Brain tissue transplanted to the anterior chamber of the eye

Summary Small pieces of fetal rat brain selected to contain a high number of noradrenaline (NA), dopamine (DA), or 5-hydroxytryptamine (5-HT) neuroblasts were transplanted to the anterior chamber of the eye of adult rats. The sympathetic ground plexus of the host iris was removed by superior cervical ganglionectomy so that transmitter mechanisms of the different central monoamine fibers innervating the iris could be selectively studied after intraocular maturation. Such irides, containing NA, DA, or 5-HT nerve terminals were incubated with radiolabelled transmitters and then stimulated by an electrical field while superfused, to investigate the spontaneous and stimulation-induced release of amine, both in drug-free buffer and buffer containing drugs acting on monoamine receptors.The central monoamine neurons of all three types were able to take up exogenous amines and release them upon stimulation by an electrical field, in much the same way as corresponding nerves in situ in slices of cerebral cortex (NA, 5-HT) or olfactory tubercle (DA).The -adrenergic receptor blocking agent phentolamine increased the stimulation-induced release of ³H-NA from central NA fibers on the iris significantly. The dopamine receptor stimulating agent apomorphine decreased the stimulation-induced release of ³H-DA from central DA fibers on the iris. Pimozide, a DA receptor blocking drug tended to increase the ³H-DA release. The 5-HT receptor stimulating agent ergocornine tended to reduce the stimulation-induced release of ³H-5-HT from central 5-HT fibers on the iris. It was concluded that all three types of central monoamine nerve fibers develop essentially normal transmitter storage and release mechanisms also in an environment completely devoid of normal postsynaptic receptors. The drug experiments add strong support to the view that there are presynaptic monoamine receptors (autoreceptors) able to modulate transmitter release present on the monoamine nerve terminals.Supported by the Swedish Medical Research Council (04X-3185 and 04X-2330) and by grants from Magnus Bergvalls Stiftelse and Karolinska Institutets Fonder, we thank Miss Ingrid Strömberg and Miss Ulla Enberg for skilful technical assistance.     

Histochemical studies on the distribution of catecholamines and 5-hydroxytryptamine after intraventricular injections

Summary Using the histochemical method for the demonstration of DA, NA and 5-HT it has been possible to demonstrate, in reserpine treated rats, that intraventricularly administered DA, NA, -methyl-DA and -methyl-NA in doses of 1–2 g are specifically taken up by the parts of the DA and NA neurons lying close to the ventricles and the subarachnoidal space. The distribution of this uptake is described in detail. No uptake and accumulation of DA and NA was observed unless the monoamineoxidase had been inhibited whereas the -methylated compounds which are resistant to monoamineoxidase accumulated without monoamineoxidase inhibition. Intraventricularly administered 5-HT was specifically taken up and accumulated in the 5-HT neurons within the same zone provided that monoamineoxidase had been inhibited. The distribution of this uptake is described in detail. After high doses of CA (5–10 g) these amines accumulated to some extent also in the 5-HT neurons while no such accumulation was observed in the CA neurons after high doses of 5-HT. Thus, the present results indicate that there exists a specific reserpine-resistant, amine-concentrating mechanism at the nerve cell membrane of CA and 5-HT neurons. In areas where the exogenous amine concentrations probably were high there also occurred an accumulation of DA and NA in the CA neurons although the monoamineoxidase was not inhibited. Finally, in a certain area of the hypothalamus, CA was found to accumulate even after low doses (1–2 g), in nerve cell bodies which probably normally do not contain CA.This study was supported by a research grant from the Swedish Medical Research Council (12x-715-03) and by grants from M. Bergwalls stiftelse and C. Nathorsts stiftelse.     

Influence of chronic inorganic lead exposure on regional dopamine and 5-hydroxytryptamine turnover in rat brain

