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  • 1
    Electronic Resource
    Electronic Resource
    The fine structure of the hypothalamic secretory neurons of the White-crowned Sparrow, Zonotrichia leucophrys gambelii (Passeriformes: Fringillidae) (1976)
    Springer
    Cell & tissue research 165 (1976), S. 415-434 
    Details
    ISSN: 1432-0878
    Keywords: Rostral hypothalamus ; Secretory neurons ; Magnocellular and parvocellular systems ; Ultrastructure ; Zonotrichia leucophrys gambelii (Aves)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structures of the neurons and neuropils of the magnocellular supraoptic nucleus and the parvocellular nuclei of the rostral hypothalamus, including the suprachiasmatic and medial, lateral and periventricular preoptic nuclei, and the neuronal apparatus of the organum vasculosum laminae terminalis, have been examined in the male White-crowned Sparrow, Zonotrichia leucophrys gambelii, by correlated light and electron microscopy. The magnocellular supraoptic nucleus is characterized by large neurosecretory perikarya which contain a well developed Golgi complex and densecored granules 1,500–2,200 Å in diameter. The neuropil displays axons, dendrites and glial fibers. Some axonal profiles contain dense-cored vesicles 800–1,000 Å in diameter and clear vesicles 500 Å in diameter. Axo-somatic and axo-dendritic synapses are conspicuous in this nuclear region. The suprachiasmatic nucleus is characterized by an accumulation of small neurons with moderately developed cellular organelles and some dense-cored granules, approximately 1,000 Å in diameter. The profiles of axons within the neuropil contain dense-cored granules 800–1,000 Å in diameter and clear vesicles 500 Å in diameter. The neurons of the medial preoptic nucleus are relatively large and exhibit well developed cellular organelles and dense-cored granules 1,300 to 1,500 Å in diameter. Granular materials are formed within the Golgi complex. The medial preoptic nucleus is rich in secretory perikarya. Occasionally, neurons with granules 1,500–2,200 Å in diameter are encountered in the lateral preoptic and periventricular preoptic nuclei. They may be considered as scattered elements of the magnocellular (supraoptic and paraventricular) system. The organum vasculosum laminae terminalis consists of three layers, i.e., ependymal, internal and external zones, and exhibits a vascular arrangement similar to that of the median eminence. The perikarya of the parvocellular neurons and their axons in the internal zone contain numerous secretory granules ranging from 1,300 to 1,500 Å in diameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224473
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  • 2
    Electronic Resource
    Electronic Resource
    Sir Francis Knowles (1974)
    Springer
    Cell & tissue research 152 (1974), S. i 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224206
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  • 3
    Electronic Resource
    Electronic Resource
    The fine structure of the hypothalamic secretory neurons of the White-crowned Sparrow, Zonotrichia leucophrys gambelii (Passeriformes: Fringillidae) (1975)
    Springer
    Cell & tissue research 162 (1975), S. 419-438 
    Details
    ISSN: 1432-0878
    Keywords: Infundibular (tuberal) nucleus ; Secretory neurons ; Ependyma ; Zonotrichia leucophrys gambelii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the parvocellular tuberal nuclei and that of the ependyma bordering the third ventricle in the basal hypothalamus of the White-crowned Sparrow, Zonotrichia leucophrys gambelii, have been investigated. Photoperiodically stimulated birds have been compared with birds held on short days. The perikarya of the neurons of the basal infundibular (tuberal) nucleus, and in part, of the more dorsal layers, contain dense-cored granules (1000–1500 Å). The granules in the anterior part of the nucleus are somewhat larger than those of the posterior part. The synapses and the synaptic relationships of these cells are described. The single-layered ependyma of the third ventricle in the basal hypothalamus may be divided into the dorsal typical ependyma, the ventrolateral “glandular” ependyma, and the ventral “glandular” ependyma. Cells of the ventral ependyma lack apical cilia but bear a few microvillous processes. They have well-developed Golgi apparatus, conspicuous polysomes, and frequently dense, irregularly-shaped granules. Basal cytoplasmic processes extend ventrally to the outer surface of the median eminence. Photoperiodic stimulation appears to increase the numbers of apical protrusions of the cells in the ventral glandular ependyma and to cause an increase in size of the nerve cells of the basal infundibular nucleus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209344
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  • 4
    Electronic Resource
    Electronic Resource
    Fluorescence microscopy of neurons containing primary catecholamines in the ventral hypothalamus of the white-crowned sparrow, Zonotrichia leucophrys gambelii (1973)
