Horseradish Peroxidase Method Research Articles

Two movement-related foci in the primate cingulate cortex observed in signal-triggered and self-paced forelimb movements

1. Single-unit activity in the cingulate cortex of the monkey was recorded during the performance of sensorially (visual, auditory, or tactile) triggered or self-paced forelimb key press movements. 2. Microelectrodes were inserted into the broad rostrocaudal expanse of the cingulate cortex, including the upper and lower banks of the cingulate sulcus and the hemispheric medial wall of the cingulate gyrus. 3. A total of 1,042 task-related neurons were examined, the majority of which were related to the execution of the key press movements. In greater than 60% of them, the movement-related activity preceded the activity in the distal flexor muscles. 4. The movement-related neurons were distributed, in two foci, in the posterior and anterior parts of the cingulate cortex, both including the upper and lower banks of the cingulate sulcus. The posterior focus was found to largely overlap the area projecting to the forelimb area of the primary motor cortex by the use of the horseradish peroxidase (HRP) method. 5. About 40% of the cingulate cortical neurons showed equimagnitude responses during the signal-triggered and self-paced movements. The neurons exhibiting a selective or differential response to the self-paced motor task were more frequently observed in the anterior than in the posterior cingulate cortex. 6. The long-lead type of changes in activity, ranging from 500 ms to 2 s, were observed mainly before the self-paced and, much less frequently, before the triggered movements. They were particularly abundant in the anterior cingulate cortex. 7. Only a few of the neurons showed activity time-locked to the onset of the sensory signals. 8. These observations indicate that the anterior and posterior parts of the cingulate cortex are distinct entities participating in the performance of limb movements, even if the movements are simple, such as those in this study.

Retinofugal and Retinopetal Projections in the Green Sunfish, <i>Lepomis cyanellus</i> (Part 2 of 2)

The retinofugal and retinopetal connections in the green sunfish were studied by autoradiographic and horseradish peroxidase methods. All retinofugal fibers decussate in the optic chiasm. Some fibers project to contralateral preoptic and hypothalamic nuclei while others recross to project to the comparable ipsilateral nuclei. Contralaterally, the medial optic tract projects to the periventricular thalamic and pretectal nuclei and, sparsely, to the rostral optic tectum. The dorsal optic tract projects to the parvocellular portion of the superficial pretectal nucleus, the central pretectal nucleus, nucleus corticalis, and the rostral portion of the optic tectum. The ventral optic tract primarily projects to the caudal portion of the optic tectum, giving off fibers in route to innervate various nuclei, including the parvocellular superficial pretectal nucleus and the dorsal and ventral accessory optic nuclei. The axial optic tract projects to the dorsal accessory optic nucleus, the central pretectal nucleus, and the caudal optic tectum. Retinal fibers reach the ipsilateral thalamus, pretectum and other sites via a redecussation through the posterior commissure. From outgroup analysis it is concluded that such redecussating fibers are an independently derived character within actinopterygians and are homoplasous to nondecussating ipsilateral retinal projections in other vertebrates. Neurons retrogradely labeled with horseradish peroxidase were found to form a rostrocaudal column from the olfactory bulb and nerve through the ventral telencephalon to caudal diencephalic levels along the medial aspect of the optic tract. It is possible that all these neurons consist of one population of migrated ganglion cells of the nervus terminalis.

Retinofugal and Retinopetal Projections in the Green Sunfish, <i>Lepomis cyanellus</i>