The results of previous behavioral studies utilizing chronic exposure to low amounts of inorganic lead (Pb) have suggested alterations in the function of biogenic amine neuronal systems. The following study was performed to provide evidence for the possible bases of these changes in pharmacological responsiveness in exposed animals. Dams were administered 0.2% Pb acetate in drinking water to expose their offspring to Pb via the maternal milk. Males were weaned to the same drinking solution. At 120–140 days a tracer dose of 1.0 mCil-[³H]2,6-tyrosine (³H-TYR) and 0.5 mCil-[³H(G)]tryptophan (³H-TRP) was injected through an indwelling jugular catheter, and norepinephrine (NE), dopamine (DA), 5-hydroxytryptamine (5-HT) and their respective precursors and metabolites were quantified by liquid chromatography with electrochemical detection with column eluate collected for liquid scintillation counting. At this level of exposure (blood lead (PbB) at day 90 in exposed animals=43.1±1.7 g/dl) no changes were observed in concentration Nf NE or DA mr DA metabolites in any brain region. However, DA turnover was decreased in Pb-exposed animals in nucleus accumbens and frontal cortex. No changes in 5-HT content and turnover were observed in any brain region, but 5-hydroxyindoleacetic acid (5-HIAA) levels were decreased in 6 of the 9 brain regions examined. These findings are consistent with observations of an attenuated behavioral responsiveness to d-amphetamine (AMPH) in exposed animals, and suggest that the changes in DA and 5-HT neurons noted by other workers at higher levels of exposure persist when PbBs are in the range of 40 g/dl.     

Amphetamine Increases Extracellular Concentrations of Glutamate in the Prefrontal Cortex of the Awake Rat: A Microdialysis Study

Using microdialysis, the effect was investigated of intracerebral infusions of different doses of amphetamine (1.25, 2.5, 5, 10, and 20 g/l) on the extracellular concentrations of glutamate in the medial prefrontal cortex of the rat. Amphetamine produced a dose-related increase in extracellular concentrations of glutamate. At the highest dose, amphetamine increased extracellular glutamate by 445% of baseline as well as extracellular concentrations of taurine, and reduced extracellular concentrations of glutamine. Amphetamine did not modify other amino acids such as arginine. Increases in extracellular concentrations of glutamate and taurine were independent of calcium in the perfusion medium. This is the first study showing that amphetamine produces a calcium-independent increase in extracellular concentrations of glutamate and taurine in the medial prefrontal cortex of the rat.     

Effects of α2- and β-adrenoceptor agonists on growth hormone secretion following lesion of the noradrenergic system of the rat

The aim of the present investigation was to lesion the noradrenergic system and to measure the effect on growth hormone (GH) secretion following peripheral administration of ₂- and -adrenoceptor agonists. Direct injection of these agonists into the paraventricular nucleus of the hypothalamus (PVN) and its effect on GH secretion were also investigated. Systemic administration of N-2-chloroethyl-N-ethyl-2-bromobenzylamine (DSP₄, 60 mg/kg, injected i.p. 10 days prior to experimentation) significantly decreased the noradrenaline (NA) content of the hippocampus, frontal cortex and hypothalamus but had no effect on the dopamine (DA) or serotonin (5-HT) content of these areas. Bilateral injection of 6-hydroxydopamine (6-OHDA, 10 g/l, 14 days prior to experimentation) into the medial forebrain bundle (MFB) caused a greater reduction of NA and also decreased the DA and 5-HT content of the hypothalamus. Analysis of the PVN of the hypothalami of rats following 6-OHDA lesion of the MFB showed significantly decreased NA and 5-HT content. Neither DSP₄ treatment nor 6-OHDA lesion of the MFB affected the clonidine (250 g/kg, i.p.) induced stimulation of GH secretion. Injection of isoproterenol (1 mg/kg, i.p.) had varying effects on GH secretion. It stimulated GH release in control rats but not in DSP₄ or MFB lesioned rats. Direct injection of clonidine (0.1 g/l) into the PVN significantly stimulated GH secretion, whereas injection of isoproterenol (2.5 g/l) into the PVN did not affect GH levels when compared to controls. The results of the present study do not support the hypothesis that hypoactivity of the central noradrenergic system may be the cause of the blunted GH response to clonidine observed in depressed patients.     

Presynaptic Modulation of K+-Evoked [3H]Dopamine Release in Striatal and Frontal Cortical Synaptosomes of Normotensive and Spontaneous-Hypertensive Rats

Regional differences in presynaptic [³H]dopamine ([³H]DA) release and its modulation by D₂ DA-receptors between the frontal cortex and striatum obtained from Wystar-Kyoto (WKY) and spontaneous-hypertensive rats (SHR) have been evaluated using superfused synaptosomes. Synaptosomal tritium content was significantly lower in the frontal cortex than in the striatum in both SHR and WKY (45% and 48%, respectively), but no differences in tritium content were obtained between strains. However, the 15 mM K⁺-evoked [³H]DA overflow was lower in the SHR as compared to WKY rats in both brain regions (striatum 23%, frontal cortex 21). Concentration-response curves for quinpirole (1nM-10 M)-mediated inhibition of 15mM K⁺-evoked [³H]DA release showed no differences between SHR and WKY. These results suggest that SHR has less ability to release [³H]DA as compared to WKY rats, but SHR did not show differences in the autoregulation of such release in both the frontal cortex and striatum.     

