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  • 1
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Chromaffin tissue ; Steroidogenesis ; ACTH ; Angiotensin II ; Catecholamines ; Acetylcholine ; Neonatal mallard duckling (Aves, Anatiformes)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The adrenal steroidogenic tissue of the neonatal mallard duckling is differentiated into an outer subcapsular zone where the cells contain many large lipid droplets, and an inner zone in which the cells appear to contain less lipid. The cells in both zones contain numerous mitochondria and an abundance of smooth endoplasmic reticulum, and their interdigitating plasma membranes possess many filipodia, coated pits and desmosome-like junctions. Islands of chromaffin cells are distributed throughout the steroidogenic tissue. Two types of chromaffin cell are present, one with vesicles containing densely staining material and the other more lightly staining material. Non-myelinated preganglionic fibers synapse with the chromaffin cells and the axonal terminals contain two types of dense-cored vesicles as well as acetylcholine-containing vesicles. The basal rates of corticosterone (B) and aldosterone (Aldo) release from tissue superfused with buffer containing no secretogogue were low and almost equal (B: Aldo=1.25); the corresponding rate of deoxycorticosterone (DOC) release was less than one-fortieth of the rates of B and Aldo release. The addition of 1–24 ACTH to the medium caused the rate of release of each hormone to increase as a semi-logarithmic function of the concentration and the induced increase in B release was always significantly higher than that of Aldo (B: Aldo=4.8). The corticotropin-induced rates of B and Aldo, but not DOC, release reflected do novo hormone synthesis. Norepinephrine, epinephrine and dopamine each suppressed the basal rates of B and Aldo release, but had no effect when the medium contained 1–24 ACTH. Acetylcholine (ACh) similarly suppressed the basal rates of hormone release, and neither suppressed nor enhanced the responses to medium containing 1–24 ACTH. The suppressive effects of the catecholamines and ACh were not dose-related. [Asp1, Val5] angiotensin II induced significant semi-logarithmic dose-dependent increases in Aldo synthesis but had no effect on the release of either B or DOC.
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  • 2
    ISSN: 1432-0878
    Keywords: Adrenal gland ; Cell culture ; ACTH ; Ageing ; Corticosteroid ; Cytoskeleton ; Domestic mallard, embryos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphological and functional changes associated with ageing were studied in adrenal steroidogenic cells derived from duck embryos. Cells grown for not more than three days had structural characteristics similar to their counterparts in vivo; they contained numerous lipid droplets and mitochondria, an abundant smooth edoplasmic reticulum, an even network of microtubules, and microfilaments that formed extensive and elaborate systems of parallel stress fibers. After the 3rd day of growth in culture, many of the cells started to decrease in size and become elongated; the older cells showed less well-defined actin filaments and contained elongated mitochondria, fewer lipid droplets, less smooth endoplasmic reticulum, and swollen cisternae of rough endoplasmic reticulum. The proliferative capacity of the cells was the same when they were cultured in either the presence or the absence of 1–24 ACTH. After the first day of growth in culture, the steroidogenic capacity of the cells declined and the addition of 1–24 ACTH to the growth medium did not prevent changes in their structure and function. The decline in steroidogenic capacity occurred both in terms of the amount of hormone released into the culture medium and in the ability of the cells to respond when incubated in buffer containing 1–24 ACTH. Since the basal unstimulated rates of corticosteroid production also declined as the cells aged, it is probable that the steroidogenic deficiency occurs at a site distal to the corticotropin receptor; this is also consistent with the ultrastructural observations that suggest a relationship between the morphological changes and the decline in steroidogenic capacity as the cells age.
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  • 3
    ISSN: 1432-0878
    Keywords: ACTH ; Cytochalasin ; Adrenal gland ; Actin microfilaments ; Tissue culture ; Fluorescence microscopy ; Primary culture ; Domestic mallard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Cultured steroidogenic cells derived from the adrenal glands of duck embryos were used to study changes in the distribution of actin associated with the corticotropic responsiveness. Actin-containing components were identified by rhodamine-phalloidin staining. The actin in most of the unstimulated cells occurred as stress fibers that either ran parallel throughout the cell or were present as domains of parallel fibers at angles to one another. When incubated in Krebs-Henseleit buffer containing 1–24 ACTH, the cells released approximately equal amounts of corticosterone and aldosterone. Incubation of the cells in buffer containing cytochalasin D caused the cells to lose their stress fibers, and the actin became distributed at the periphery in what appeared to be fragments of stress fibers and clumps of fibrous material in the central cytoplasm. Although cytochalasin D did not affect the basal output of corticosterone and aldosterone, the 1–24 ACTH-induced rates of both hormones were suppressed significantly. After the cells had been washed in unadulterated buffer, the normal distribution of actin stress fibers was restored and the cells responded normally when incubated in buffer containing 1–24 ACTH. These results suggest that the actin components of the cytoskeleton are important determinants of corticotropin-induced steroidogenic responsiveness.
