大白鼠上丘传入性联系的HRP法研究

将HRP溶液(33％)注射到21只成体大白鼠的一侧上丘,存活1～2天后,脑切片作DAB或TMB反应,在另一侧上丘及其它脑区观察标记的神经元,结果如下: 1.当注射的深度达到上丘中间灰层或其以下各层时,无论注射点位于上丘的吻、尾端或其之间,标记神经元在另一侧上丘的区域分布与注射的HRP位置大体对应;当注射的深度较浅,即在视觉层及其以上各层时,在对侧上丘未观察到标记的神经元。 2.在上丘的带状层和表面灰层未发现标记的细胞。标记细胞在中间灰层(SGI)最多(53.6％),视觉层为16.5％,深部各层(SGI及其以下各层)标记细胞占标记细胞总数的83.5％。 3.根据标记神经元的形态分为:垂直的梭形神经元,水平的梭形神经元和多极神经元。它们的分布无明显规律。 4.除在同侧的视皮层观察到大量的标记神经元外,在两侧的下丘、外侧丘系背核和丘系旁核、黑质及外侧被盖核、同侧的外膝体腹核、对侧的前顶盖区及网状结构中都发现了标记的神经元。     

Some topographical connections of the striate cortex with subcortical structures in Macaca fascicularis

Summary Subcortical connections of the striate cortex with the superior colliculus (SC), the lateral pulvinar (Pl), the inferior pulvinar (Pi) and the dorsal lateral geniculate nucleus (LG) were studied in the macaque monkey, Macaca fascicularis, following cortical injections of tritiated proline and/or horseradish peroxidase. All four structures were shown to receive topographically organized projections from the striate cortex. The exposed surface of the striate cortex was found to be connected to the rostral part of the SC and the caudal part of the LG. Injections of the exposed striate cortex close to its rostral border resulted in label in adjoining parts of the Pl and Pi. The ventral half and dorsal half of the calcarine fissure were connected with the medial and lateral parts of the SC, the ventrolateral and dorsomedial portions of the Pl and Pi and the lateral and medial parts of the LG, respectively. Injections located at the lateral posterior extreme of the calcarine fissure resulted in label at the optic disc representation in the LG. The horseradish peroxidase material demonstrated that LG neurons in all laminae and interlaminar zones project to the striate cortex.Abbreviations BIC brachium of the inferior colliculus - BSC brachium of the superior colliculus - C cerebellum - CG central grey - i interlaminar zone(s) of the dorsal lateral geniculate nucleus - IC inferior colliculus - ICc central nucleus of the inferior colliculus - LG dorsal lateral geniculate nucleus - m magnocellular layer(s) of the dorsal lateral geniculate nucleus - MG medial geniculate body - p parvocellular layer(s) of the dorsal lateral geniculate nucleus - P pulvinar complex - Pi inferior pulvinar - PG pregeniculate nucleus - Pl lateral pulvinar - Pm medial pulvinar - s superficial layer(s) of the dorsal lateral geniculate nucleus - SC superior colliculus - sgs stratum griseum superficiale of the superior colliculus - R reticular nucleus of the thalamus - VP ventroposterior group - 17 Area 17 Supported by NEI Grants EY-07007 (J. Graham) and EY-02686 (J.H. Kaas)     

Laminar origin of the tecto-thalamic projections in the albino rat

Cells of origin of the tecto-LP (lateroposterior nucleus of the thalamus) projection and the tecto-LGNd (dorsal nucleus of the lateral geniculate body) projection were studied in the albino rat by means of retrograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). Tecto-LGNd neurons with small spindle form were located in the stratum griseum superficiale of the superior colliculus (SC), whereas tecto-LP neurons with polygonal shape were found in the stratum opticum of the SC.     

Superficial tectal neurons projecting to the dorsolateral pontine nucleus in the rabbit

Summary After WGA-HRP injections in the pontine grey involving the dorsolateral pontine nucleus, a great number of labeled cells were found in the superficial layers of the ipsilateral superior colliculus. The majority of these cells were located in the stratum griseum superficiale (SGS). Few labeled cells were found in the stratum opticum, and the stratum zonale (SZ) showed no labeled cells. Labeled cells in the SGS formed a rather homogeneous population as most of them had fusiform somata with an upper dendritic process which runs vertically to reach the SZ. These cells were mainly located in the middle third of the SGS, forming a sublamina in this layer. These results demonstrate the participation of the superficial tectal layers in the ipsilateral descending pathway of the superior colliculus, allowing visual information to reach precerebellar stations at the dorsolateral pontine nucleus.     