Effects of an Analog of Vasopressin on the Content of Biogenic Amines in the Brain Structures and Blood of Rats in Alcohol Intoxication

On rats with genetically determined inclination to ethanol consumption under conditions of free choice between ethanol solution and water as liquids for drinking, we studied the effects of an analog of vasopressin (anVP, the tetrapeptide corresponding to the ring part of the molecule of this hormone) on the contents of noradrenaline (NA) and serotonin (5-HT) in the hypothalamus, midbrain, and neocortex and also on the contents of adrenaline (A), NA, and 5-HT in the blood. Injections of 1.0 g/kg anVP did not significantly change the above indices. Injections of this agent in a higher dose (5.0 g/kg) resulted in an increase in the content of NA in the hypothalamus by 80%, on average, and in a decrease in the A level in the blood by 40%. At the same time, the level of 5-HT in all the brain structures under study dropped rather sharply. After injection of 5.0 g/kg anVP against the background of acute alcohol intoxication (infusion of 4.0 g/kg ethanol into the stomach), the level of biogenic amines, which to a considerable extent changed under conditions of such intoxication, demonstrated clear trends toward normalization in all the studied brain structures.     

Dynamic response of a circadian pacemaker

The Culex circadian pacemaker's response to phase-resetting light signals was studied in the first 3 cycles of darkness following a 12h light exposure. (1) In both cycles 1 and 2 there is a clear change from type 1 to type 0 phase-resetting as the resetting signal is prologed (Fig. 2). (2) Mosquitoes in cycle 1 are about half as sensitive to phase-resetting as those in cycles 2 or 3 (the criterion being the minimum pulse duration required to produce type 0 phase-resetting) (Fig. 2). (3) Each cycle appears to have a corkscrew-shaped phaseresetting surface and a phase singularity (Figs. 4, 5, and 7). The hypothesis that the Culex pacemaker reaches a stable limit cycle within the first cycle leads to an economical explanation of the results.     

Studies on uptake of intraventricularly administered tritiated noradrenaline and 5-hydroxytryptamine with combined fluorescence histochemical and autoradiographic techniques

Summary Tritiated noradrenaline (NA) and 5-hydroxytryptamine (5-HT) (1.5–30 C) have been injected intraventricularly into normal or reserpine-nialamide pretreated rats 1/2 to 2 hours before the killing. Various parts of the brains were freeze-dried, reacted with formaldehyde gas and embedded in paraffin or Araldite. Before application of the stripping film emulsion many sections were photographed in the fluorescence microscope in order to perform a combined histochemical and autoradiographic study of the monoamine neurons. By such an approach it was possible to demonstrate 1. that the accumulation of radioactivity in cell bodies after ³H-NA and ³H-5-HT injection is localized to catecholamine (CA) and 5-HT cell bodies respectively; 2. that injected ³H-NA and ³H-5-HT in the doses used relatively selectively are taken up into the NA and 5-HT nerve terminals respectively, since the distribution of grains in the sections follow that of the fluorescent terminals; 3. that the accumulation of silver grains only reaches the zone (200–400 ) close to the ventricles and the ventral part of the subarachnoidal space. By grain counting it was possible to estimate that the degree of concentration of radioactivity in the monoamine cell bodies was up to 4 times that in the immediate surroundings. — The Araldite sections consistently gave a better resolution in the autoradiographic picture than the paraffin sections. It is postulated that freeze-drying and plastic embedding for autoradiography will be a valuable method for the cellular demonstration of certain biogenic amines which are not easily demonstrated by the histochemical fluorescence method and of other biologically active water-soluble compounds, since diffusion will be restricted to a minimum.This work has been supported by grants from the Medical Research Council (14X-715-04A, B69-14X-530-04) and by grants from M. Bergvalls Stiftelse and E. och O. Ericssons Stiftelse.     

Neither a mentalist nor a reductionist be!

