Ultrastructural study on the release of neurosecretory material from the sinus gland of the land crab,Gecarcinus lateralis

Summary Sites of release of neurosecretory material were examined in a neurohemal organ of decapod crustaceans, the sinus gland of the land crab, Gecarcinus lateralis. Such discharge into the circulation seems to occur primarily at interfaces between the neurosecretory axons and the acellular stromal sheath which is interposed between parenchyma and hemolymph. The evidence obtained from electron micrographs of adult specimens indicates that more or less intact secretory granules are released into the extraaxonal space primarily by the process of exocytosis. Synaptic-type vesicles are clustered in parts of neurosecretory axons facing the stromal sheath. Such vesicles are thought to result from rearrangement of membranes temporarily fused at the release site and to a minor degree from fragmentation of neurosecretory vesicles within the axon. The presence of nonmarginal vesicles and the occasional appearance of free intraaxonal dense material are interpreted as indications of a second, probably less frequent, mode of release of neurosecretory material.Supported by grants AM-3984, NB-00840, and NB-05219 from the U.S.P.H.S., administered by Dr. Berta Scharrer.I am greatly indebted to Mrs. Sarah Wurzelmann for her excellent technical assistance. I thank Dr. Dorothy E. Bliss for contributing the animals used in this study, and Mr. Murray Altmann for technical advice.     

The effect of adrenaline and acetylcholine on the hypothalamic-hypophysial neurosecretion in the rat

Summary The present investigation was undertaken to study the effects of adrenaline and acetylcholine on the hypothalamic-hypophysial neurosecretory system in rats.The drugs were injected intraperitoneally and into the lateral brain ventricle. The water diuresis was measured (I group). The animals were killed 45 min after intraperitoneal and 20 min after intraventricular administration of the drugs for the histological observations on the neurosecretory system and the histochemical studies of catecholamines in this area (II group).The antidiuretic effect of adrenaline and acetylcholine was established. The antidiuresis was more remarkable following intraventricular treatment.There was no direct relationship between the amount of neurosecretory substance and ADH activity in the posterior pituitary in the short term experiment after intraperitoneal administration of these drugs.The rapid release of ADH from the posterior pituitary was accompanied with a remarkable output of neurosecretory substance from the neurosecretory cell bodies into the axons and these effects were considerable after intraventricular introduction of the drugs. Some neurosecretory cells in the state of the initial hyperfunction were observed. In the posterior pituitary the initial mobilisation of the neurosecretory material from the neurosecretory terminals following intraventricular introduction of the drugs was observed.The supraoptic nucleus seems to be more sensitive to acetylcholine and the paraventricular nucleus to adrenaline treatment.The significant vasodilatation in the posterior pituitary and in the area of the supraoptic nucleus following intraventricular acetylcholine introduction was established.According to the data described it is possible to expect the existence of control of the hypothalamic neurosecretory activity by means of adrenergic and cholinergic structures.I am very obliged to Prof. W. Bargmann for his stimulating interest in this Study. I am grateful to Dr. G. Leontieva and Dr. V. Govyrin for the possibility to use the fluorescence catecholamine method, to Dr. E. Zeimal and Prof. M. Michelson for using the method for intraventricular injections.     

Histochemical demonstration of monoamine oxidase in the hypothalamo-hypophysial system of the tree sparrow and the rat

