Histochemical observations on the giant neurosecretory cells of the thoracic ganglion of the adult and juvenile crabs, Potamon magnum magnum (Pretzman).

The giant neurosecretory cells in the thoracic ganglion of the adult and juvenile crab, Potamon magnum magnum (Pretzman) were histochemically investigated. The secretion is mainly proteinaceous in nature, containing considerable amounts of acid mucosubstances, sulphate esters, lipids and a little carbohydrate but no glycogen. The detailed nature of proteinaceous neurosecretory material in the adult crab was further tested. It appears that the neurosecretory material of these cells contains moderate amounts of sulfhydryl groups and few of disulphide bonds. No trace of tyrosine could be observed. The neurosecretory granules were associated with considerable amounts of cytoplasmic RNA. In general, stronger reactions were obtained in summer and winter than in other seasons.     

Cytochemical ultrastructural study of the glycoproteins in the rat hypothalamo-post-pituitary complex]

The results obtained with various methods applied to the cytochemical detection of carbohydrates at an ultrastructural level, confirm the existence of glycoproteins in neurosecretory material in the neurohypophysis as well as in the hypothalamic magnocellular nuclei. This glycoproteic component, however, is not present in all the secretory granules and, according to their cytochemical behaviour, it is possible to distinguish two types of neurosecretory fibres: one where all the granules respond negatively; the other where most of the granules are reactive. The existence of two types of neurons corresponding to these two fibres cannot yet be asserted, but seems very likely, perhaps connected with the hormonal duality of the magnocellular nuclei. The reactions are also positive on the Golgi apparatus, in accordance with its function in glycoprotein synthesis. But the difference of reactivity between the Golgi cisternae and the neurosecretory product suggests that glycoprotein synthesis is still going on in the neurosecretory granules outside the Golgi area.     

Presumptive neurosecretion in Leucochloridiomorpha constantiae (Trematoda) and its possible role in governing maturation

A review of literature dealing with neurosecretion in the Platyhelminthes is presented and presumptive neurosecretory cells associated with the cerebral ganglia and longitudinal nerve cords ofLeucochloridiomorpha constantiae metacercariae and adults are described. Both the mean number of aldehyde-fuchsin stained presumptive neurosecretory cells and the intensity of staining are less in adults than in metacercariae. This suggests that maturation in this trematode may be directly or indirectly associated with a reduction in neurosecretion as in nereid annelids. Results of cytochemical studies indicate the neurosecretory product contains a glycoprotein.     

The hypothalamic magnocellular system in the domestic fowl

Summary In the rostral hypothalamus of the domestic fowl, the magnocellular neurosecretory nuclei show a peculiar differentiation. Golgi studies of the supraoptic and paraventricular nuclei of the fowl reveal at least two major cell types: 1) large multipolar neurons, and 2) small interneurons. Golgi impregnations provide a detailed cytoarchitectural picture of the large-sized cells; the latter may well correspond to the neurosecretory cells demonstrated in the same regions by selective staining, and immunocytochemical and electron microscopical techniques.Electron microscopically, neuronal perikarya are observed to contain variable amounts of neurosecretory granules (100–200 nm in diameter; mean diameter of 160 nm) scattered throughout the cytoplasm. The diameters of these granules do not differ statistically in the two principal nuclear areas examined. The perikarya of these neurons display only a few axosomatic synapses containing electron-lucent and dense-cored vesicles (70–90 nm in diameter). Numerous nerve terminals of this type also end on the dendritic ramifications in the surrounding neuropil.     

The neurosecretory system of the eyestalk of Carcinus maenas (Crustacea: Decapoda)

The optic ganglia neurosecretory cells of male and female Carcinus maenas during intermoult are distinguishable into six types based on size, location, appearance and method of secretory material release from the perikaryon. Release occurs via the sinus gland and also, in one case, directly into blood capillaries among the neurosecretory cells themselves. The sinus gland consists of axonal extensions of the neurosecretory cells; no secretory granules are produced there and nuclei observed between the axonal endings are those of ill-defined glial cells.     