There is basis for concern that applied psychophysiology, if not the field of biofeedback, is being coopted by, and merged into, a reborn inner model, with the return of cognition to preeminence in the psych and neuro disciplines. Despite currently fashionable views that such mentalistic inventions and neuro/psychological developments somehow illuminate behavior or offer simpler accounts of behavioral facts, there is little or no evidence that any such construction has ever told us anything new about behavior.Preparation of this article was supported in part by the following PHHS Grants: NHLBI HL 34034, NIDA DA 03476, NIDA DA 04130, NIDA DA 02490, NIDA DA 04133, NIDA DA 01147, NIDA DA 04731, and NIDA contract 271-86-8113.     

Foot-shock stress enhances the increase of [35S]TBPS binding in the rat cerebral cortex and the convulsions induced by isoniazid

We report earlier that isoniazid and foot-shock stress individually increase the maximal number of [³⁵S]TBPS binding sites (B_max) measured ex vivo in unwashed membranes from rat cerebral cortex and that the increase due to both treatments are prevented by pretreatment in vivo with diazepam which alone induced a significant decrease in the total number of [³⁵S]TBPS binding sites. In the present paper, the effect of stress was studied on both the increase in [³⁵S]TBPS binding and the convulsant activity induced by isoniazid in unstressed rats. Isoniazid induced a time dependent increase in [³⁵S]TBPS binding. The isoniazid-induced increase in [³⁵S]TBPS binding was markedly potentiated by foot-shock stress. Moreover, foot-shock stress markedly reduced the latency to the appearance of generalized seizures induced by isoniazid (300 mg/kg s.c.). The results provide evidence that the in vivo inhibition of GABAergic transmission elicited by isoniazid results in an increase of [³⁵S]TBPS binding in the rats cerebral cortex. The finding that stress, like isoniazid, enhances [³⁵S]TBPS binding suggests that this treatment also inhibits the function of GABAergic synapses.     

Structure and function of H+-ATPase

(1) Extensive studies on proton-translocating ATPase (H⁺-ATPase) revealed that H⁺-ATPase is an energy transforming device universally distributed in membranes of almost all kinds of cells. (2) Crystallization of the catalytic portion (F₁) of H⁺-ATPase showed that F₁ is a hexagonal molecule with a central hole. The diameter of F₁ is about 90 Å and its molecular weight is about 380,000. (3) Use of thermophilic F₁ permits the complete reconstitution of F₁ from its five subunits (, , , , and ) and demonstration of the gate function of the -complex, the catalytic function of (supported by and ), and the H⁺-translocating functions of all five subunits. (4) Studies using purified thermostable F₀ showed that F₀ is an H⁺-channel portion of H⁺-ATPase. The direct measurement of H⁺-flux through F₀, sequencing of DCCD-binding protein, and isolation of F₁-binding protein are described. (5) The subunit stoichiometry of F₁ may be ₃₃. (6) Reconstitution of stable H⁺-ATPase-liposomes revealed that ATP is directly synthesized by the flow of H⁺ driven by an electrochemical potential gradient and that H⁺ is translocated by ATP hydrolysis. This rules out functions for all the hypothetical components that do not belong to H⁺-ATPase in H⁺-driven ATP synthesis. The roles of conformation change and other phenomena in ATP synthesis are also discussed.     

Differential staining of catecholamines, 5-hydroxytryptamine and related compounds in aldehyde-fixed tissues

Summary Factors influencing the fixation of biogenic amines by solutions of glutaraldehyde, formaldehyde, acrolein and glyoxal as well as the influences of these aldehydes on the histochemical reactivity of biogenic amines, have been extensively investigated. Selective stainings of 5-hydroxytryptamine, noradrenaline, dopamine and related substances in many aldehyde-fixed tissues have been achieved by systematically applying some phenol methods such as argentaffin, ferric-ferricyanide, diazonium and thioindoxyl reactions, and some indole methods such as xanthydrol, dimethylaminobenzaldehyde, vanilline, salicilaldehyde and benzaldehyde tests.The list of the structures which react like 5-hydroxytryptamine in in vitro tests includes enterochromaffin cells, carcinoid tumours, rodent mast cells, thyroid C cells, a kind of cell found in the human carotid body and chemodectomas, and some cells secreting protein hormones. NA cells of the adrenal medulla, another kind of cell in the carotid body and chemodectomas, as well as ruminants' mast cells, reacted like catecholamines in in vitro tests.Supported by grant No. 115.1139.04715 from the Italian Consiglio Nazionale delle Ricerche.     

