Das morphologische, kinetische und endokrinologische Verhalten von hypothalamischem und neurohypophys�rem Gewebe in vitro

Surgical Treatment of Hemangioblastoma in the Pituitary Stalk: An Extremely Rare Case

Hemangioblastoma (HBL) in the pituitary stalk is extremely rare. Only 16 such cases have been reported in the past and 5 cases have been treated with surgical procedure. Here, we report surgical case of HBL in the pituitary stalk diagnosed in a 34-year-old woman. The patient underwent a gross-total resection via the modified lateral supra-orbital approach. No recurrence was observed in two years after surgery. To our knowledge, this is the 17th case of HBL in the pituitary stalk and the 6th surgical case. If the tumor is symptomatic and the volume is over 5 cubic centimeters as in our case, we recommend that the surgical resection of the HBL in the pituitary stalk is a more safe and reasonable than radiotherapy.

Structure and function in the conceptual development of mammalian neuroendocrinology between 1920 and 1965

With the growing realization in the 1930s that the brain played a crucial role in regulating the secretions of the pituitary gland, neuroendocrinology as we now know it developed from two rather separate directions. One approach relied heavily on morphological techniques to define neurosecretion; a novel, but for many years flawed model that was originally developed to explain the presence of gland-like cells in the diencephalon. During its first 20 years neurosecretion, as a concept, made no significant contribution to our understanding of how the pituitary was controlled. Then, following the identification by Sanford Palay and Wolfgang Bargmann of a continuous neurosecretory pathway from the hypothalamus to the neural lobe, neurosecretion became incorporated into a more broadly based concept of pituitary function, particularly regarding the neural lobe. The second approach integrated structural and functional methods to investigate neural regulation of the pituitary. This work eventually explained how the pituitary was controlled by the brain. It led directly to our understanding of the control of vasopressin and oxytocin release by neuroendocrine terminals in the neural lobe, the neurohumoral control of the pars distalis, and eventually to a detailed description of the neural networks that control pituitary function. As increasingly sophisticated morphological, neurophysiological, and eventually molecular biological techniques were applied to the problem, the original notion of the diencephalic gland and neurosecretion became unsustainable. The gland-nerve cells of the 1930s became the neurosecretory cells of the 1940s and 1950s, and then finally neuroendocrine neurons in the 1960s. From then on neuroendocrinology developed into the more unified discipline we know today. The chronology of these two approaches will be examined here using examples from research that occurred approximately between 1920 and 1965. The goal is not to give a comprehensive history of pituitary function or neuroendocrinology. Instead, the focus will be to compare the rationales and effectiveness of two contrasting experimental approaches: predominantly structural analyses as opposed to more integrated approaches.

Presynaptic fibres of spiral neurons and reciprocal synapses in the organ of Corti in culture

Isolated segments of the newborn mouse organ of Corti were explanted together with the spiral ganglion components. Within the innervation provided by the spiral neurons, we observed presynaptic vesiculated nerve endings that form reciprocal ribbon-afferent/efferent synapses with inner hair cells. These intracochlear presynaptic fibres are characteristically located between adjoining inner hair cells, on the modiolar side, low and close to the supporting cells. The presynaptic fibres display different modes of synaptic connectivity, forming repetitive reciprocal synapses on single inner hair cells or on adjoining hair cells, or connecting adjoining inner hair cells through simultaneous efferent synapses. Many presynaptic fibres exhibit a distinctive ultrastructure: defined clusters of synaptic vesicles, dense core vesicles, coated vesicles, and mitochondria. These organelles occur focally at the synaptic sites; beyond the efferent synaptic specializations, the endings appear quite nondescript and afferent-like. We believe that the reciprocal synapses, although observed in cultures of the organ of Corti, represent real intracochlear synaptic arrangements providing a feedback mechanism between the primary sensory receptors and a special class of spiral ganglion cells that have yet to be recognized in the organ in situ.