The retinofugal and retinopetal connections in the green sunfish were studied by autoradiographic and horseradish peroxidase methods. All retinofugal fibers decussate in the optic chiasm. Some fibers project to contralateral preoptic and hypothalamic nuclei while others recross to project to the comparable ipsilateral nuclei. Contralaterally, the medial optic tract projects to the periventricular thalamic and pretectal nuclei and, sparsely, to the rostral optic tectum. The dorsal optic tract projects to the parvocellular portion of the superficial pretectal nucleus, the central pretectal nucleus, nucleus corticalis, and the rostral portion of the optic tectum. The ventral optic tract primarily projects to the caudal portion of the optic tectum, giving off fibers in route to innervate various nuclei, including the parvocellular superficial pretectal nucleus and the dorsal and ventral accessory optic nuclei. The axial optic tract projects to the dorsal accessory optic nucleus, the central pretectal nucleus, and the caudal optic tectum. Retinal fibers reach the ipsilateral thalamus, pretectum and other sites via a redecussation through the posterior commissure. From outgroup analysis it is concluded that such redecussating fibers are an independently derived character within actinopterygians and are homoplasous to nondecussating ipsilateral retinal projections in other vertebrates. Neurons retrogradely labeled with horseradish peroxidase were found to form a rostrocaudal column from the olfactory bulb and nerve through the ventral telencephalon to caudal diencephalic levels along the medial aspect of the optic tract. It is possible that all these neurons consist of one population of migrated ganglion cells of the nervus terminalis.

Retinal Projections in the Freshwater Butterfly Fish, <i>Pantodon buchholzi</i> (Osteoglossoidei) (Part 2 of 2)

The freshwater butterfly fish, Pantodon buchholzi, is a member of the most primitive radiation of teleosts. The retinofugal projections were studied in this fish with autoradiographic and horseradish peroxidase (HRP) methods, and the cytoarchitecture of the retinorecipient regions in the diencephalon and pretectum was analyzed with Bodian-, cresylecht-violet- and acetylcholinesterase-reacted sections. The rostral diencephalon of Pantodon contains a large retinorecipient nucleus, not previously identified in any other fish, i.e. nucleus rostrolateralis. Other nuclei that are described correspond to those previously recognized in other species. The majority of retinorecipient nuclei are positive for acetylcholinesterase, particularly those in the pretectum, as has been found in other species of teleosts. Most of the retinofugal fibers decussate in the optic chiasm. Some fibers project via the axial optic tract to preoptic nuclei and a region in the rostral hypothalamus. Fibers leave the medial optic tract to terminate in nucleus rostrolateralis and in dorsal and ventral thalamic nuclei, accessory optic and tubercular nuclei, periventricular and central pretectal nuclei, and sparsely in the deep tectal fascicle and terminal field. Dorsal optic tract fibers project to the dorsal accessory optic nucleus, superficial and central pretectal nuclei, and superficial and deep tectal layers. Ventral optic tract fibers project to the superficial pretectum, accessory optic nuclei, posterior tuberculum, nucleus corticalis in the central pretectum, and superficial tectal layer. Fibers that remain in the ipsilateral optic tract project to most of the targets reached by contralaterally projecting fibers. A few fibers in the contralateral medial optic tract redecussate via the posterior commissure to reach the ipsilateral periventricular pretectum. No labeled retinopetal cells caudal to the olfactory bulb were identified in any of the HRP cases.

Retinal Projections in the Freshwater Butterfly Fish, <i>Pantodon buchholzi</i> (Osteoglossoidei) (Part 1 of 2)

The freshwater butterfly fish, Pantodon buchholzi, is a member of the most primitive radiation of teleosts. The retinofugal projections were studied in this fish with autoradiographic and horseradish peroxidase (HRP) methods, and the cytoarchitecture of the retinorecipient regions in the diencephalon and pretectum was analyzed with Bodian-, cresylecht-violet- and acetylcholinesterase-reacted sections. The rostral diencephalon of Pantodon contains a large retinorecipient nucleus, not previously identified in any other fish, i.e. nucleus rostrolateralis. Other nuclei that are described correspond to those previously recognized in other species. The majority of retinorecipient nuclei are positive for acetylcholinesterase, particularly those in the pretectum, as has been found in other species of teleosts. Most of the retinofugal fibers decussate in the optic chiasm. Some fibers project via the axial optic tract to preoptic nuclei and a region in the rostral hypothalamus. Fibers leave the medial optic tract to terminate in nucleus rostrolateralis and in dorsal and ventral thalamic nuclei, accessory optic and tubercular nuclei, periventricular and central pretectal nuclei, and sparsely in the deep tectal fascicle and terminal field. Dorsal optic tract fibers project to the dorsal accessory optic nucleus, superficial and central pretectal nuclei, and superficial and deep tectal layers. Ventral optic tract fibers project to the superficial pretectum, accessory optic nuclei, posterior tuberculum, nucleus corticalis in the central pretectum, and superficial tectal layer. Fibers that remain in the ipsilateral optic tract project to most of the targets reached by contralaterally projecting fibers. A few fibers in the contralateral medial optic tract redecussate via the posterior commissure to reach the ipsilateral periventricular pretectum. No labeled retinopetal cells caudal to the olfactory bulb were identified in any of the HRP cases.