Contextualizing Images in Dreams and Daydreams

A contextualizing image (CI) is a powerful central image of a dream which appears to contextualize (provide a picture-context for) the dreamer's emotion. For instance, dreamers who have experienced any serious traumatic event sometimes dream, I was overwhelmed by a tidal wave. This appears to picture their feeling of terror and/or vulnerability.A scoring system for CIs is examined here and is applied to dreams and daydreams supplied by 40 students. Two raters scoring dreams on a blind basis showed good inter-rater reliability. Recent dreams were shown to have more as well as more intense CIs than recent daydreams; likewise, dreams that stand out had more intense CIs than daydreams that stand out. Students with thin boundaries had more and more intense CIs than students with thick boundaries in their recent dreams and nightmare, but not so clearly in dreams and nightmares that stand out. The emotions judged as contextualized by the powerful images tended towards fear/terror and helplessness/vulnerability in dreams (especially in dreams that stand out) whereas emotions contextualized by images in daydreams showed a wide range with no clusters.     

Stimulation of ethylene production by catecholamines and phenylethylamine in potato cell suspension cultures

The catecholamines (50 M dopamine, 50 M norepinephrine and 100 M epinephrine) and phenylethylamine (200 M) were found to stimulate ethylene production in potato suspension cultures. When 100 M amino-oxyacetic acid was added together with epinephrine, ethylene release returned to control levels. The endogenous 1-aminocyclopropane-1-carboxylic acid levels were increased in parallel with the release of ethylene, suggesting that the observed effect probably occurs via regulation of aCC synthase. Our results suggest that there is a link between these naturally occurring monoamines and ethylene in plants.Abbreviations AOA amino-oxyacetic acid - ACC 1-aminocyclopropane-1-carboxylic acid - DA dopamine - NE norepinephrine - E epinephrine - CA catecholamines - PEA phenylethylamine     

Local Perfusion of Nicotine Differentially Modulates Somatodendritic Dopamine Release in the Rat Ventral Tegmental Area After Nicotine Preexposure

We examined the effects of nicotine perfusion into the ventral tegmental area (VTA) on extracellular dopamine (DA) levels in rats using in vivo microdialysis. Local perfusion with nicotine for 80 min (10–100 M) modestly increased (105–131% of basal) the extracellular DA levels in the VTA of rats that had been pretreated with saline for 5 days. In animals that had been pretreated with nicotine for 5 days (0.3 mg/kg, s.c.), perfusion with nicotine for 80 min (10–100 M) dose-dependently increased the extracellular DA levels in the VTA of rats and did so to a greater extent than in saline-pretreated animals (125–171% of basal). Co-perfusion through the dialysis probe with 100 M mecamylamine, a nonselective nicotinic acetylcholine receptor (nAChR) antagonist, or 100 M dihydro--erythroidine, a high affinity and competitive nAChR antagonist, attenuated the enhancement of extracellular DA levels produced by 100 M nicotine alone. These results suggest that local nicotine challenge potentiated the somatodendritic DA release after nicotine preexposure by stimulation of high-affinity nAChRs in the VTA.     

Preparation of a series of sulfated tetrasaccharides from shark cartilage chondroitin sulfate D using testicular hyaluronidase and structure determination by 500 MHz1H NMR spectroscopy