Summary Localization of monoamine oxidase (MAO) was investigated essentially according to the method of Glenner et al. (1957) in the hypothalamo-hypophysial system of the tree sparrow and the rat. The hypothalamic neurosecretory cells of both species showed relatively weak MAO activity. A similar localization of MAO activity was observed in the median eminence of both species: (1) slight or no MAO activity was observed in the ependymal layer, (2) relatively strong activity was revealed in the tissue just beneath the ependymal layer, (3) strong activity was revealed in the outer layer, particularly in the tissues surrounding capillary loops of the primary plexus. It is suggested that an adrenergic mechanism functions in the median eminence. In the pars nervosa, strong reaction was observed in the rat, while a weak reaction occurred in the tree sparrow. However, the color and the size of formazan crystals deposited in the rat pars nervosa differed from those in the hypothalamus. As a whole, the distribution of the neurosecretory material differed from the localization of MAO activity in the hypothalamo-hypophysial system. It is discussed that the neurosecretory neuron is not adrenergic but cholinergic.Aided by Grant A-3678 from the United States Public Health Service. The authors are indebted to Dr. S. Kambara, Zoological Institute, and Dr. H. Hirano, Department of Anatomy, University of Tokyo, for their valuable advice, and also to Assoc. Prof. S. Yamamoto, Department of Hygiene, University of Tokyo, for making available some facilities. They also wish to thank Dr. L. M. Barbato, University of Illinois, and Mr. K. Asami, National Institute of Radiological Sciences, Chiba, and Mr. Suzuki, Research Laboratory, Chugai Pharmaceutical Company Ltd., Tokyo, for the kind supply of MAO inhibitors.     

An in situ study of the preoptico-neurohypophysial complex of the freshwater teleost Ciarias batrachus (L.)

Summary The complicated architectural pattern of the preoptico-neurohypophysial neurosecretory system of Clarias batrachus is described using bulk staining procedure. The nucleus preopticus is U-shaped; its limbs constitute the PMC and PPC. The difference in staining intensities noticed among the PMC and PPC might suggest a possible functional difference within the system. Axons of the PMC diagonally pass through the PPC and emerge along with those of the latter to form the right and the left main tracts. The folds and recurrent curves of the neurosecretory axonal tracts, the formation of several pairs of lateral tracts and their union to form median tracts might be devices to increase the storing and releasing capacity for the neurosecretory material. The presence of prominent Herring bodies, and diffuse areas in the neurosecretory tract suggest possible sites of release of neurohormones along the highly vascular hypothalamic region. The common neurosecretory tract is divided into several smaller branches at the level of the pars distalis prior to entering the pars intermedia. Branches do penetrate into the pars distalis, but those entering the rostral component of the pituitary are relatively scarce.Regeneration of the anterior stump of the severed hypophysial stalk to form a neurohypophysis-like organ is also demonstrated in toto with the aid of the bulk staining procedure. A demonstrable increase of stainable neurosecretory material was noticed all along the hypothalamo-neurohypophysial complex of some specimens subjected to complete darkness. Total staining methods could be advantageously used to map the course of recurrent tracts and extra-hypophysial axonal endings. Since the neurosecretory system seems to exhibit a varied structural pattern in different fishes, extension of this study to a larger number of species may throw additional light on the function and the evolution of this important system.I am indebted to Dr. K. N. Udupa, Principal, College of Medical Sciences and Director, Surgical Research Laboratory and Dr. L. M. Singh, Officer in-charge of the Laboratory for providing all facilities and encouragements.     

The structure of the hypothalamic neurosecretory cells of Zoarces viviparus L. under the conditions of constant dark and light during the reproductive cycle

