
active adrenocortical hormones. There is of course the possibility, as has
been suggested (Nandi, 1967), that the gland may store steroids. Until
the chemical nature of the corpuscular hormone is identified this problem
remains open,
111. PHYSIOLOGICAL ROLE OF THE ADRENAL
CORTICAL SECRETIONS
A. General Considerations
The problem of regulation of physiological function by hormonal
systems comprises many facets. In regard to the adrenal cortex, the type
and circulating concentration of steroid presented to the target organ
must be known. Individual steroids will probably have different activities
or potencies in their actions upon any one target organ. An investigation
thus entails identification of the target organ( s ) and a determination of the
titers of the natural hormones. Knowledge of the mechanism of the action
of the hormone gives an insight into the interrelationship between this
system of control and other systems such as other hormonal or neural
mechanisms. Finally, the regulation of the secretory rate of the hormone
must be considered. The latter involves afferent pathways which detect
the demand for the particular hormone, and this must be translated into
efferent pathways to regulate hormone secretion. One major efferent
output in the case of the adrenal cortex is of course the pituitary gland.
The question of extrapituitary control of the adrenal cortex (e.g., the
renin-angiotensin system as established for mammalian species) consti-
331
that the cells actively participate in protein synthesis. The “blown-up”
cristae of the mitochondria so characteristic of steroidogenic tissues are
conspicuously absent (Ristow and Piepho, 1963; Oguri, 1966; Fujita and
Honma, 1967; Barer and Chester Jones, 1968 ) . On embryological grounds,
too, the corpuscles of Stannius are quite distinct from steroid producing
tissues. The latter, including the adrenal cortex and gonads, arise from the
mesodermal blastema ( Witschi, 1956; Chester Jones, 1957), while the
corpuscles of Stannius are outgrowths from the pronephric duct of the
kidney (Garret, 1942; Ford, 1959; de Smet, 1962).
It may well be that certain enzymes present in the corpuscles of
Stannius can metabolize steroid precursors, as is true for the kidney and
other tissues. However, the gland is not steroidogenic in the sense
that it cannot by itself complete the conversion of cholesterol, the normal
precursor for adrenocorticosteroids in most vertebrates, to the biologically
active adrenocortical hormones. There is of course the possibility, as has
been suggested (Nandi, 1967), that the gland may store steroids. Until
the chemical nature of the corpuscular hormone is identified this problem
remains open,
111. PHYSIOLOGICAL ROLE OF THE ADRENAL
CORTICAL SECRETIONS
A. General Considerations
The problem of regulation of physiological function by hormonal
systems comprises many facets. In regard to the adrenal cortex, the type
and circulating concentration of steroid presented to the target organ
must be known. Individual steroids will probably have different activities
or potencies in their actions upon any one target organ. An investigation
thus entails identification of the target organ( s ) and a determination of the
titers of the natural hormones. Knowledge of the mechanism of the action
of the hormone gives an insight into the interrelationship between this
system of control and other systems such as other hormonal or neural
mechanisms. Finally, the regulation of the secretory rate of the hormone
must be considered. The latter involves afferent pathways which detect
the demand for the particular hormone, and this must be translated into
efferent pathways to regulate hormone secretion. One major efferent
output in the case of the adrenal cortex is of course the pituitary gland.
The question of extrapituitary control of the adrenal cortex (e.g., the
renin-angiotensin system as established for mammalian species) consti-