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  • 4
    ISSN: 1432-0878
    Keywords: ACTH ; Actin ; Adrenal gland ; Cell culture ; Corticosterone ; Cytoskeleton ; Steroidogenesis ; Tubulin ; Development, ontogenetic ; Domestic mallard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cells derived from the adrenal glands of duck embryos immediately prior to hatching were grown in culture and used to study the morphological and cytoskeletal changes and steroidogenic responses induced by 1–24 ACTH. Changes in the cytoskeletal components were observed by rhodamine-phalloidin staining for actin and by staining the tubulin immunoreactive components with FITC. The cultures were comprised of a small population of chromaffin cells and a larger population of steroidogenic cells. The chromaffin cells were distinguished by their tyrosine hydroxylase immunoreactivity. The steroidogenic cells were characterized by the presence of sudanophilic lipid droplets, numerous mitochondria, abundant smooth endoplasmic reticulum, microtubules distributed as a fairly even network throughout the cytoplasm, and microfilaments that formed an extensive and elaborate system of stress fibers with many parallel arrays. The cells readily responded to stimulation with ACTH by releasing corticosterone, aldosterone and deoxycorticosterone. Stimulation with ACTH also induced changes in both the cell morphology and the cytoskeleton. Exposure of the cells to Krebs-Henseleit buffer containing 1–24 ACTH caused them to form numerous fine filopodia, to lose their stress fibers, and to form a thick ring of actin at the periphery of the cell. In addition, many cells became extremely arborized with many long branched dendritic processes. The morphological changes appeared to be related to a redistribution of the actin components, and may be explained only in part by the rounding up or retraction of the cytoplasm. The results strongly suggest an involvement of the actin components of the cytoskeleton in the steroidogenic response to corticotropic stimulation.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 258 (1989), S. 593-601 
    ISSN: 1432-0878
    Keywords: Adrenal gland ; Corticosteroid ; Steroidogenesis ; Embryogenesis ; ACTH ; Mallard duckling, Anas platyrhynchos (Aves, Anatiformes)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The differentiating nephrotome in the 10-day-old mallard duck embryo is able to synthesize corticosterone, aldosterone and deoxycorticosterone even though an adrenal anlage cannot be identified histologically until the 12th day of incubation. At this time, sudanophilic cells containing much smooth endoplasmic reticulum and numerous mitochondria with tubular cristae are located adjacent to the developing mesonephros. Chromaffm cells appear in this region on about the 14th day of embryogenesis. A discrete glandular structure containing measurable quantities of corticosteroids can be identified on the 15th day, and during the next 2 days the tissue becomes encapsulated. Concomitantly, the ACTH-inducible rates of corticosteroid hormone synthesis increase several fold. The corticotropic responsiveness of the developing adrenal steroidogenic tissue increases progressively during the remainder of embryogenesis.
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  • 6
    ISSN: 1432-0878
    Keywords: ACTH ; Adrenal gland ; Cell culture ; Corticosteroid ; Steroidogenesis ; Mallard duckling (Anas platyrhynchos)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Primary cell cultures were prepared from the adrenal glands of one-day-old mallard ducklings (Anas platyrhynchos). The cells attached equally well to uncoated plastic and glass surfaces and on surfaces that had been coated with collagen. The phase of logarithmic growth occurred between the second and the fourth day, and the cells became confluent between the fifth and the sixth day. Staining with Sudan black B and toluidine blue and viewing fixed preparations by transmission electron microscopy indicated that the cultures consisted mostly of steroidogenic cells. A smaller population of chromaffin cells was also present. Scanning electron microscopy showed that most of the cells had long filopodia, and some cells had numerous surface blebs that were interpreted as exocytotic vesicles. When incubated in Krebs-Henseleit buffer containing 1–24 ACTH the cultured cells released three corticosteroids, namely, corticosterone, aldosterone and deoxycorticosterone. These responses occurred within 15 min of exposure to medium containing 1–24 ACTH and continued throughout a 60-min period of continuous stimulation. The minimally effective concentration of 1–24 ACTH was 0.078 ng per ml (0.0234 nM) and, as the concentration was increased up to 10 ng per ml (2.99 nM), the total output of each hormone during the 60-min incubation period increased significantly according to the following semi-logarithmic relationship: Y=a+b log X, where Y=the total output of hormone, X=the concentration of 1–24 ACTH in the medium, and a=the total output of hormone when the medium contained 1.0 ng of 1–24 ACTH per ml. The total outputs of each hormone in the presence of a maximally effective concentration of 1–24 ACTH, however, were low compared to the responses of similarly stimulated tissue slices taken from the neonatal duckling. It is concluded that most of the cells comprising the confluent cultures were derived from steroidogenic cells in the neonatal adrenal. These cells appeared to retain corticotropin receptors during the course of developing into confluent monolayers, but their diminished steroidogenic capacity to respond when stimulated maximally suggests that some generational changes may have occurred.
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  • 7
    ISSN: 1432-0878
    Keywords: ACTH ; Adrenal zonation ; Birds ; Corticosterone ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary There are two regions of steroidogenic cells in the duck adrenal gland. An outer, subcapsular zone (SCZ), consisting of cells with irregularly shaped nuclei, shows relatively little smooth endoplasmic reticulum and mitochondria with shelf-like cristae. This region surrounds the inner zone (IZ) of the gland which is comprised of smaller cells with rounded nuclei, a more abundant smooth endoplasmic reticulum and mitochondria with tubular cristae. When samples of tissue from these distinct regions of the gland are superfused in vitro with media containing concentrations of 1–24 ACTH ranging from 100 to 1000 ng per ml (0.034 to 0.34 μM) the steroidogenic cells in both zones release corticosterone in a dose-dependent manner. The dose-responsiveness of both the SCZ and the IZ cells over this range is a complex quadratic function of the 1–24 ACTH concentration in the medium and the semilogarithmic linear portions of the dose-response curves are restricted to a narrow midrange of ACTH concentrations. Throughout the dose-response range, however, the steroidogenic cells of the IZ are more responsive to corticotropic stimulation than are the cells of the SCZ. The cells of the two zones are further distinguished by their responses to a challenge for a second time with medium containing 1–24 ACTH; the responses of the IZ cells to a second challenge were greater than those of the SCZ cells, and at a high concentration of ACTH the SCZ slices showed no significant second response.
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