Summary The Structure of the hypothalamic neurosecretory cells during their activity in continuous light and dark conditions and depending on the seasonal alteration has been investigated in Zoarces viviparus L. in the level of light and electron microscopy.The depletion of AF- or AT-stainable material, of the elementary neurosecretory granules and the disappearance of smooth-surfaced vesicles occur during April and June. The accumulation of the stanable material as well as the elementary neurosecretory granules and the smooth-surfaced vesicles has been observed in the cell body in late September.An excess increase in number of the smooth-surfaced vesicles of dark-induced animals and light-induced animals kept in a black stained tank is apparent. On the other hand, the disappearance of the elementary granules and the smooth-surfaced vesicles and an enlargement in the reletive nuclear surface of the neurosecretory cells of light-induced animals which were kept in a gray stained tank in April is also evident.Taking into consideration the responsiveness of both the elementary neurosecretory granules and the smooth-surfaced vesicles in relation to the external environment as well as their topographical arrangement in the cell body the possible differences in their origin and function are discussed.Numerous studies indicate that the physical environment is in part responsible for the functional properties of the hypothalamic neurosecretory centers of various vertebrates. In the level of light microscope, it has been repeatedly shown that the neurosecretory cells are activated in the animals subjected to continuous illumination, and in those subjected to long daily photo period (Oksche et al., 1958; Fiske and Greep, 1959; Öztan and Gorbman, 1960; Satyanesan, 1965). The enlargement of the nuclei and the amount of Gomori — or aldehyde fuchsin — stainable material, as well as the enzymatic activity, were used as the criteria of cellular activity in the histological preparation. In the level of electronmicroscope it has been shown that Gomori positive material (Bargmann, 1949) is represented as aggregated elementary neurosecretory granules in the ultrathin sections of neurohypophysis (Bargmann et al,. 1957). Although the fine structure of the hypothalamic neurosecretory cells of various fishes and higher vertebrates have been studied in normal and experimental conditions (Palay, 1960; Lederis, 1962, 1964; Follenius et Porte, 1962; Follenius, 1963; Murakami, 1961–1964; Gansler, 1965; Holmes, 1965) the type of granules and their function still remains as an open question (see Bargmann, 1963; Knowles, 1965).This work was aided by a grant from Nato and the Deutsche Forschungsgemeinschaft.This paper was written as a tribute in honor of the 60th birthday of Prof. Dr. Berta Scharrer.     

Differences between median eminence and neural lobe in amphibians

Summary The neurohypophysis of the toad Bufo arenarum Hensel can be subdivided into two well defined zones: the median eminence and the neural lobe. In its turn, the median eminence consists of two zones: a neural subependymal one, containing the axons of the hypothalamic-neurohypophysial tract; and a glandular one, made up of the capillaries of the primary plexus of the portal hypophysial system and of neurosecretory axons.Different staining techniques and certain experimental procedures (inanition, dehydration and adenohypophysectomy) showed that there are differences between the neurosecretory material of the neural lobe, which is a place of hormone liberation into the systematic circulation, and the neurosecretory material of the median eminence, which is the site of release of adenohypophysis-stimulating substances into the portal vessels.This work was introduced at the III Sesiones Científicas de Biología, Rosario, Argentina, March, 1965. The study was partially supported by the Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina) and The Rockefeller Foundation (School grant RF-58028).Fellow of the Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina. The author wishes to express his indebtedness to Dr. M. H. Burgos and Dr. F. Sacerdote for their help and criticism, to Miss B. Rodriguez. Miss M. Masot and Mr. L. Castro for their technical assistance.     

Das Neurosekretorische Zwischenhirnsystem der Amsel (Turdus Merula L.) im Jahresablauf und nach Wasserentzug