Origins of the pretectal and tectal projections to the central lateral nucleus in the cat

The pretectal and tectal projections to the thalamic intralaminar nuclei in the cat were studied following horseradish peroxidase injections centered in the central lateral nucleus. Retrogradely labeled neurons were found in both the pretectum and the superior colliculus, ipsilateral and, to a lesser extent, controlateral to the injection site. Labeled pretectal neurons were found throughout all pretectal nuclei; the densest concentrations were in the medial pretectal nucleus, the anterior pretectal nucleus and the nucleus of the posterior commissure. The major source of tectal projections were the small neurons in the stratum griseum intermediate.     

Distribution of the tecto-thalamic projection neurons in the hereditary microphthalmic rat

Summary Tecto-thalamic projections in the hereditary bilaterally microphthalmic rat were studied by means of WGA-HRP injection into the dorsal lateral geniculate nucleus (LGNd) and the lateroposterior thalamic nucleus (LP). Histological study in the mutant rats showed that whereas LGNd and superficial layers of the superior colliculus (SC) suffered from a remarkable reduction in size, LP had no histological changes as compared to the normal animals. Unilateral injection of the tracer into the microphthalmic LGNd showed that WGA-HRP positive neurons were present mostly in the ipsilateral str. griseum superficiale (SGS) of the SC. However, the number of labeled SGS neurons of the microphthalmic animals was about 3% of the normal. Although cell bodies of the normal tecto-LGNd neurons in the SGS were spindle-form in shape and issued one or two proximal dendrites from each pole, the microphthalmic tecto-LGNd neurons showed an irregular contour and their dendrites were not so intensively labeled. Unilateral injections of WGA-HRP into the LP revealed that the tecto-LP neurons were mainly distributed in the ipsilateral str. opticum of the colliculus. (SO) in both normal and microphthalmic animals. However, the number of labeled SO cells in the microphthalmic rat was about one-half of the normal. Furthermore, the size of labeled tecto-LP neurons was smaller than that of the normal ones, and they showed irregular round to oval cell bodies with equivocally labeled dendrites, in contrast to the normal tecto-LP neurons with polygonal cell bodies extending three or more dendrites in a radial fashion. These results indicate that there exist the tecto-LGNd and -LP projection neurons in the microphthalmic rat and that their laminally segregated projection is fundamentally preserved. However, the number of the tecto-thalamic projection neurons, especially of the tecto-LGNd cells, was markedly diminished in the mutant tectum compared to normals.Abbreviations CST cortico-spinal tract - DRN dorsal raphe nucleus - DTN dorsal tegmental nucleus - LGNd pars dorsalis of the lateral geniculate nucleus - LLN nucleus of the lateral lemniscus - LM medial lemniscus - LP lateroposterior thalamic nucleus - MGN medial geniculate nucleus - MRF midbrain reticular formation - OT optic tract - P pretectal area - PAG periaqueductal gray - PB parabigeminal nucleus - PN pontine nuclei - PCS superior cerebellar peduncle - SGS superficial gray layer of the superior colliculus - SO stratum opticum of the superior colliculus - SN substantia nigra - Vm motor nucleus of the trigeminar nerve - Vs sensory nucleus of the trigeminar nerve     

Fiber connections of the periventricular pretectal nucleus in a teleost, tilapia (Oreochromis niloticus)

Fiber connections of the periventricular pretectal nucleus were studied by a tract-tracing method in a teleost, tilapia. After tracer injections into the periventricular pretectal nucleus, labeled neurons were observed ipsilaterally in the area pretectalis pars ventralis, area pretectalis pars dorsalis, optic tectum and ventrolateral nucleus of semicircular torus, bilaterally in the ventromedial thalamic nucleus, principal sensory trigeminal nucleus and descending trigeminal nucleus, and contralaterally in the periventricular pretectal nucleus and corpus cerebelli. Two types of tectal neurons were labeled in the stratum album centrale and the stratum periventriculare. The somata in the stratum album centrale were large and oval or multipolar. The somata in the stratum periventriculare were pyriform with an apical dendrite that ramified at the boundary zone between the stratum griseum centrale and stratum fibrosum et griseum superficiale. Anterogradely labeled terminals were present in the ipsilateral area pretectalis pars dorsalis, optic tectum and corpus cerebelli, the bilateral ventromedial thalamic nucleus, lateral valvular nucleus, oculomotor nucleus and inferior olive, and the contralateral periventricular pretectal nucleus. The present study suggests that the periventricular pretectal nucleus conveys somatosensory and mechanosensory lateral line inputs in addition to the visual information to the cerebellum.     