Connections of the insular cortex in kittens: An anatomical demonstration with wheatgerm agglutinin conjugated to horseradish peroxidase technique

The postnatal development of the afferent and efferent connections of the feline insular cortex was investigated using wheat germ agglutinin conjugated to horseradish peroxidase method. The overall pattern of connections was found to be substantially the same as that observed in adults. In the cortex, anterograde and retrograde labeling was found in the presylvian sulcus, cingulate gyms, cruciate sulcus, medial prefrontal area, lateral suprasylvian cortex, and posterior rhinal sulcus. Subcortical regions containing label included the lateralis medialis-suprageniculate nuclear complex, ventral medial thalamic nucleus, claustrum, lateral amygdaloid nucleus, hypothalamus, and raphe nuclei. In addition, axonal labeling was seen in the striatum, superior colliculus, and pontine nuclei.In contrast, the insular associational projections in kittens differed markedly from those found in adults. In the early postnatal period (1–14 days), dense terminal labeling was found in the cortical layers I, V and VI as well as in the underlying white matter, whereas only moderate to sparse labeling was observed in layers II, III and IV. By four-weeks, an adult-like distribution of terminals was present in each cortical areas: labeling was found mainly in layers I, II, III and IV, with less in layers V and VI.The present results suggest that the basic framework of the insular connections is formed prenatally and that the fine tuning of the axonal terminals and the formation of synapses occurs mainly during the first four postnatal weeks.

Immunobinding assayを用いたマイコプラズマ肺炎の抗原検出による早期診断の検討

The possibility of rapid diagnosis of Mycoplasma pneumoniae infection by immunobinding assay is described. Immunobinding assay which was developed by Kotani and McGarrity is a simple and rapid method for identification of mycoplasmas. Small amounts of antigen were spotted onto the nitrocellulose membrane. It was treated with a specific rabbit antisera against M. pneumoniae. The antigen-antibody complex was visualised with the avidin-biotin horseradish peroxidase method. Cross reaction was seen between M. pneumoniae and M. genitalium. Throat swabs from hamsters infected with M. pneumoniae were positive on 7th and 14th day after infection. Although the cross reaction was seen between M. pneumoniae and M. genitalium, this method could be useful for rapid diagnosis of M. pneumoniae infection.

Sensory neurons and motoneurons of the jaw-closing reflex pathway in rats: a combined morphological and physiological study using the intracellular horseradish peroxidase technique

Motoneurons and muscle spindle afferents of the rat masseter muscle were physiologically and morphologically characterized. Their soma-dendritic morphology and axonal course were investigated using the intracellular horseradish peroxidase method. Following electrical stimulation of the masseter nerve, individual motoneurons were identified by antidromic all-or-none action potentials and individual sensory neurons by orthodromic action potentials. Using threshold separation an excitatory input from muscle spindles to a masseter motoneuron was demonstrated. The short latency difference of 0.34 ms between the mean orthodromic response in the sensory neurons and the beginning of the synaptic potential in the masseter motoneuron suggests a monosynaptic connection between the spindle afferents and the motoneurons. Following intrasomatic horseradish peroxidase injection large multipolar cell bodies of masseter motoneurons were found within the motor nucleus. Their positions corresponded to the topographic organization of the motor trigeminal nucleus as described in retrograde tracing studies. Dendrites of masseter motoneurons were complex and could be found far beyond the nuclear borders. Distal dendrites extended to the mesencephalic trigeminal nucleus, the supratrigeminal nucleus, the lateral lemniscus and the reticular formation. Within the reticular formation dendrites were seen in the intertrigeminal nucleus and the peritrigeminal zone. Unipolar cell bodies of muscle spindle afferents were found in the mesencephalic trigeminal nucleus after intra-axonal injection of horseradish peroxidase. For all reconstructed sensory neurons a similar axonal course was found. Axonal terminals were found ipsilateral in the motor trigeminal nucleus, indicating a direct connection between sensory neurons and motoneurons. Further collaterals were found ipsilateral in the supratrigeminal nucleus and caudal to the motor trigeminal nucleus in the parvocellular reticular nucleus alpha. Since the latter termination areas are important for bilateral control of jaw-movements, the muscle spindle afferents are likely to participate not only in a monosynaptic motor reflex, but also in more complex neuronal circuits involved in jaw-movements.