Zusammenfassung Der Bau des neurosekretorischen Systems der Amsel wurde histologisch untersucht und mit dem anderer Vogelarten verglichen. Dabei wurden an Freilandtieren in einzelnen neurosekretorischen Kerngebieten Aktivitätsschwankungen im Jahresablauf nachgewiesen.Der N. paraventricularis läßt Beziehungen zum Gonadenzyklus erkennen.Der N. magnocellularis interstitialis dorsalis zeigt Korrelationen zu der von Fromme-Bouman gefundenen Nebennierenrinden-Aktivität. Die anderen Kerngebiete weisen keine eindeutigen Beziehungen zum Aktivitätsverlauf der innersekretorischen Drüsen auf. Anzeichen für eine phloxinophile, Gomori-negative Neurosekretion wurden nicht gefunden. Hinterlappen und Eminentia mediana zeigen nur geringfügige und individuelle Schwankungen in der Sekretspeicherung, aus denen sich keine Jahresperiodik ableiten läßt.Nach experimenteller Belastung des Wasserhaushalts treten in allen Kerngebieten — mit verschiedener Häufigkeit — Durstzellen mit stark vergrößerten Kernen auf. Zwei Regionen des Systems mit schwacher Aktivität im Jahresablauf werden durch Wasserentzug besonders aktiviert und enthalten den größten Anteil an Durstzellen: N. lateralis externus hypotahalami (Arai, 1963) und N. entopeduncularis ventralis.Dagegen wurde in zwei weiteren Regionen (N. entopeduncularis anterior und medialis) durch Dehydration eine Inaktivierung der Zellen induziert. Dieses Beispiel zeigt, daß offenbar die Zellen eines funktionell einheitlichen Systems — mit stark wechselndem Anteil — über alle Kerngebiete zerstreut sein können.Es wird die Wahrscheinlichkeit einer Beteiligung der Gomori-positiven Neurosekretion an der Gonadotropin-Ausschüttung diskutiert und die Möglichkeit einer Auslösung von ACTH und TSH durch Substanzen aus dem tubero-hypophysären System besprochen.

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Summary The histology of the neurosecretory system of the Europaen blackbird (Turdus merula L.) is compared with the reports on other species.Parallelism of seasonal activity was found between nucleus paraventricularis and gonadal cycle, nucleus magnocellularis interstitialis dorsalis and adrenal cortical changes. No clear correlation between other neurosecretory regions and endocrines could be detected. No phloxinophile neurosecretion could be found. Median eminence and neural lobe showed small and individual differences, but no annual cycle.After experimental dehydration in all neurosecretory regions strongly hypertrophic cells were observed. Yet their frequency varied greatly.Two regions with low activity during the annual cycle exhibited very strong reaction to dehydration and contained under this condition the highest percentage of hypertrophic cells: nucleus lateralis externus hypothalami (Arai, 1963) and nucleus entopeduncularis ventralis. In two further regions (nucleus entopeduncularis anterior and medialis) dehydration induces inactivation.The results of the dehydration experiments indicate, that the cells of a functional unit might contribute at a varying degree to all regions of the neurosecretory system.

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Herrn Prof. Dr. F. W. Merkel danke ich herzlich für die Anregung zu dieser Arbeit, den Herren Professoren Dr. H. Giersberg und Dr. M. Lindauer für die Gewährung eines Arbeitsplatzes, Herrn Dr. A. Epple für wertvolle Hinweise.     

Hypothalamic neurosecretion and metamorphosis in Xenopus laevis

Summary Tadpoles of Xenopus laevis were treated with propylthiouracil from the second half of prometamorphosis. Sagittal sections of the head region were stained a.o. with pseudoisocyanine. The goitrogen caused a degranulation of neurosecretory cells in the dorsal part of the preoptic region of the hypothalamus, suppressed the development of ventral neurosecretory cells and of the outer zone of the median eminence, stimulated the thyrotropic cells in the adenohypophysis, caused a hypertrophy of the thyroids, and impaired metamorphosis. Returning the animals to tap water had reciprocal effects and restored the normal activity of the hypothalamus, adenohypophysis and thyroid glands. It is concluded that thyroid hormones exert a morphogenetic influence upon hypothalamic centres and the outer zone of the median eminence and that a negative feed back relation exists between the thyroids on the one hand and the dorsal neurosecretory cells and the thyrotropic cells on the other.The author thanks Prof. Dr. P. G. W. J. van Oordt for his active interest and helpful advice, and Miss Tineke Aafjes for technical assistance.     