Nematosomes or nucleolus-like bodies in hypothalamic neurons,the subfornical organ and adenohypophysial cells of the rat

Summary Fibrillar intracytoplasmic bodies, generally referred to as nematosomes or nucleolar like bodies (NLBs), are not only observed in various types of neurons in the hypothalamus and subfornical organ but also in the glandular cells of the pars tuberalis and the pars intermedia hypophyses. According to their cytochemical properties the NLBs are probably of ribonucleoprotein nature. Within the neurons NLBs occur within perikarya and processes. Their presence within the neurosecretory nerve fibers of the neural lobe proves their ability to migrate within the axon. Morphologic modifications of NLBs are observed in stimulated neurons and after colchicine treatment. Colchicine causes a characteristic dense texture of NLBs and a peripheral agglomeration of mitochondria very similar to the rosette arrangement observed in oocytes. Our findings suggest a structural and functional similarity of NLBs in neurons and oocytes, in which their nucleolar origin appears obvious and where they seem to represent preribosomal material. It is very likely that the axonal migration of the NLBs reflects transport of ribosomal RNA for delayed utilization (as in oocytes).This paper is dedicated to Prof. F. Stutinsky for his 65th birthday.     

Ultrastructural and cytochemical features of SV 40 transformed hypothalamic cell lines

Summary A continuous cell line was previously obtained by Simian Virus (SV) 40 transformation of primary cultures of dissociated mouse fetal hypothalami. One clone from this cell line has been previously shown to possess some of the ultrastructural features, immunological properties and synthesizing capacities of magnocellular hypothalamic neurons which secrete vasopressin and neurophysins. The present paper reports on the morphological characterization of 14 other clones or subclones of the original cell line, using the following criteria: phase contrast microscopy, electron microscopy, Gomori's aldehyde fuchsin staining, cytochemical detection of -glucuronidase, immunochemical staining with antisera against bovine neurophysin I, bovine neurophysin II, lys-vasopressin, oxytocin, LH-RH and TRH.The results allowed the conclusion that the clones as well as the subclones can be distributed into two groups: 1) neurosecretory neurons which all possess several of the ultrastructural and cytochemical features of the neurophysin-vasopressin synthesizing clone, and 2) primitive nerve cells which are devoid of such features but display numerous bundles of filaments. In addition some clones were found to display intermediate features between groups 1 and 2. A similar diversity was observed within clones of the original strain and subclones of a neurosecretory clone. It is suggested that the primitive clones could represent precursors of the neurosecretory clones.This work is dedicated to Professor W. Bargmann in honour of his 70th birthday     

Cytologic characteristics of "dark" and "light" cells in the brain amygdaloid complex

This paper reports data on cytological peculiarities of neurons of two main zones of sexual dimorphism in brain amygdala (dorsomedial nucleus and anterior cortical nucleus). The main attention was paid to some characteristics of "dark" and "pale" cells found in the amygdaloid complex for the first time. It is supposed that the dark and pale cells are targets for gonadal steroids, whose cyclic changes in concentration in the blood difined their functional states. Though the ultrastructure of dark and pale cells of the amygdaloid complex is similar to that of neurosecretory cells of hypothalamus, there are necessary electron microscopic and cytochemical evidences.     

Histochemistry of neurosecretory cells in the cerebral ganglion of the adult or juvenile sweet water crab, Potamon magnum magnum (Pretzman)]

The histochemistry of the neurosecretory material of the PF-positive neurosecretory cells of the cerebral ganglion of the adult and juvenile crab, Potamon magnum magnum (Pretzman) has been investigated. The PF-positive neurosecretory material is proteinaceous and contains considerable amounts of cystine; it is associated with significant amount of cytoplasmic RNA, lipids and phospholipids and with moderate amounts of carbohydrates, though no glycogen could be detected. The significance of these results is discussed.     

Ultrastructure of the protocerebral neurosecretory cells of larval Galleria mellonella, in situ and after culture of the brain in vitro

Three major groups of neurosecretory cells are described in the larval brain of Galleria mellonella at two different times during the last larval instar and in larval brains after 72 hr of culture in vitro. The medial group in vivo consists of four distinct neurosecretory cell types, based on characteristic size and morphology, while the posterior and lateral groups each contain a single distinct type of neurosecretory cell. Morphological differences between the same neurosecretory cells at the different times during the last instar are most apparent in the lateral L-1 cells and in the medial M-2 cells, where pleiomorphism is particularly evident in the size, density and accumulations of neurosecretory granules. The only neurosecretory cells in which apparent synthesis of neurosecretory granules is still observed after culture of the brain in vitro are the medial M-2 cells. The other neurosecretory cell types show no accumulation of neurosecretory granules nor new synthesis of neurosecretory material, but are similar to neurosecretory cells in the brain in vivo in all other respects. The morphology of the neurosecretory cells in the larval brain in vivo and in vitro is discussed in relation to their appearance at the light microscopic level and to a known neurohormonal function of the brain which is maintained during 72 hr in vitro.     