Contralateral corticofugal projections to cat visual thalamus

Summary Contralateral corticofugal projections from visual cortical areas to thalamic nuclei were demonstrated in the cat using anterograde transport of tritiated proline. Thalamic nuclei receiving projections from contralateral visual cortex include both subdivisions of the lateral-posterior nucleus, the posterior nucleus of Rioch, and the posterior nuclear complex.Abbreviations BIC brachium of the inferior colliculus - BN nucleus of the brachium of the inferior colliculus - BSC brachium of the superior colliculus - C dorsal lateral geniculate nucleus, C laminae - CG central gray matter - D nucleus of Darkschewitz - FR fasciculus retroflexus - FTC central tegmental field - H habenula - IPN interpeduncular nucleus - LGNd dorsal lateral geniculate nucleus, A laminae - LGNv ventral lateral geniculate nucleus - LP lateral posterior complex - LPi interjacent division of lateral posterior complex - LPl lateral division of lateral posterior complex - LPm medial division of lateral posterior complex - M mammillary body - MGM magnocellular division of medial geniculate nucleus - MGN medial geniculate nucleus - MGP parvocellular division of medial geniculate nucleus - MIN medial interlaminar division of lateral geniculate nucleus - MML medial medullary lamina - NOT nucleus of the optic tract - OT optic tract - P cerebral peduncle - PA anterior pretectal nucleus - PC nucleus of the posterior commissure - PM medial pretectal nucleus - PO posterior nuclear group - PoC posterior commissure - POi intermediate division of posterior nuclear complex - POL pretectal olivary nucleus - POm medial division of posterior nuclear complex - PPT posterior pretectal nucleus - PUL pulvinar - RN red nucleus - RNR posterior nucleus of Rioch - SG suprageniculate nucleus - SGI stratum griseum intermedium of superior colliculus - SGP stratum griseum profundum of superior colliculus - SCSl lower division of stratum griseum superficiale of superior colliculus - SGSu upper division of stratum griseum superficiale of superior colliculus - SN substantia nigra - SO stratum opticum of superior colliculus - TC tectal commissure - III III nerve - IIIN nucleus of III nerve     

Brain stem projections to the pulvinar-lateralis posterior complex of the cat

Summary The present experiments were undertaken to define the areas of projection of pretectum and superior colliculus to the pulvinar and n. lateralis posterior, respectively, and to define other brain stem structures projecting to these thalamic nuclei in cats. For this purpose the technique of retrograde transport of horseradish peroxidase (HRP) has been used.After injection of the enzyme in the pulvinar, neurons were labeled in all subdivisions of the pretectal area. The majority of the labeled cells were located in the n. pretectalis posterior and n. tractus opticus although cells filled with HRP were present also in the n. pretectalis anterior pars compacta and area pretectalis medialis. Neurons projecting to the pulvinar were also found in the periaqueductal gray, reticular formation and locus coeruleus.When HRP was injected in the n. lateralis posterior, labeled neurons were present in the II and III subdivisions of the second layer of the superior colliculus. The location of these cells shifted from medial to lateral as the injections were shifted from posterior to anterior within the lateralis posterior. Neurons projecting to this nucleus were also present in the intermediate layers of the superior colliculus, lateral hypothalamus and parabigeminal nucleus.The possible role of the pretectal area and superior colliculus in mediating somesthetic input to the pulvinar and lateralis posterior, respectively, and the role of these structures in the control of ocular movements, are discussed.Abbreviations APM area pretectalis medialis - Cu nucleus cuneiformis - CS nucleus centralis superior - fr fasciculus retroflexus - Gp pontine gray - Hb nucleus habenulae - IC inferior colliculus - LC locus coeruleus - LGB lateral geniculate body - LP lateralis posterior - MGB medial geniculate body - nPA_c nucleus pretectalis anterior pars compacta - nPA_r nucleus pretectalis anterior pars reticularis - nPC nucleus posterior commissurae - nPP nucleus pretectalis posterior - nTO nucleus tractus opticus - PAG periaqueductal gray - PB nucleus parabigeminalis - Pi pulvinar inferior - PO nucleus posterior of the thalamus - Pul pulvinar - Pt pretectum - RF reticular formation - Rtp tegmental reticular nucleus - SC superior colliculus Supported by H. de Jur Foundation and USPHS Grant TWO 2718Present address: Max-Planck-Institut für biophysikalische Chemie, Postfach 968, D-3400 Göttingen, Federal Republic of Germany     