Ultrastructure of the tube foot wall of a regular echinoid,Diadema antillarum Philippi

Summary An ultrastructural study of the tube foot wall of a regular echinoid,Diadema antillarum, was made. Ciliated microvillous epithelial cells, their inclusions, amoebocytes, and the arrangement of collagen and muscle in the tube feet are described. The neuropile, together with its vesicular components and possible neurosecretory elements, is considered and discussed as are connective tissue bridges across the lumen. Consideration is given to possible functions for the various components of the tube foot.I am indebted to ProfessorN. Millott for his help and encouragement during the course of this work, to Mr.Raynor L. Jones for his expert technical assistance, and to Dr.H. G. Vevers and the Zoological Society of London.     

Hypothalamic neurosecretory activity in relation to the reproductive cycle in the common striped skunk (Mephitis mephitis nigra; order carnivora)

Summary The histological appearance of certain cell groups in the anterior hypothalamus was studied during various phases of the reproductive cycle of the common striped skunk (Mephitis mephitis nigra), a carnivore having a very restricted period of sexual activity. Pronounced changes occur in the amount of stainable neurosecretory material in cells of the supraoptic, paraventricular and anterior hypothalamic nuclei. Material staining with aldehyde fuchsin is stored (or inhibited from being released) in these cells during the sexually quiescent period in both the female and male skunk. The time of approaching sexual activity is characterized by the first signs of release of neurosecretory material from these hypothalamic cells and the peak of estrus and rut coincides with a minimal content of the material.Dedicated to Professor Berta V. Scharrer in honor of her 60th birthday.This study was supported by U.S.P.H.S. Training Grant 5 T 1-GM 102 and Research Grant BN-00840, from the National Institutes of Health. This represents a portion of a dissertation, written under the guidance of the late Professor Ernst Scharrer, and submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Yeshiva University, June, 1965. Preliminary reports of this work were presented at the 78th annual session of the American Association of Anatomists, Miami, Florida, and at the VIIIth International Congress of Anatomists, Wiesbaden, Germany, (Hagedoorn, 1965a, b). I thank Dr. H. W. Deane and Dr. J. Osinchak for their critical reading of this manuscipt.     

Cholinesterases in the hypothalamo-hypophysial neurosecretory system of the White-crowned Sparrow,Zonotrichia leucophrys gambelii

Summary The distribution of cholinesterases in hypothalamo-hypophysial neurosecretory system of the White-crowned Sparrow has been examined histochemically. The perikarya of the neurosecretory cells of the paraventricular and supraoptic nuclei have a high acetylcholinesterase activity. Acetylcholinesterase activity also occurs in the cells of the infundibular nucleus. The proximal parts of the axons of the cells of the neurosecretory and infundibular nuclei have strong acetylcholinesterase activity and weak non-specific cholinesterase activity. In the median eminence, the activity of acetylcholinesterase is strongest in the palisade layer. In the pars nervosa, there is definite, although weak, acetylcholinesterase activity.This investigation was supported by grants from the National Institutes of Health to Professor Farner (B-1353) and to Dr. Kobayashi (A-3678).     

The effect of castration upon the ultrastructure of the rat hypothalamus

Summary The neurosecretory hypothalamic nuclei and the inner zone of the median eminence of castrated rats were studied under the electron microscope. After one month of castration all the neurosecretory neurons of both nuclei show signs of hyperactivity characterized by dilated cisternae of the endoplasmic reticulum containing a macromolecular filamentous material and an increase in the number of ribosomes. After six months of castration, some neurosecretory neurons show an increased number of neurotubules and larger lysosomes than in the controls. Other neurons show a very significant hypertrophy of the endoplasmic reticulum, with large amounts of intracisternal filamentous material. These cells have few neurosecretory granules and in the adjacent synapses the number of granulated vesicles is increased. In the supraoptic nucleus there are two kinds of neurosecretory axons: the clear ones, which are similar to those that appear in control animals and the dark ones, which have smaller elementary granules. In the inner zone of the median eminence the axons show an increase in the number of neurosecretory granules with respect to the controls. After supplementary administration of sexual hormones, all the modifications produced by castration disappear. The ultrastructural changes observed in the neurosecretory nuclei after castration are discussed in relation to those previously described in the neurohypophysis under the same experimental conditions. A feedback regulatory action of sex hormones on hypothalamic neurosecretory neurons is postulated.Supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas and by the Air Force Office of Scientific Research (AF-AFOSR 963-67).We are deeply indebted to Mrs. Defilippi-Novoa and Mr. Alberto Saenz for their skillful assistence.     