Neurosecretory cells in the optic lobe of two aquatic coleopteran species,Dineutes indicus aube and Cybister rugulosus redt

In each optic lobe and optic peduncle of two aquatic beetles viz. Dineutes indicus and Cybister rugulosus the neurosecretory cells are observed with the help of various histochemical techniques. These cells are arranged to form a discrete group. A group in the optic lobe of both species contains about 25 to 30 neurosecretory cells. On the basis of staining properties the neurosecretory cells are classified into A and B types. These cells stain with chrome haematoxylin-phloxine and paraldehyde fuchsin, but do not stain with azan. Histochemically, the neurosecretory material is positive for proteins and shows a negative reaction for 1,2-glycols. The cells show variations in RNA contents in correlation with the state of secretory activity. Axons of the neurosecretory cell group of the optic lobe are observed directed to the optic peduncle. The axonal tract from neurosecretory cells in the optic peduncle runs towards the lateral margin of the brain.     

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.     

Studies on the neurosecretory system of Ranatra elongata fabricius (Hemiptera: Nepidae) with reference to the distal fate of NCC I and II

With the help of PF and PAVB bulk-stained preparations and sections the neurosecretory system of Ranatra elongata has been described. Two medial, each of 9-10 cells, and two lateral, each of 3-4 cells, groups of neurosecretory cells have been observed in the protocerebrum. Only the A-cells have been found to be positive to PAVB histo- and cyto-chemical technique. Axons of the A-cells after traversing the proto- and deuto-cerebrum emerge from the tritocerebrum as the NCC I. The NCC I after bypassing the corpora cardiaca penetrate the aorta wall. There is no physical continuity between the corpora cardiaca and the NCC I and the two are separable. The NSM from the A-cells, transported by their nerve fibers, has been observed in the aorta wall. On the basis of large accumulation on NSM in the aorta wall the latter has been considered as the storage-and-release organ for the A-material. Corpora cardiaca are found to be devoid of A-material. Axons from the B-cells, after emergence from the tritocerebrum as the NCC II, have been observed to penetrate the corpora cardiaca. On the basis of ample amounts of B-material the glands have been considered as the storage-and-release organ for the B-material only. Observations are compared with results on related species and it is concluded that two independent organ complexes constitute the neurosecretory systemt of R. elongata. The A-cells, their pathways, the NCC I, and the aorta wall comprise the first; and the B-cells, their pathways, the NCC II, and the corpora cardiaca the second. The former is concerned with the elaboration, transportion, storage-and-release of the A-material and the latter with the B-material. Finally arguments are presented to include the aorta wall in the neurosecretory system.     

The development of the corticoliberin- and vasopressinergic elements of the rat hypothalamus during postnatal ontogeny

In 10--81-day and adult Wistar rats, neurosecretory cells were revealed which react with antisera to corticoliberin and vasopressin. Morphometric analysis of these cells in the supraoptic, paraventricular and anterior commissural nuclei shows that in the latter vasopressinergic cells develop somewhat later than in the supraoptic and paraventricular nuclei. Complete differentiation of neurosecretory cells in all the centres investigated is observed in 2-month animals. Studies were also made on the amount of corticoliberin- and vasopressinergic terminals in the external zone of the median eminence. Vasopressin-immunoreactive fibers are more numerous in young rats than in adult ones. Corticoliberin-positive neurosecretory fibers are more abundant in adult animals. Earlier development of vasopressinergic elements corresponds to a hypothesis of a more ancient origin of nonapeptidergic structures as compared to those producing liberins and statins.     