    Springer
    Cell & tissue research 141 (1973), S. 1-17 
    Details
    ISSN: 1432-0878
    Keywords: Monoamine fluorophores ; Avian tubero-infundibular system ; Tuberal nuclei ; Median eminence ; White-crowned Sparrow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ventral hypothalamus of White-crowned Sparrows, Zonotrichia leucophrys gambelii, was examined for primary catecholamines with the fluorescence technique of Falck-Hillarp and Owman. Photorefractory and photosensitive birds, photoperiodically stimulated and non-stimulated, were used. Four groups of catecholaminergic fibers were demonstrated: (1) afferent fibers of extra-hypothalamic origin to the infundibular nucleus where there are extensive synaptic contacts with non-fluorescent perikarya; (2) fibers apparently extending ventrally from an area with fluorescent perikarya in the vicinity of the paraventricular organ to the infundibular nucleus via the stratum cellulare internum and lateral pathways; (3) afferent fibers to the subependymal layer of the median eminence; and (4) afferent fibers to the zona externa of the median eminence. Fluorescent fibers that pass transversely through the median eminence may be derived from any of the last three categories. It appears that the fibers of the zona externa (4) are not derived to any appreciable extent from those of the subependymal layer (3). Because fluorescent perikarya could not be demonstrated in the infundibular nucleus no conclusion can be reached with respect to this nucleus as an origin for fibers (3) and (4). Diurnal cycles in the number of fluorescent terminals observable and in the intensity of the fluorescence in the palisade layer in photosensitive birds subjected to different photoperiodic regimes, in castrates, and in photorefractory birds are described tentatively on the basis of subjective assessments. Some possible implications of the differences are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307393
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  • 5
    Electronic Resource
    Electronic Resource
    The hypothalamic neurosecretory system of Coturnix coturnix japonica (1963)
    Springer
    Cell & tissue research 61 (1963), S. 688-709 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The neurosecretory cells of Coturnix coturnix japonica occur in two areas, the supraoptic nucleus and the paraventricular nucleus. These nuclear areas consist of a series of extended groups of cells (divisions) that are interconnected through irregular chains of neurosecretory cells. The paraventricular nucleus is large and well-developed. 2. Morphologically the neurosecretory cells vary extensively even in normal or control birds. There may by indistinct, small cells with very little neurosecretory material or relatively large cells filled with homogeneous neurosecretory material. In the latter the initial sections of axons are frequently conspicuous because of the presence of neurosecretory granules. The large paraventricular nucleus is striking because of its very intense neurosecretory activity. The initial part of the neurosecretory tract is clearly evident because of stainable neurosecretory substance. 3. In addition to the accumulation of neurosecretory material in the neural lobe there is a second storage site in the zona externa of the median eminence. 4. When NaCl solution is used for drinking fluid the neurosecretory cells are activated. With NaCl concentrations of 0.1–0.15 M only a mild enlargement of these cells occurs and the amount neurosecretory material in the neural lobe is only gradually decreased. However, with 0.2–0.25 M there are significant changes. The neurosecretory cells attain a very marked enlargement with the neurosecretory material being in the form of fine granules. Simultaneously there is a marked depletion of neurosecretory material in the posterior lobe. 5. When the neurosecretory material of the posterior lobe is depleted because of the drinking of NaCl solutions of 0.2–0.25 M, the neurosecretory material in the zona externa of the median eminence appears to be unaffected. In contrast to the complete depletion of neurosecretory material in the neurosecretory pathway leading to the neural lobe, the fiber bundles leading to the zona externa contain a significant amount of neurosecretory material. 6. It is not possible, on the basis of this investigation, to indicate the relative participation of axons from the supraoptic nucleus and paraventricular nucleus with respect to the median eminence and neural lobe. 7. The functional significance of individual divisions of neurosecretory nuclei is still unknown. The higher concentrations of NaCl used in our experiments stimulated all parts of the neurosecretory nuclei. What significance can be attached to certain regional differences in activity in untreated quail or in experiments with low concentrations of NaCl, is still not clear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00342619
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  • 6
    Electronic Resource
    Electronic Resource