Glycogen in the neurohypophysis of toads

Summary Studies with the electron microscope revealed the presence of glycogen granules in the neurohypophysis of toads (Bufo arenarum Hensel). The glycogen appeared as scattered particles or as clusters formed by these particles within the nerve fibers. The scattered granules were intermingled with the neurosecretory granules and with the microvesicles. Chemical assays showed the presence of glycogen in the neurointermediate lobe of the toad's hypophysis.This work was supported by research grants from the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and The Rockefeller Foundation.The authors wish to express their appreciation to Prof. Bernardo A. Houssay and to Dr. Luis F. Leloir for their encouragement during the preparation of this paper; to Miss Susana Camocardi for her technical assistance and to Mr. Luis Millara for the photographic work.     

Light,fluorescence and electron microscopic studies on “neurosecretion” in tritonia diomedia bergh (Mollusca,Nudibranchia)

Summary Membrane-limited electron-dense inclusions designated as elementary neurosecretory granules have a characteristic distribution in cerebropleural ganglia of the nudibranch snail Tritonia diomedia. They occur in the neuropile and also in individual nerve fibres, connectives and commissures. These granules have been found neither in perikarya of nerve cells nor in proximal segments of their processes.Specific fluorescence obtained in Tritonia preparations with Sterba's pseudoisocyanin method for neurosecretory products has the same pattern of location.The distribution of stainable material in preparations prepared with ordinary neurosecretory procedures (chrome haematoxylin-phloxin after Gomori-Bargmann and paraldehydefuchsin after Gomori-Gabe) is similar to that described by different authors in other gastropods, but strongly differs from the locationof elementary neurosecretory granules and of pseudoisocyanin-positive material. The adequacy of different histological methods for studying neurosecretion in gastropods is discussed.     

The effects of adenohypophysectomy on the hypothalamic-hypophysial neurosecretory system and the adrenal gland of the toad Bufo arenarum Hensel

Summary The effects of adenohypophysectomy were studied on the hypothalamichypophysial neurosecretory system and the adrenal glands of Bufo arenarum Hensel. An increase in vascularization of the pars intermedia was found and the neurosecretory material (NSM) in the glandular region of the median eminence disappeared. Its reappearance later was accompanied by hypertrophy of the pars intermedia; differentiated chromophil cells appeared in the pars intermedia around the vessels and, at the same time, the adrenal reverted to normal. These findings are interpreted as hypertrophy and differentiation of the pars intermedia with replacement, at least partly, of the functions of the pars distalis. The probable mechanism of differentiation and the functions of chromophil cells of the pars intermedia are discussed.This paper was presented at the VI Reunión de la Asociación Latinoamericana de Ciencias Fisiológicas (A.L.A.C.F.), Viña del Mar, Chile, 1964. It was carried out under the auspices of the Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina) and the Rockefeller Foundation (School grant RF-58028).Fellow of the Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.The authors wish to thank Prof. M. H. Burgos for his constant interest, Prof. B. A. Houssay, Prof. H. Heller and Dr. J. H. Tramezzani for their criticisms, Miss B. Rodriguez and Mr. L. Castro for their technical assistance.     