Ultrastructure of the hypothalamic neurosecretory system of the dog

Summary The hypothalamic neurosecretory system of normal dogs was studied by light and electron microscopy after perfusion-fixation. In the supraoptic nucleus most neurons are loaded with elementary neurosecretory granules having a content of low electron density. Neurons with less neurosecretory material and signs of enhanced synthetic activity, as recognized by the changes in the endoplasmic reticulum, were also observed.The vesiculated neurons ofJewell were studied under the electron microscope and various stages of development were described. It was postulated that they originate by a localized process of cytoplasmic cytolysis which ends in the formation of a large aqueous intracellular cavity limited by a plasma membrane. The possible significance of these vesiculated neurones is discussed. Some few myelinated neurosecretory axons are found in the supraoptic nucleus.The neurons of the paraventricular nucleus are smaller and contain less neurosecretory material. This is abundant and very pale in the axons. The median eminence consists of an inner zone, mainly occupied by the neurosecretory axons of the hypothalamic-neurohypophysial tracts, and an outer zone in which some neurosecretory axons end on the capillary of the portal system. This outer zone contains numerous axons with the axoplasm rich in neurofilaments and some containing granulated and non-granulated synaptic vesicles. Some neurons with granulated vesicles were observed in this region. The adrenergic nature of these neurons and axons is postulated.The infundibular process of the neurohypophysis shows small axons with discrete amounts of elementary granules and vesicles of synaptic type at the endings. Some enlarged axons having, in addition, large polymorphic bodies are observed and related to the Herring bodies.The size and morphology of the granules are analyzed along the entire hypothalamic-neurohypophysial system. The changes in diameter and electron density are related to the maturation of the granules and the possible significance of such evolution.Supported by grants from the Consejo Nacional de Investigaciones Cientificas y Técnicas and by the Air Force Office of Scientific Research (AF-AFOSR 963-66).     

Fine structure of the median eminence and the pars nervosa of the bullfrog,Rana catesbeiana

Summary The hypothalamic neurosecretory system of the bullfrog, Rana catesbeiana, was studied with light- and electron microscopy. The median eminence is roughly divided into two portions. The upper portion mostly consists of ependymal cells, glial cells and preoptico-hypophysial nerve tract, whereas in the lower portion, neurosecretory axons, glial cells, processes of glial and ependymal cells, and fine blood vessels of the hypothalamic portal vein are located. A part of the neurosecretory axons of the preoptico-hypophysial tract proceeds to the lower portion of the median eminence. These axons are arranged perpendicularly to the capillaries of the hypothalamic portal vein. The glial cells are densely located in the area of the median eminence where neurosecretory material is abundant. The neurosecretory material in the neurosecretory cells, their axons, the median eminence and the pars nervosa of the bullfrog shows a positive reaction to PAS treatment.The neurohemal area of the median eminence is occupied by many neurosecretory and non-neurosecretory axons, containing neurosecretory granules and/or synaptic vesicles. The axonal portions with the synaptic vesicles which are considered to be the nerve endings abut on the capillaries of the portal system. The size of synaptic vesicles in the axon terminals containing few neurosecretory granules is larger than those in the endings with many neurosecretory granules. Infrequently glial and ependymal processes are interposed between the nerve endings and the capillary wall.In the hilar region of the infundibulum, synapses are frequently observed between the thin fibers with or without neurosecretory granules and dendrites of non-neurosecretory neurons. The probable functions of these synapses are briefly discussed on the basis of our findings. Both in the hilar region of the infundibulum and in the pars nervosa, electron-dense neurosecretory granules of two different sizes were observed. The median eminence contains only one type of granules.The fine structure of the pars nervosa shows similar structures to those of the median eminence. Both in the median eminence and the pars nervosa, the fenestrated endothelium of the capillaries was frequently observed. The thick perivascular connective tissue space containing fibroblasts and collagen fibrils was observed both in the median eminence and the pars nervosa. Vesicles in the cytoplasm of the endothelial cells which appear to take a part in the transendothelial transport were observed.This investigation was supported in part by United States Public Health Service Research Grant, No. A-3678, to Hideshi Kobayashi from the National Institute of Arthritis and Metabolic Diseases and partly by a grant for Fundamental Scientific Research from the Ministry of Education of Japan. The authors wish to express their thanks to Prof. K. Takewaki for his kind encouragement.     

