The growth of cells of ventral sebaceous gland of Rhombomys opimus was studied in diffusion chambers. The surface properties of these cells and intercellular contacts have been examined in the scanning electron microscope. After 10 to 12 days of cultivation the cells formed aggregates showing a recognizable histological pattern (the ventral sebaceous gland). The pituitary and ovarian gland explants had a significant effect on the differentiation and mitotic activity of epithelial cells of the ventral sebaceous gland. Apparently it is the cell surface itself that alters during the active processes of secretion and differentiation.
Nausea of vestibular origin can be used instead of poisoning in the conditioned taste aversion (CTA) paradigm. In an attempt to establish the forms of vestibular stimulation best suited for inducing CTA in rats, effectiveness of 2 h rotation (Exp. 1) was compared with tonal asymmetry elicited by unilateral microinjection of 5.0 microliters of 25% KCl into the vestibular complex (Exp. 2), by unilateral electrical stimulation of vestibular nuclei (100 Hz, 1 ms, 100-200 microA, 15 min--Exp. 3) or by 10 min polarization of labyrinth through electrodes inserted in the external auditory meati (Exp. 4). Nystagmus, deviation of the head and leaning towards the blocked and away from the stimulated side were typical symptoms. When the above stimuli were applied within 10 min after saccharin drinking, galvanic stimulation was ineffective, but electrical stimulation or chemical blockade of vestibular nuclei elicited marked CTA to saccharin, considerably stronger than CTA induced by rotation. It is concluded that direct interference with the activity of vestibular nuclei elicits CTA more effectively than the stimulation of the labyrinth and is, therefore, well suited for the analytical research into the mechanisms of CTA.
The serotoninergic neuron system of the midbrain and hypothalamus was previously shown to inhibit the basal secretion of the TRH-TSH-thyroid axis. The aim of the present study was to investigate the influence of the serotoninergic system on the TSH response of the adenohypophysis to specific loads. Serum TSH levels were determined 7 days after thyroidectomy or the beginning of thiouracil administration. Animals were simultaneously treated either by intrahypothalamic implantation of serotonin-containing needles or by intraventricular or daily subcutaneous injections of the same drug. The thiouracil-induced goitre formation and increase in serum TSH concentration were significantly diminished by serotonin treatment. Similarly, the thyroidectomy-induced rapid rise in TSH blood level was also remarkably inhibited in the serotonin-treated animals. Serotonin was proved to influence rather TRH-output than pituitary TSH secretion, since exogenous TRH, injected to serotonin-pretreated animals had the same TSH-mobilizing potency as found in the not premedicated group. It is concluded that besides the inhibition of the basal secretion of the TRH-TSH-thyroid axis by serotonin, there is an integrative role of the serotoninergic system in the mediation of the reactivity of this circuit in reply to specific influences loading pituitary-thyroid function.
An account of the origin of the term liaison brain leads on to an historical account of its usage, particularly in voluntary movement. Empirical evidence was provided by the readiness potential of Kornhuber and associates, which even indicated a key role for the supplementary motor area, SMA. It was found by Brinkman and Porter that in voluntary movement many neurones of the SMA were activated probably up to 200 msec before the pyramidal tract discharge. Then came the (133)Xe investigations of regional cerebral blood flow by Roland and associates to reveal that there was neuronal activity in the SMA of both sides during a continued series of voluntary movements, and that his even occurred when the movement was being thought of but not executed. The microstructure and connectivities of the SMAS are considered in relationship to its proposed key role in being excited by the mental act of intention and then calling up the appropriate motor programs to give the desired movement: each mental intention would act on the SMA in a specific manner; the SMA has an 'inventory' and the 'addresses' of stored subroutines of all learnt motor programs and so is able to institute the desired movement by its neuronal connectivites. In conclusion there is a general account of the concept of the liaison brain both for intention and perception.
Goal-directed movements, such as punching and pointing, need preprogramming of postural support and visual control. These processes are recorded in man by EEG, EMG, oculogram, and a platform. The earliest cerebral correlate of voluntary action is the Bereitschaftspotential (readiness potential) or, after a trigger signal, the expectancy wave (CNV). These bilateral negative potential shifts increase to a Zielbewegungspotential (aiming potential) when a goal-directed movement is made, and end with a positive shift, when the goal is reached. During these cerebral potentials an attentive eye saccade is directed towards the target and an ordered sequence of bilateral muscle activations follows. This coordinated motor activity in trunk and leg muscles corresponds to a readiness innervation that prepares body posture and balance. It precedes the final aimed movement of the arm towards the target and postural adjustments such as the compensation of body and head rotation by the vestibular-ocular reflex. The temporal order of the cerebral, oculomotor and muscular events is schematized for punching and pointing movements in a figure. The limits of conscious control and the necessity of automatized learning for voluntary skilled movement under visual control are discussed. Some speculations are made about a possible origin of slow potential shifts by surface negative dipoles in columnar modules of the parasagittal cortex during the programming and monitoring of aimed motion.