Six tetrasaccharide fractions were isolated from shark cartilage chondroitin sulfate D by gel filtration chromatography followed by HPLC on an amine-bound silica column after exhaustive digestion with testicular hyaluronidase. Their structures were determined unambiguously by one- and two-dimensional 500 MHz¹H NMR spectroscopy in conjunction with HPLC analysis of chondroitinase AC-II digests of the tetrasaccharides. One fraction was found to contain two tetrasaccharide components. All the seven tetrasaccharides shared the common core structure GlcA1-3GalNAc1-4GlcA1-3GalNAc with various sulfation profiles. Four were disulfated comprising of two monosulfated disaccharide units GlcA1-3GalNAc(4-sulfate) and/or GlcA1-3GalNAc(6-sulfate), whereas the other three were hitherto unreported trisulfated tetrasaccharides containing a disulfated disaccharide unit GlcA(2-sulfate)1-3GalNAc(6-sulfate) and a monosulfated disaccharide unit GlcA1-3GalNAc(4-or 6-sulfate). These sulfated tetrasaccharides were demonstrated to serve as appropriate acceptor substrates for serum -N-acetylgalactosaminyltransferase, indicating their usefulness as authentic oligosaccharide substrates or probes for the glycobiology of sulfated glycosaminoglycans.Abbreviations NFU National formulary unit - COSY correlation spectroscopy - HOHAHA homonuclear Hartmann-Hahn - 1D or 2D one- or two-dimensional - IdoA l-iduronic acid - GlcA d-gluco-4-enepyranosyluronic acid - Di-0S GlcA1-3GalNAc - Di-4S GlcA1-3GalNAc(4-sulfate) - Di-4S GlcA1-3GalNAc(4-sulfate) - Di-6S GlcA1-3GalNAc(6-sulfate) - Di-6S GlcA1-3GalNAc(6-sulfate) - Di-diS _d GlcA(2-sulfate)1-3GalNAc(6-sulfate) - Di-diS_E GlcA1-3GalNAc(4, 6-disulfate) - U G, U, 2S, 4S, and 6S represent GlcA, GalNAc, GlcA, 2-O-sulfate, 4-O-sulfate, and 6-O-sulfate, respectively     

Task Relevance Enhances Early Transient and Late Slow-Wave Activity of Distributed Cortical Sources

The primary purpose of these studies was to link together concepts related to attention/working memory and feedforward/feedback activity using MEG response profiles obtained in humans. Similar to recent studies of attention in monkeys, we show early spike-like activity (<200 ms poststimulus), most likely reflecting an early transient excitatory response mixed with feedback influences, followed by slow-wave activity (>200 ms poststimulus) in MEG cortical response profiles evoked by a visual working memory task. We experimentally dissociated the early transient activity from the later sustained activity (predominately feedback) by conducting an auditory size classification task. Words, representing common objects, evoked activity in occipital cortex (presumably due to imagery) even though visual stimuli were not present in this task. The initial spike was absent from the response profile obtained from occipital cortex, leaving only slow-wave activity, thereby allowing us to characterize or profile feedback activity in this situation. Attention or task relevance enhanced the initial spike and slow-wave activity in visually responsive areas. Prefrontal activity, along the superior frontal sulcus, evoked by the working memory task, was active later in time than initial activity in visual cortex and later than the earliest effect of attention modulation in visual cortex.     

Über quantitative Veränderungen „gomoripositiver“ Substanzen in Infundibulum und Hypophysenhinterlappen der Ratte nach beidseitiger Adrenalektomie

Zusammenfassung Bei der normalen weißen Ratte verhält sich die Zona externa des Infundibulum im Gegensatz zur Zona interna infundibuligomorinegativ.Am 7. Tag nach beidseitiger Adrenalektomie treten in der Zona externa gomoripositive Substanzen auf, deren Menge über den 14. Tag nach der Operation hinaus zunimmt.Im supraoptico-hypophysären System ergibt die quantitative Messung eine Entleerung des neurosekretorischen Materials am 3. Tage nach beidseitiger Adrenalektomie. Im Verlauf von 14 Tagen nach dem operativen Eingriff füllt sich das neurosekretorische System wieder bis zu den beim Normaltier ermittelten Werten auf.Die gomoripositiven Granula in der Zona externa inf. sind möglicherweise das morphologische Äquivalent eines Corticotropin-releasing factors.

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On quantitative changes of Gomori-positive substances in the median eminence and neural lobe of the rat hypophysis after bilateral adrenalectomy

Summary In the normal albino rat, the external layer of the median eminence shows a Gomori-negative histochemical reaction as opposed to the internal layer.On the 7th day after bilateral adrenalectomy, Gomori-positive substances appear in the external layer, their amount increasing up to and beyond the 14th day p.o.In the supraoptico-hypophyseal system, quantitative measurements show a depletion of the neurosecretory substance on the 3rd day following bilateral adrenalectomy. This loss of neurosecretory material is restored during the course of 14 days p.o., the amount then corresponding to that found in the normal rat.It is conceivable that the Gomori-positive granules in the outer layer of the median eminence are the morphological equivalent of a CRF.

     

The taxonomic significance of the trunk limbs of the chydoridae (Cladocera)

Summary The differences in the structure of the trunk limbs allow to outline three sections of Chydoridae (see table I and fig. 1), coinciding with the sections distinguished according to the structure of the head pores.

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Chydoridae (Cladocera)

Chydoridae (. ), , .