Ultrastructure of the plasmodial slime moldPerichaena vermicularis

Summary Mature plasmodia ofPerichaena vermicularis require a light period to induce sporulation. In this paper the ultrastructure and acid phosphatase localization of the mature plasmodium ofPerichaena vermicularis are investigated. Acid phosphatase is localized in vacuoles containing remnants of bacteria and cell organelles. Morphological and histochemical evidence support the interpretation that these vacuoles constitute two types of lysosomes called respectively heterophagic and autophagic vacuoles.Coated vesicles which apparently originate from smooth endoplasmic reticulum are dispersed throughout the plasmodium and frequently associated with lysosomes. Several dumbbellshaped mitochondria are observed in the plasmodium at the onset of fruiting but not during later stages of plasmodiocarp development. Cytoplasmic microtubules are identified inPerichaena vermicularis. Some of these are closely associated with microfilaments.This work was supported by National Science Foundation grants (GB-5884 and GB-8537) to Dr.Ian K.Ross, NSF grant (GB 12371) to Dr.James Cronshaw, and an NSF Traineeship (GZ 445 and 796) to I.Charvat.This constitutes a portion of a thesis presented to the Regents of the University of California by the first author in partial fulfillment of the requirements for the Ph. D. degree.     

The distribution of monoamines in the hypothalamus of the Japanese quail Coturnix coturnix japonica

Summary The distribution of monoamines in the hypothalamus of the Japanese quail (Coturnix coturnix japonica) has been studied using a histochemical fluorescence technique. In the posterior hypothalamus catecholamine-containing nerve fibres are localised in the nucleus tuberis and nucleus hypothalamicus posterior medialis and are linked by fluorescent tracts running in the stratum cellulare internum. Further tracts may be traced from the nucleus tuberis around the base of the third ventricle to the sub-ependymal layer of the median eminence, where they then appear to pass through the hypothalamo-hypophysial neurosecretory tract to terminate in the palisade zone on the portal vascular bed. The innervation of the palisade layer by catecholamines is sparse. The fluorescent terminals are spread evenly throughout both the anterior and posterior divisions of the median eminence. There is no monoamine innervation of the pars nervosa. The paraventricular organ has both 5-hydroxytryptamine- and catecholamine-containing cell bodies and axons may be traced into the region of the nucleus hypothalamicus posterior medialis. In the anterior hypothalamus the neurosecretory paraventricular nucleus contains many catecholamine nerve fibres and terminals. These are linked by fibre tracts to the nucleus basalis and to the nucleus hypothalamicus posterior medialis. The supraoptic nucleus is less well innervated although a dense accumulation of fibres lies in the preoptic recess. The latter is thought to give rise to long axons which pass in association with the neurosecretory tract to end in the nucleus tuberis.Supported by a Grant (AG 24/36) from The Agricultural Research Council. We are indebted to Dr. G. A. Clayton, Institute of Animal Genetics, University of Edinburgh, for supplying the birds.     

Histophysiology of the pituitary gland in correlation with the ovarian cycle in Tor (Barbus) tor (Ham.)

Summary The histophysiology of the pituitary gland has been studied in correlation with the phases of the ovarian cycle in Tor (Barbus) tor. The cyanophilic cells in the proximal pars distalis display changes related to stages in the maturation of the ovary. The cyanophils, which display hypertrophy and hyperplasia and undergo degranulation and vacuolation during maturation, prespawning, and spawning periods, are identified as gonadotrops. Apparently their glycoproteinaceous contents, gonadotropin(s), control the processes of vitellogenesis, ovarian maturation, and initiation of oviposition. Depletion of glycoproteinaceous contents in these cyanophils leads to atresia of oocytes at advanced stages, but it does not appear to interfere with oogonial proliferation. The neurosecretory materials are implicated in female reproduction.I am deeply indebted to Professor H. Swarup for suggesting and supervising this study and to Dr. Grace E. Pickford for her generosity in sending me xerox copies of some articles.     