Quantitative distribution of descending tectal efferent cells in salamanders

In salamanders of the species Salamandra salamandra, Pleurodeles waltl, and Plethodon jordani, tectal efferent neurons projecting to the bulbar reticular formation show a stereotyped distribution as revealed by the horseradish peroxidase (HRP) method. The density of these cells increases toward caudal tectal levels reaching its maximum at the isthmic region. Neurons with ipsilaterally descending axons constitute 60–87% and are concentrated in the dorsomedial and ventrolateral sector of the tectal hemisphere, with only few neurons in the intermediate part. The contralaterally descending neurons are concentrated in the lateral sector. This pattern is assumed to reflect a motor map in the coordinates of the salamander neck muscle system.

Cytoarchitecture and fiber connections of the nucleus lateralis valvulae in the carp (Cyprinus carpio)

The cytoarchitecture and fiber connections of the nucleus lateralis valvulae of the carp (Cyprinus carpio) were studied by Nissl, Bodian, Golgi, and horseradish peroxidase methods. Chief cells composing the nucleus lateralis valvulae (NLV) are small and granular, and their axons terminate in the cerebellum. These neurons have no dendrite, and the cell body is enveloped in a single terminal of afferent fibers to the NLV. In order to observed local cell clustering, the NLV was three-dimensionally reconstructed with the aid of a computer image analysis system. Afferent sources to the NLV were the nucleus pretectalis superficialis pars magnocellularis (Northcutt and Braford, '84: Brain Res. 296:181-184), nucleus ventromedialis thalami (Ito et al., '86: J. Comp. Neurol 250:215-227), and the inferior lobe. The NLV projects to the inferior lobe and the cerebellum. In particular, the cerebellar projections were strong and topographically arranged. Some larger neurons lying just beneath the NLV, some of which were intermingled with the NLV neurons, projected to the torus longitudinalis. On the basis of the local cell clustering as well as NLV-cerebellar connections, three subdivisions of the NLV could be recognized, i.e., anterior, central, and posterior portions. The posterior portion was further subdivided into lateral and medial parts.

The trigeminal sensory innervation to the middle ear, eustachian tube, and pharynx: A study by the horseradish peroxidase tracer method

The trigeminal sensory innervations to the middle ear, the eustachian tube, and the pharynx were examined using the horseradish peroxidase (HRP) method in cats. After HRP application to the middle ear and the eustachian tube, HRP-labeled cells were found mainly in the posterolateral portion and the anteromedial portion of the trigeminal ganglion, respectively. In the case of injection into the epipharynx and the mesopharynx, HRP-labeled cells were found in the anteromedial portion and the posterolateral portion, respectively. HRP-labeled cells were hardly observed when HRP was applied to the hypopharynx. These results indicate that trigeminal nerve sensory fibers branch to the middle ear, including the eustachian tube, epipharynx, and mesopharynx.

Visual inputs to the dorsocaudal fastigial nucleus of the cat cerebellum. An experimental study using single unit recordings and horseradish peroxidase labelling.