Demonstration of glial fibrillary acidic (GFA) protein by electron immunocytochemistry in the granular cells of a choristoma of the neurohypophysis

The origin of the nests of granular cells comprising choristomas of the infundibular process and the stalk of the pituitary gland is controversial. Using electron microscopic immunocytochemistry, the astrocytic marker, glial fibrillary acid protein (GFAP), has been demonstrated diffusely in the cytoplasm of some of the granular cells, but not within the granules or cellular organelles of some of the granular cells. Cytoplasmic filaments were not detected in these granular cells, but cells with abundant filaments extended processes between the granular cells. These filament-rich cells stained much more intensely for GFAP than the positively staining granular cells. The expression of GFAP by the granular cells and the filament-containing cells between them in the pituitary implies an astrocytic origin for both cell types, but the absence of filaments in the granular cells suggests that the GFAP is in an unpolymerized (soluble) form. The granular cell is likely to represent a transitional cell type of astrocytic origin in which the glial filaments have undergone partial or complete degradation.

Long-term suspension culture of isolated hypothalamic nuclei of the rat: morphological differentiation and release of substances influencing corticotropin and growth hormone secretion

Individual hypothalamic nuclei were removed from 17-day-old rat embryos with 300 microns punches and maintained in suspension culture. Suspension culture of isolated nuclei appears to be suitable for studying morphological and functional differentiation of neural tissue and release of bioactivity influencing corticotropin and growth hormone release. During the 4 weeks in culture, neurons and glial cells differentiated well in each nucleus studied. The fine structure of the arcuate, periventricular, ventromedial and dorsomedial nuclei resembled that of the adult nuclei with many mature synapses; in contrast, in the neuropil of cultured preoptic, paraventricular and posterior hypothalamic nuclei mature synapses were very few or absent. The release of substances influencing corticotropin and growth hormone secretion by the cultured nuclei was tested in bioassays using anterior pituitary cell cultures and radioimmunoassay of hormones released into the medium. Corticotropin-releasing bioactivity was tested at weekly intervals. Cultured preoptic and paraventricular nuclei released corticotropin-releasing activity for up to 4 weeks whereas arcuate nuclei released corticotropin-releasing activity at 1 week only. The ventromedial and dorsomedial nuclei did not release corticotropin-releasing activity. The release of substances influencing growth hormone secretion was studied between 3 and 11 days in culture. After 3 days the medium of some hypothalamic nuclei stimulated growth hormone secretion, but after 7 and 11 days all cultured nuclei strongly inhibited it. The present findings demonstrate that hypothalamic nuclei can be cultured separately and suggest that neurons capable of releasing corticotropin-releasing activity(ies) are present in the preoptic and paraventricular nuclei of the rat whereas all hypothalamic nuclei studied contain intrinsic neurons capable of synthesizing and secreting somatostatin-like bioactivity.

Detection of bovine pancreatic trypsin inhibitor (bPTI) in bovine and ovine pituitaries, bovine brain, and adrenal medulla. A specific radioimmunoassay for bPTI

An antiserum against bovine pancreatic trypsin inhibitor (bPTI) has been raised in rabbits. The antiserum does not cross-react with known pituitary hormones and other proteins. A specific radioimmunoassay for bPTI has been developed. The ED50 is about 250 fmol per assay tube and the sensitivity is reliable to 15 fmol per tube. Immunoreactivity could be detected in bovine and sheep pituitaries, bovine brain, and adrenal medulla, but not in human, pig, and rat pituitaries. In the bovine pituitary the immunoreactivity is restricted to the posterior lobe.

Single neuron cultivation of embryonic and perinatal rabbit or rat brains based on plasma clot technique

Isolated neuronal cells dissociated from the brain of embryonic rabbits on the sixteenth day of gestation and of perinatal rats (eighteenth embryonic day, to E18, thirteenth day postnatum, p.n. 13) were selectively cultured using a plasma clot technique. The cells grown were shown to be neurons by means of the neuron-specific synaptosomal plasma membrane antibody (SPM). They differentiated at a very high frequency from rounded cells lacking processes into different shapes characteristic for several neuronal cell types. Morphological differences could be distinguished even after 24 h in culture. The neurons differentiated in vitro for up to 11 days, apparently without need of any direct intercellular contact. Cells caught inside the plasma clot were prevented from decreasing in number. This provides the opportunity to culture few neurons even from an extremely small area of a single brain. As an example, different cell types are shown originating from rat cerebella aged E18 to p.n. 13. Their appearance apparently corresponds to the genesis of cerebellar cell types, as is known from the in vivo situation. The high degree of characteristic neuronal differentiation and the prevention of direct intercellular contacts indicate that this culture method may serve as an in vitro assay for genetically fixed properties acquired in vivo.