Electron microscopy of the neurohypophysis in normal and histamine-treated rats

Summary The fine structure of the neurohypophysis has been studied in normal and histamine-treated rats with particular reference to capillary relationships and to the neurosecretory vesicles. Certain new information on the pericapillary space has been developed and is discussed with reference to the existing literature on the posterior hypophysis and other endocrine organs. The membrane-bounded pericapillary space penetrates deeply between surrounding nerve terminals and pituicyte processes, seemingly forming a pervasive metabolic lake which undoubtedly is of physiological significance for metabolic and secretory exchange.Following histamine treatment, the neurosecretory vesicles lose their electrondense centers, the mitochondria in the nerve terminals become swollen, and the capillary endothelium shows evidence of increased pinocytosis. In one rat subjected to painful stimuli, only the first and last of the above alterations are prominent. The experimental results are interpreted in the light of previous work done by other authors, as additional evidence for the identity of the stainable neurosecretion of light microscopy and the neurosecretory vesicles of electron microscopy.The author is greatly indebted to Prof. Dr. med. W. Bargmann for the use of electron microscope facilities and for other invaluable help during the course of the work. To Frau Dr. A. Knoop of the Anatomical Institute in Kiel, and to Frl. Dr. Weichan of Siemens & Halske AG in Berlin, for aid in obtaining the micrographs, a grateful acknowledgement is extended.Presented in part at the 55th meeting of the Anatomische Gesellschaft in Frankfurt/Main, April 9–12, 1958.United States Public Health Service Special Research Fellow, on leave from Department of Anatomy, University of Minnesota Medical School, Minneapolis, Minnesota, USA.     

Fluoreszenzmikroskopische Studien über die Verteilung und Regeneration der Faserglia beiLumbricus terrestris L.

Zusammenfassung Mit einer neuen Orange G-Fluoreszenzmethode (Zimmermann, 1967) können im Zentralnervensystem vonLumbricus terrestris L. sieben verschieden differenzierte Fasergliatypen nachgewiesen werden. Die Verteilung dieser Zellen weist regionale Unterschiede auf. Fortsätze der Faserglia umhüllen korbartig auch die neurosekretorischen Ganglienzellen. Die einzelnen Gliafasern sind aus etwa 50 Å starken Filamenten aufgebaut. Nach unilateraler Läsion des Oberschlundganglions oder Verletzung des Bauchmarks wird das zerstörte Gewebe bis zum 15. Tag nach dem Eingriff in drei Phasen regeneriert. Dabei werden die neurosekretorischen Zellen in einer bestimmten Reihenfolge früher restituiert als die Faserglia. Gleichzeitig ist in den benachbarten intakten Regionen eine Aktivierung der neurosekretorischen Reservezellen zu erkennen. Die neugebildeten Fasergliaelemente gehen aus neurektodermalen Matrixzellen hervor. Dabei werden charakteristische Nervenzell-Fasergliakomplexe ausgebildet. Die funktionelle Bedeutung dieser Befunde wird diskutiert.

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Summary A new Orange G-fluorescence method (Zimmermann, 1967) is applied to the nervous system ofLumbricus terrestris L. for demonstration of fibrous neuroglia cells. The seven different types of these cells reveal a high degree of differentiation and a specific pattern of regional distribution. The processes of the fibrous neuroglia cells form basketlike structures on the surface of neurosecretory cells. The glia fibers are composed of fine filaments (approximately 50 Å thick). After unilateral cauterizing of the supraesophageal ganglion (brain) or lesions put in the ventral nerve cord the damaged tissue is restored within 15 days after the injury (regeneration phases I–III). The regeneration of the neurosecretory system shows a distinct morphological pattern. The replacement of the neurosecretory cells anteceds the restitution of the fibrous neuroglia. In the surrounding intact areas of the nervous system an activation of neurosecretory cells occurs. The matrix of the newly formed glial elements is of ectodermal origin. The development of very obvious complexes formed by neurons and glial satellites was traced by means of fluorescence microscopy. The functional significance of these findings has been discussed.

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Frau Professor Dr.Berta Scharrer gewidmet.

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Teil einer medizinischen Doktorarbeit.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.