Visual afferents to the cat fastigial nucleus (FN) have been studied with single unit recordings and horseradish peroxidase techniques. A total of 158 cells responding to electrical stimulation of the optic chiasm (OCh) were extracellularly recorded from the dorsocaudal part of the FN. They were classified into three groups: type-1 cells (48%) which showed early suppression and late facilitation; type-2 cells (38%) which showed early facilitation and late suppression; type-3 cells (14%) which exhibited long lasting suppression with no signs of facilitation. Eight of 32 cells tested showed the same response patterns to photic stimulation as to electrical stimulation of the OCh. None of the cells responding to electrical and photic stimulation, however, were found in the rostral and ventral parts of the FN. Furthermore, 29 cells which responded to electrical stimulation of the OCh were tested for responses to moving pattern stimulation. Seven (4 type-2 cells and 3 type-3 cells) of the 29 cells showed clear modulation, reflecting the velocity component of a horizontally moving pattern. However, none of 13 type-1 cells tested exhibited apparent modulation in relation to movement of the pattern. In order to trace the possible pathways mediating visual signals to this part of the FN, the horseradish peroxidase (HRP) method was used. Injection of HRP into the caudal FN resulted in the labelling of many cells, predominantly in the medial (M) and the descending (D) vestibular nuclei and in lobules VI and VII of the cerebellar vermis. A series of experiments further indicated the presence of possible pathways propagating visual signals to the caudal FN. The main routes are: 1) via the nucleus of the optic tract (NOT)--the dorsal part of the medullary reticular formation--the M and the D vestibular nuclei--to the FN, and 2) via the superior colliculus--the pontine nuclei--vermal lobules VI and VII--to the FN. The different physiological response patterns of FN cells may indicate that several types of visual signals involved with visually guided movements impinge upon the dorsocaudal FN.

Representation of the tensor veli palatini muscle in the trigeminal motor nucleus of the Japanese monkey (Macaca fuscata)

Distribution of motoneurons supplying the tensor veli palatini (TVP) muscle was examined in the Japanese monkey (Macaca fuscata) by the retrograde horseradish peroxidase (HRP) method. Neurons labeled with HRP which was injected into the tensor veli palatini muscle were seen in the ventromedial aspects of the dorsolateral division of the trigeminal motor nucleus, at all rostrocaudal levels of the trigeminal motor nucleus. The vast majority of these TVP motoneurons were distributed around the margin, especially the dorsal margin, of the cluster of motoneurons which innervate the lateral pterygoid muscle.

A morphological analysis of neurons in the lateral parabrachial nucleus: An intracellular horseradish peroxidase study in the rat

Neurons in the lateral parabrachial nucleus (LPB) of the rat were analyzed by the intracellular horseradish peroxidase method. Sixteen LPB neurons were successfully labeled with HRP injected intracellularly. HRP-labeled LPB neurons were divided into type I (7 neurons) and type II (9 neurons) LPB neurons. Type I LPB neurons, which were activated antidromically by stimulation of the ipsilateral posteromedial ventral nucleus of the thalamus, had long dendrites and a long axon. Type II LPB neurons, which were not activated antidromically by the stimulation of the thalamus, had short dendrites and a short axon. It was concluded that type I LPB neurons were projection neurons, while type II LPB neurons were local circuit neurons.

Active Oxygen‐mediated Cytotoxic and Antitumor Actions of Streptococcal Cytotoxic Protein

Streptococcal cytotoxic protein (SCP), obtained from the cell‐free extract of Streptococcus pyogenes, inhibited the uptake of [methyl‐3H]thymidine by Ehrlich ascites carcinoma cells depending on the concentration of fetal calf serum (FCS) added to the culture medium. The same results were found using sera from different animals. The inhibitory activity of SCP was completely suppressed by catalase but not by hydroxyl radical scavengers or superoxide dismutase. The antitumor activity of SCP in tumor‐bearing mice was inhibited by administration of catalase together with SCP. SCP enzymatically produced hydrogen peroxide in the presence of FCS as detected by the 2,2′‐azino‐di‐[3‐ethyl‐benzothiazoline‐(6)‐sulfonic acid]/horseradish peroxidase method. The kinetic parameters, Km and Vmax, for hydrogen peroxide production of SCP were 2.13% FCS and 0.53 nmol/min/μg SCP, respectively. These results indicate that SCP is an enzyme which produces hydrogen peroxide and exerts potent cytotoxic and antitumor effects using an active oxygen species, hydrogen peroxide, produced by the enzymatic reaction of SCP with an unknown substrate contained in FCS or sera from various animals and molecular oxygen.