Cultured neurones from the mature bovine mediobasal hypothalamus contain LHRH but not catecholamine

The in vitro culture of mature neurones from bovine mediobasal hypothalamus (MBH) is reported, providing a model for studies of mammalian neurosecretion at the cellular level. Explant tissue cultures of mature bovine MBH containing the arcuate nucleus were examined for LHRH, ACTH and catecholamines with a view to investigating the control of prolactin and gonadotropin secretion. LHRH immunoreactivity was found in both neuronal and non-neuronal cells in the outgrowth monolayer region of the explant. Neurones in this region appeared able to attach to a substrate and regenerate, in monolayer culture, well developed neurites characterized by beaded swellings as observed in vivo. Neither ACTH immunoreactivity nor catecholamine fluorescence was detected. Cultured neurones and astrocytes were labelled by tetanus toxin and anti-GFAP, respectively. Double labelling of cultures with tetanus toxin and anti-LHRH demonstrated the neuronal nature of many LHRH-immunoreactive cells. Radio-immunoassay data confirmed the presence of LHRH in the cultures but application of 60 mM KC1 failed to evoke hormone release. These studies have confirmed the view of previous workers that hypothalamic control of prolactin secretion in the bovine may be very different from that thought to occur in non-ruminants such as the rat and guinea pig. Finally, this work demonstrates that a cultured system from the mature bovine may prove a good model for study of neuronal regulation of gonadotropin secretion by the bovine mediobasal hypothalamus.

Morphologic features of the caudal neurosecretory system in the blueback herring, Pomolobus aestivalis

The caudal neurosecretory system of the blueback herring, Pomolobus aestivalis, captured in freshwater, was examined. Neurosecretory cells were identified readily in terminal spinal cord segments. The axonal processes of these neurosecretory cells formed a discrete, ventrally placed bundle which terminated in a conspicuous ventral enlargement from the filum terminale. This enlargement comprises the neurohaemal contact zone or urophysis. The neurosecretory terminals were engorged with secretory granules in these fishes from a freshwater environment. The non-neuronal component of the urophysis also was examined in this study. These glial cells were dispersed throughout the urophysis. Most often they were found ensheathing the terminal neurosecretory processes. These cells showed a resemblance to neurohypophysial pituicytes. Although mentioned in the literature, these glial cells have not been examined with the electron microscope. The ultrastructural features of the glial cells and their relation to the neurosecretory constituents are described in this report.

Neurones with synchronous bursting discharges in organ cultures of the hypothalamic supraoptic nucleus area

Explants of the hypothalamic supraoptic nucleus area from newborn rats were cultured. Ultrastructural studies revealed the existence of typical neurosecretory granules in neuronal perikarya as well as in axons. Large nerve cells that were spontaneously active discharged at an average firing rate of 7.2 +/- 4.4 (S.D., n = 98) spikes/sec and 42% of these neurones displayed a phasic firing pattern as shown by the existence of peaks in their autocorrelograms. The firing of 59% of the neurones was synchronous with the activity of other nerve cells. In some neurones, only the onsets of bursts were correlated, whereas in others periods of high correlation alternated with periods of no correlation. The relative proportion of rhythmically or synchronously firing hypothalamic neurones was not altered when a neurohypophysial explant was co-cultured. Field stimulation in the cultures resulted in a short-latency excitation followed by an inhibition which was found to be bicuculline-sensitive. The existence of functional synapses was furthermore demonstrated by intracellular recordings of postsynaptic potentials.

Rate of movement and redistribution of stainable neurosecretory granules in hypothalamic neurons

Electrical stimulation of the olfactory tract of goldfish for one minute can deplete completely the stainable neurosecretory granules from cells of the preoptic nucleus as well as from their axons. Thus, in stimulated neurons secretory granules appear to move toward the neurohemal point of discharge at a rate of about 2 millimeters per minuite. Reaccumutlation of neurosecretory granules in depleted neurons to approximately normal numbers requires about 1 to 1.5 hours. Histological evidence indicates that, during the period of reaccumulation, granules move out of the perikaryon until normal granulation in the axons is achieved; finally, granulation of the perikaryon is restored.