    Fine structure of the vessels of the hypophysial portal system of the White-crowned Sparrow, Zonotrichia leucophrys gambelii (1970)
    Springer
    Cell & tissue research 106 (1970), S. 155-174 
    Details
    ISSN: 1432-0878
    Keywords: Hypophysial portal system Zonotrichia leucophrys gambelii (Aves, Passeriformes) ; Fine structure ; Control of the pars distalis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The angioarchitecture of the hypophysial portal system of the White-crowned Sparrow, Zonotrichia leucophrys gambelii, was investigated by electron microscopy in conjunction with light microscopy of serial thick sections. The small arteries or arterioles supplying the primary capillary plexus of the median eminence have the typical form of arterioles. The vessels of the primary capillary plexus, on the surface of the median eminence, with their many fenestrations and pinocytotic vesicles, are typical of the form of capillary usually found in other endocrine organs. The portal vessels in the pars tuberalis have wide perivascular spaces between the basement membrane of the endothelium and that of parenchymal lobules of the pars tuberalis. These perivascular spaces are occupied usually by the perivascular cells, but sometimes contain erythrocytes. The endothelial cells of the portal vessels often protrude into vascular lumen giving the appearance of valve-like structures. These may have a role in the regulation of blood flow. The endothelial cells of the portal vessels are invested by a definitive basement membrane and by the cytoplasm of pericytes which are oriented spirally to the longitudinal axes of the vessels. The pericytes may have a function in the mechanical support of the vascular wall and a contractile function that might regulate the flow rate of blood.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335735
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  • 7
    Electronic Resource
    Electronic Resource
    Acetylcholinesterase-containing nerve cells in the pineal complex and subcommissural area of the frogs, Rana ridibunda and Rana esculenta (1974)
    Springer
    Cell & tissue research 154 (1974), S. 423-442 
    Details
    ISSN: 1432-0878
    Keywords: Pineal complex ; Anura ; Acetylcholinesterase reaction ; Neurons (Cell types) ; Axonal projections
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In Rana esculenta and Rana ridibunda the frontal organ and the pineal organ (epiphysis cerebri) form a pineal complex. Approximately 60 nerve cells of the frontal organ and 220–320 nerve cells of the pineal organ display a positive acetylcholinesterase reaction (Karnovsky and Roots, 1964). The dorsal wall of the pineal organ is considerably richer in acetylcholinesterase-positive neurons than the ventral wall (ratio 3∶1); a group of unusually large-sized nerve cells occurs in the rostral portion of the frog pineal. Two different types of nerve cells were observed in the pineal complex: multipolar and pseudounipolar elements. The former are embedded in the pineal parenchyma and their processes penetrate radially into the plexiform layer, whereas the latter are distributed along the roots of the pineal tract near the basal lamina. The ratio of the multipolar to pseudounipolar neurons is 1∶4 for the frontal organ and 3∶5 for the pineal organ. The multipolar elements may be interneurons; the pseudouni-polar cells send one of their processes into the pineal tract. At the caudal end of the pineal organ 30–50 unipolar nerve cells are clustered in juxtaposition with the pineal tract, and other 30–50 unipolar neurons are scattered along the basis of the subcommissural organ. Some of these nerve cells emit their processes toward the mesencephalon and others toward the pineal organ via the pineal tract. The results are discussed with respect to previous physiological and morphological findings on the pineal complex of Anura.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219666
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  • 8
    Electronic Resource
    Electronic Resource
    Comparative immunocytochemical study of the subcommissural organ (1984)
    Springer
    Cell & tissue research 237 (1984), S. 427-441 
    Details
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Reissner's fiber ; Ependyma ; Secretory process ; Comparative analysis ; Immunocytochemistry ; Vertebrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The subcommissural organs (SCO) of 76 specimens belonging to 25 vertebrate species (amphibians, reptiles, birds, mammals) were studied by use of the immunoperoxidase procedure. The primary antiserum was obtained by immunizing rabbits with bovine Reissner's fiber (RF) extracted in a medium containing EDTA, DTT and urea. Antiserum against an aqueous extract of RF was also produced. The presence of immunoreactive material in cell processes and endings was regarded as an indication of a possible route of passage. Special attention was paid to the relative development of the ventricular, leptomeningeal and vascular pathways established by immunoreactive structures. The SCO of submammalian species is characterized by (i) a