Infrahyoid and accessory motoneurons in the japanese monkey (Mascaca fuscata)

The segmental and topographical organization of motoneurons innervating the infrahyoid (IH) and the spinal accessory (AC) muscles was studied in the Japanese monkey (Macaca fuscata) with the retrograde horseradish peroxidase (HRP) method after application of HRP to the peripheral nerve branches supplying the IH and AC muscles. IH motoneurons constitute two distinct slender cell columns, a longer medial and a shorter lateral one. The medial cell column extends from the most caudal level of the hypoglossal nucleus to the lower levels of the second cervical (C2) cord segment. In the medial column, motoneurons supplying the sternohyoid and sternothyroid muscles are distributed at the medullary and C1 levels, while those innervating the omohyoid muscle are primarily distributed at the C2 level. The lateral cell column consists of motoneurons supplying the thyrohyoid muscle and extends from the most caudal level of the hypoglossal nucleus to the middle levels of the C1 cord segment. Axons of thyrohyoid motoneurons follow a dorsomedially directed bent emergent course, making a hairpin turn. AC motoneurons supplying the sternocleidomastoid (SC) and trapezius (TZ) muscles form a single slender cell column extending from the most rostral level of the pyramidal decussation to the middle levels of the C6 cord segment. SC motoneurons are distributed from the most rostral level of the pyramidal decussation to the middle levels of the C3 cord segment, while TZ motoneurons are distributed from the upper levels of the C2 cord segment to the lower levels of the C6 cord segment. At the levels of the C2 and C3 cord segments, both SC and TZ motoneurons are distributed in the AC cell column; the cluster of SC motoneurons is located dorsomedial to that of TZ motoneurons.

Central Fiber Connections of the Vestibulo-Autonomic Reflex Arc in Cats

The fiber connections associated with the vestibulo-autonomic reflex in the brain stem were investigated in cats using electrophysiological and horseradish peroxidase (HRP) methods. When the peripheral labyrinth was stimulated, the stomach constricted, and in some cases this constriction was strong and lasted for a relatively long period. This phenomenon was interpreted as a kind of vomiting triggered by the vestibuloautonomic reflex. When the electrical stimulus was applied to the peripheral labyrinth, the solitary tractus nuclear (SN) neurons, where the vagal nerve cell bodies exist, fired spikes with short latencies. When HRP was injected into the SN region, HRP-labelled cells were found in the parvocellular reticular nucleus (PC) and vestibular nuclei (VN). When HRP was injected into the PC region, HRP-labelled cells were found in the VN. These electrophysiological and histological results indicate the existence of the following fiber connections: (i) vestibular organs-VN-SN-(vagal nerve)-stomach, (ii) vestibular organs-VN-PC-SN-(vagal nerve)-stomach, associated with the vestibulo-autonomic reflex.

Afferent connections of the prelunate visual association cortex (areas V4 and DP)

The afferent and efferent connections of the prelunate visual association area V4 of macaque monkeys were investigated by means of the horseradish peroxidase (HRP) method. The specific thalamic afferents from the dorsolateral segment of the medial pulvinar and the lateral segment of the inferior pulvinar were topographically organized. A band of cells was labelled in the intralaminar nuclei (nucl. centr. med. and lat., reaching into LD and the most dorsal part of VL), and a few cells in the interlaminar layers of the lateral geniculate body. Other diencephalic afferents included the claustrum, the nucleus basalis Meynert and the pars compacta of the substantia nigra. Ipsilateral cortical areas which projected into V4 included area 18 (V2), the inferior parietal cortex, the anterior and posterior parts of the superior temporal sulcus, the frontal eye fields and the temporo-basal association cortex on the lateral half of the parahippocampal gyrus and around the occipito-temporal sulcus. In the contralateral cortex, discontinuous regions in areas V4 and V5 on the prelunate gyrus and some cells at the 17/18-border were labelled. All regions in which labelled cells were found and, in addition a restricted region in the dorsal cap of the head and the tail of the caudate nucleus showed fibre and terminal labelling. In addition mesencephalic afferents and efferents were identified but not investigated in detail. An attempt to estimate the quantitative contribution of the various afferent systems to the prelunate cortex was made by counting the labelled cells in the different areas. The afferent and efferent organization of the prelunate visual association area indicates that it is incorporated in a network of cortical and subcortical regions involved in various aspects of visual behavior.