The anterograde transport of horseradish peroxidase was used to stain nerve fibers in the hypothalamic median eminence of the rat. Bundles of commissural fibers were found coursing in the subependymal layer. They approach the median eminence along the basal surface of the diencephalon, and seem to terminate contralaterally in the medio-basal hypothalamus. The relatively thick fibers of the magnocellular fiber system were seen in the internal zone. Along their rostro-caudal trajectory the fibers join into bundles which surround elongated fields. The varicose fibers of the parvicellular system run rostro-caudally in the dorsal part of the external (palisade) zone, while they become randomly oriented more ventrally, i.e. adjacent to the portal capillaries. It is tentatively suggested that tanycyte processes around the median eminence form a barrier system localizing the substances secreted by the nerve terminals of the parvicellular fiber system. Tanycyte processes within the median eminence seem to divide the palisade zone into rostro-caudally elongated compartments allowing only transverse diffusion in the extracellular space.
Using the double ink-filling technique the arteries and veins of the lateral hypothalamus are described in detail. This region occupied mainly by the fibres and interposed cells of the medial forebrain bundle is supplied by some own arteries and branches of the large basal vessels. Most of the arteries running to the rostral part of the lateral hypothalamus originate from the internal carotid, others belong to the anterior and middle cerebral arteries. Blood supply of the middle part comes from the middle hypothalamic and three tuberal arteries. All arteries of the caudal part originate from the posterior communicans. The abundant drainage of the lateral hypothalamus is collected by the basal and anterior interpeduncular veins from the rostral two-thirds and the caudal one-third, respectively.
The paper presents morphological evidence that upon deafferentation small Golgi cells and granule cells of the cerebellar cortex as well as geniculo-cortical relay cells of the Lateral Geniculate Nucleus develop presynaptic sites on their otherwise exclusively postsynaptic dendrites. The new synapses are, therefore, mostly dendro-dendritic, a logical consequence of the fact that in the absence of axonal sprouting in the two regions, the reactive synaptogenesis in the cerebellar cortex and LGN is accomplished by the participation of the (newly formed) presynaptic dendrites.
Double retrograde tracer experiments (HRP, 3H-apo-HRP) were performed to investigate the organization of thalamic neurons projecting to visual cortical areas. The distribution of labelled cells was in agreement with previous findings, showing a topographical and overlapping pattern of these thalamocortical projections. If a restricted thalamic region in the lateralis posterior-pulvinar complex projected into more than one cortical area, the projection neurons to each individual area were intermingled. However, each neuron projected only into one area and there was no anatomical evidence for the presence of neurons projecting to more than one cortical area.
Golgi and electron microscopic observations of the neostriatum of macaque monkeys reveal the presence of thin axons of extrinsic origin which produce a profuse arborization of very fine beaded branches. The varicosities contain pleomorphic synaptic vesicles, and may form strongly asymmetric axospinous synapses. Immunocytochemical methods utilizing an unlabeled antibody against serotonin followed by peroxidase-antiperoxidase complex and further histochemical visualization demonstrate that some elements conforming to the above description exhibit specific immunoreactivity. Relatively few of the labeled profiles form synapses and did so with small dendritic spines. In these cases the membrane specializations are strongly asymmetric. The neuropil also contains many unstained elements of similar morphology. The findings provide the morphologic features of serotoninergic axons in the neostriatum. Their properties may be shared by other monoaminergic afferents. It is suggested that serotonin is released as a neurotransmitter from synapsing boutons, and as a neuromodulator from non-synapsing varicosities. This distinction may correlate with the serotonin receptors 1 and 2 which apparently are responsible for excitatory and inhibitory actions respectively.
In rabbits, the right hind limb was immobilized by means of plaster cast for 1, 2, 4 or 6 weeks and the activities of some metabolic enzymes: GOT, GPT, LDH, aldolase and acid phosphatase (in part of lysosomal origin), were examined in the slow m. soleus, and in the fast m. gastrocnemius. The former muscle is known to have mainly an oxidative, while the latter mainly a glycolytic type of metabolism. The activities of enzymes highly involved in the metabolism of the muscle diminished for a certain time during atrophy, then a relative rise occurred. Acid phosphatase activity likewise decreased after an initial relative increase. Reduction of enzymatic activities is explained by the activation of proteolytic enzymes, on the basis of measurements performed in these experiments and of results published by others. The decrease of enzymatic activity was more marked in the muscle which in normal state exhibits higher activity than in the other type of muscle studied. Thus, in the gastrocnemius a high rate of degradation of glycolytic enzymes was observed, while in the soleus degradation of oxidative enzymes prevailed. This phenomenon leads to the dedifferentiation of the muscle cell during immobilization.
The effects of 10 ppm CuSO4, ZnCl2 on the blood glucose level and serum LDH, GOT, GPT activities of three fish species (carp, silver carp, European wels) were measured. CuSO4 increased the blood glucose level, LDH, GOT and GPT activities in the three species in the following order: silver carp greater than carp greater than European wels. ZnCl2 did not alter the same levels. Our results showed that CuSO4, and presumably several anthropogenic agents, damaged the different fish species specifically and caused different stress effects depending on the fish species.
Studies on fluorescent histochemical localization of monoamines in strips of connective tissue teared off the electric organ of Torpedo marmorata revealed an extensive system of yellow fluorescent nerve fibres. No green fluorescent (catecholamine-containing) axons were found in this region. The significance of the presence of indole-containing axons in the connective tissue of the electric organ is in accordance with previous findings on a high level of serotonin in the Torpedo electric organ and contradicts the general assumption that the electric tissue is a source of purely cholinergic nerve endings.