conspicuous leptomeningeal connection established by ependymal cells, (ii) scarce or missing hypendymal cells, and (iii) a population of ependymal cells establishing close spatial contacts with blood vessels. The SCO of most mammalian species displays the following features: (i) ependymal cells lacking immunoreactive long basal processes, (ii) hypendymal secretory cells occurring either in a scattered arrangement or forming clusters, (iii) an occasional leptomeningeal connection provided by hypendymal cells, and (iv) in certain species numerous contacts of secretory cells with blood vessels. In the hedgehog immunoreactive material was missing in the ependymal formation of the SCO, but present in hypendymal cells and in the choroid plexuses. The SCO of several species of New-and Old-World monkeys displayed immunoreactive material, whereas that of anthropoid apes (chimpanzee, orangutan) and man was completely negative with the antisera used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228427
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  • 9
    Electronic Resource
    Electronic Resource
    Spatial and structural interrelationships between secretory cells of the subcommissural organ and blood vessels (1984)
    Springer
    Cell & tissue research 237 (1984), S. 443-449 
    Details
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Ependyma ; Comparative aspects ; Immunocytochemistry ; Secretory process ; Blood vessels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In 76 specimens (amphibians, reptilians, mammals) belonging to 25 different vertebrate species, the region of the subcommissural organ (SCO) was investigated with the use of a primary antiserum raised against an extract of bovine Reissner's fiber+the immunoperoxidase procedure according to Sternberger et al. (1970). In the SCO of a toad (Bufo arenarum) and several species of reptiles (lacertilians, ophidians, crocodilians), the ependymal cells were the only type of secretory cell displaying vascular contacts, whereas in mammals ependymal and hypendymal cells established intimate spatial contacts with blood vessels. In Bufo arenarum, but especially in the reptilian species examined, the ependymo-vascular relationship was exerted by a population of ependymal cells having a rather constant location within the SCO and projecting to capillaries that showed a remarkably constant pattern of anatomical distribution. In the SCO of mammals the modality and degree of the structural relationships between secretory cells and blood vessels varied greatly from species to species. In the SCO of the armadillo and dog the secretory tissue was organized as a thick, highly vascularized layer with most of the cells oriented toward the capillaries. A rather opposite situation was found in the SCO of New-and Old-World monkeys, where vascular contacts were restricted to a few ependymal cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228428
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  • 10
    Electronic Resource
    Electronic Resource
    Immunocytochemical and electron-microscopic investigations of the pineal organ in adult agamid lizards, Uromastix hardwicki (1987)
    Springer
    Cell & tissue research 250 (1987), S. 571-578 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ ; Modified photoreceptor cells ; Secretory activity ; Interstitial cells ; Opsin-like immunoreactivity ; S-antigen-like immunoreactivity ; Uromastix hardwicki (Lacertilia)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Lacertilian species display a remarkable diversity in the organization of the neural apparatus of their pineal organ (epiphysis cerebri). The occurrence of immunoreactive S-antigen and opsin was investigated in the retina and pineal organ of adult lizards, Uromastix hardwicki. In this species, numerous retinal photoreceptors displayed S-antigen-like immunoreactivity, whereas only very few pinealocytes were labeled. Immunoreactive opsin was found neither in retinal photoreceptors nor in pinealocytes. Electron microscopy showed that all pinealocytes of Uromastix hardwicki resemble modified pineal photoreceptors. A peculiar observation is the existence of a previously undescribed membrane system in the inner segments of these cells. It is evidently derived from the rough endoplasmic reticulum but consists of smooth membranes. The modified pineal photoreceptor cells of Uromastix hardwicki were never seen to establish synaptic contacts with somata or dendrites of intrapineal neurons, which are extremely rare. Vesiclecrowned ribbons are prominent in the basal processes of the receptor cells, facing the basal lamina or establishing receptor-receptor and receptor-interstitial type synaptoid contacts. Dense-core granules (60–250 nm in diameter) speak in favor of a secretory activity of the pinealocytes. Attention is drawn to the existence of receptor-receptor and receptor-interstitial cell contacts indicating intramural cellular relationships that deserve further study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218948
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