Ultrastructural differences between smooth and thorny gonadotropin-releasing hormone neurons

It has been suggested that gonadotropin-releasing hormone neurons with irregular contours receive more synaptic input than do those with smooth contours. To test this hypothesis, a morphometric analysis of gonadotropin-releasing hormone neurons of differing shapes was made. Male Sprague-Dawley rats were perfused and 40-μm tissue sections from the preoptic area were treated for the demonstration of gonadotropin-releasing hormone immunoreactivity, using the avidin-biotin horseradish peroxidase method with 3,3'-diaminobenzidine as the chromogen. Gonadotropin-releasing hormone neurons with either a smooth or a highly irregular outline, sampled at three depths ultrastructurally, were compared for density of synaptic innervation and for relative content of various subcellular organelles. Point counting stereology comparisons of five gonadotropin-releasing hormone neurons of the two shapes in four rats revealed that smooth neurons contained less cytoplasm than “thorny” neurons, but the size of their nuclei was the same. There were more and larger nucleoli in smooth cells. Thorny neurons contained more Golgi apparatus and more mitochondria, but the amount of rough endoplasmic reticulum was the same in neurons of the two morphological types. There was no difference in the incidence of synapses or in the density of synaptic input as measured per unit of neuronal membrane in smooth and thorny gonadotropin-releasing hormone neurons. These results suggest that smooth-contoured gonadotropin-releasing hormone neurons may be more actively transcribing a message while thorny neurons are more actively engaged in peptide processing and packaging. In that the density of synaptic input was the same, these apparent functional differences among gonadotropin-releasing hormone neurons of differing shapes may be independent of synaptic influences; but this must be tested by chemical characterization of the synapses.

Connectivities of the striatal grafts in adult rat brain: a rich afference and scant striatonigral efference

Previous reports from this laboratory have indicated that fetal rat striatal grafts have the major types of neuronal and glial components known to be involved in Huntington's chorea. In this study a number of major afferent and efferent innervations seen in normal striatum were examined in the striatal grafts and were compared with embryonic striatal afferents. First, using immunocytochemistry and histochemistry, the host serotonergic (5-HT), dopaminergic (DA, stained with anti-tyrosine hydroxylase (TH) antiserum), and acetylcholinesterase (AChE) fibers exhibited vigorous growth into the grafts implanted in neostriatum, lateral ventrice, globus pallidus or substantia nigra within a period of 6 and 10 weeks. Individual characteristic terminal patterns formed in striatal grafts: 5-HT fibers were diffused; TH fibers became heavily packed, and AChE fibers were patchy. This peculiar patternization of 5-Ht and TH growth into striatal graft appeared to be a recapitulation of the normal 5-HT and TH growth into striatum in the embryonic stage. However, a significantly show (6 week) onset of adult 5-HT and TH ingrowth into the fetal graft was noted, as compared with that of normal embryonic development (5–6 days from the appearance of 5-HT and TH neurons). With the anterograde-transport marker Phaseolus vulgaris agglutinin leuca method, host cortical neurons also projected to the graft, but in limited numbers. Finally, with the retrograde-transport marker (horseradish peroxidase method, the grafts implanted in neostriatum were found incapable of sending fibers to a major, distal target, substantia nigra. In a current evaluation of striatal transplants, it is shown that major input to the graft can be achieved over time, but output to the distal nigra seems an unrealistic expectation. These data suggest that: (1) the fetal brain tissue was found to be a strong stimulant for sprouting or regeneration of adult nerve fibers; (2) a number of functional recoveries reported on the tested behavior paradigm in this grafting model could be due to the survival of striatal graft and the establishment of input circuitries; further, (3) the data illustrate the necessity of seeking a bridge from the striatal transplant to the host nigra. If a proper functional recovery in Huntington's chorea requires complete striatonigral circuitry, then such a bridge is worthy of a major investigation.