Immuno-enzyme cytochemical demonstration of mesotocinergic nerve fibres in the pars intermedia of the amphibian hypophysis

Summary Immuno-enzyme cytochemical investigations showed that the whole amphibian pars intermedia of the hypophysis is innervated by an intercellular network of peptidergic varicose nerve fibres which contain mesotocin or (and) parts of the mesotocin molecule. The pars intermedia does not contain vasotocinergic fibres. The mesotocinergic fibres are branches of axons leaving the pituitary stalk and the neural lobe. In animals of which the hypothalamic magnocellular neurosecretory preoptic nuclei had been completely removed, the immuno-reactive mesotocinergic fibres of the pars intermedia had totally disappeared. From this result, it is concluded that the mesotocinergic fibres of the pars intermedia of the amphibian hypophysis are axons of neurosecretory perikarya located in the hypothalamic magnocellular neurosecretory preoptic nuclei.Dedicated to Professor Berta Scharrer on the accasion of her 70th birthdayThis investigation was supported by a grant from the Belgian Nationaal Fonds voor Geneeskundig Wetenschappelijk Onderzoek     

Premigratory Changes in the Hypothalamo-Hypophysial Neurosecretory System in the Red-winged Blackbird (Agelaius phoeniceus)*

Abstract

• 1 The hypothalamo-hypophysial neurosecretory system in the Red-winged Blackbird (Agelaius phoeniceus) has been studied with special reference to changes during the period prior to fall migration.
• 2 In September the supraoptic and paraventricular cells were found to be considerably larger with substantial amounts of aldehyde fuchsin positive neurosecretory material (NSM) accumulating in the perikaryon. Large amounts of the NSM were found also in the anterior median eminence and pars nervosa.
• 3 Towards migration time (November), the cells in the hypothalamic nuclei contained very little NSM. A marked decline in the amount of NSM was also seen in the anterior median eminence and probably in the pars nervosa too.
• 4 The release of NSM toward migration time has been discussed as an important event in the sequence of events that control and regulate migratory activity.

     

Immuno-cytochemical demonstration,in the external region of the amphibian median eminence,of separate vasotocinergic and mesotocinergic nerve fibres

Summary By means of single and double immuno-enzyme cytochemical staining techniques, it was shown that the external region of the amphibian median eminence contains separate vasotocinergic and mesotocinergic nerve fibres. Moreover, it was demonstrated that the vasotocinergic fibres also contain neurophysin. In animals in which the hypothalamic magnocellular neurosecretory preoptic nuclei had been completely removed, the immuno-reactive vasotocinergic and mesotocinergic fibres of the median eminence had disappeared. From this result, it is concluded that, at least the great majority of the vasotocinergic and mesotocinergic fibres of the external region of the amphibian median eminence are processes of neurosecretory perikarya located in the hypothalamic magnocellular preoptic nuclei. On the other hand, our results do not exclude the possibility that a minority of these neurosecretory fibres originate from small immuno-reactive perikarya which were found in the tuber cinereum. The observation that both kinds of processes accumulate around blood capillaries of the hypophysial portal system strongly suggests that they play a role in the control of the activity of the pars distalis of the hypophysis.This investigation was supported by a grant from the Belgian Nationaal Fonds voor Geneeskundig Wetenschappelijk Onderzoek     

The hypothalamo-neurohypophysial system in Indian fresh-water goby, Glossogobius giuris (Ham.)

The hypothalamo-neurohypophysial neurosecretory system in Indian fresh-water goby, Glossogobius giuris (Ham.) has been described. The tractus preoptico-hypophyseus serves the function of a morphological and physiological connection between the hypothalamus and pituitary gland. In addition to main mass of the nucleus preopticus cells (cystine/cysteine bearing), a group of few cells in the hypothalamus has also been observed. These cells are situated posterior to the position of the nucleus preopricus and are CH Ph + ve and AF + ve. The neurosecretory material in the cells of nucleus preopticus is in the form of fine granules. The nucleus lateralis tuberis is absent in the fish under study. The disposition of neurosecretory material is heaviest along the fibres of the neurohypophysis in the region of pars intermedia with which it forms a profuse interdigitation. The fibres usually terminate over the blood vessels. The Herring bodies are noticeable at different levels in the neurohypophysis and pars-distalis. Besides the neurosecretory fibres, Herring bodies, non-stainableneurosecretory fibres and blood vessels, the pituicytes are also present in the neurohypophysis (SAKSENA 1974a, b). The intraaxonal flow of neurosecretory material, the vascularization of the nucleus preopticus and hypothalamo-hypophysial regulatory mechanism have been also discussed.