Projections to the superior colliculus from the dorsal hypothalamic area and other prosencephalic structures derived from the embryonic subthalamic longitudinal band of the diencephalon

After injections of an aqueous solution of horseradish peroxidase (HRP) restricted to the superior colliculus of the cat, labeled neurons were found ipsilaterally in the dorsal hypothalamic area, lateral hypothalamus, zone incerta, reticular thalamic nucleus and ventral lateral geniculate. In most cases labeled neurons were observed in the same structures of the contralateral side. Some scattered neurons were observed in other hypothalamic structures and the globus pallidus. Most of these prosencephalic formations are subthalamic derivatives, thus having a common embryologic origin.     

Distribution of calbindin, parvalbumin and calretinin in the lateral geniculate nucleus and superior colliculus in Cebus apella monkeys

We studied the distribution of the calcium-binding proteins calbindin, parvalbumin and calretinin, in the superior colliculus and in the lateral geniculate nucleus of Cebus apella, a diurnal New World monkey. In the superior colliculus, these calcium-binding proteins show different distribution patterns throughout the layers. After reaction for calretinin one observes a heavy staining of the neuropil with few labeled cells in superficial layers, a greater number of large and medium-sized cells in the stratum griseum intermediale, and small neurons in deep layers. The reaction for calbindin revealed a strong staining of neuropil with a large number of small and well stained cells, mainly in the upper half of the stratum griseum superficiale. Intermediate layers were more weakly stained and depicted few neurons. There were few immunopositive cells and little neuropil staining in deep layers. The reaction for parvalbumin showed small and medium-sized neurons in the superficial layers, a predominance of large stellate cells in the stratum griseum intermediale, and medium-sized cells in the deep layers. In the lateral geniculate nucleus of Cebus, parvalbumin is found in the cells of both the P and M pathways, whereas calbindin is mainly found in the interlaminar and S layers, which are part of the third visual pathway. Calretinin was only found in cells located in layer S. This pattern is similar to that observed in Macaca, showing that these calcium-binding proteins reveal different components of the parallel visual pathways both in New and Old World monkeys.     

Specific projections of retina transplanted to rat brain

Summary Retinae were taken from fetal rats and transplanted adjacent to the superior colliculus of neonatal rats. After 1 month survival, the transplants were surgically removed from the hosts, locally damaged or injected with horseradish peroxidase (HRP) to determine the distribution of the transplant efferents in the host brains. Histological examination of the transplants revealed cell and plexiform layers characteristic of normal retinae. Since the retinae were undifferentiated at the time of transplantation, this layering developed within the host. The only obvious differences from normal retina were that the layers were organized in rosettes or folded sheets and lacked well developed photoreceptor outer segments. In animals which had lesions or HRP injections confined to the retinal transplant, proper staining of sections of the host brain revealed transplant projections. These projections were confined to the optic tract and nuclei which are normally retinorecipient such as the superior colliculus and dorsal lateral geniculate nucleus. Projections were found along the border of non-retinorecipient nuclei such as the lateral posterior nucleus, but did not appear to enter these nuclei. It was observed that within the superior colliculus the host retinal input had an effect on the distribution of the transplant projection. In one-eyed hosts the transplant projection was distributed throughout the stratum (s.) zonale, s. griseum superficiale, and s. opticum; whereas in the two-eyed hosts, the transplant projection was confined to the s. zonale and the border between s. griseum superficiale and s. opticum.We suggest that a special affinity exists between the axons of the retinal transplants and host visual structures. Furthermore, factors, such as competition and timing may be important in determining the distribution of the transplant axons within the specific target nuclei. Transplantation appears to be a useful technique for further studies on the mechanisms underlying the development of specific neuronal connections.     

Laminar origin of ipsilateral tectopontine pathways

The purpose of these experiments was to identify the cells of origin of the ipsilateral tectopontine pathways in the grey squirrel (Sciurus carolinensis). Following injections of tritiated amino acids into individual collicular laminae, labelled fibers could be traced to the dorsolateral pontine nuclei and overlying lateral pontine tegmentum. Fibers originating in stratum griseum superficiale terminated most heavily within the pontine nuclei whereas those arising from stratum griseum profundum terminated most heavily within the tegmentum. After horseradish peroxidase was injected into the dorsolateral pontine nuclei, cells labelled with reaction product were found in all 3 grey laminae of the superior colliculus, but the majority were located in stratum griseum superficiale. In contrast, when horseradish peroxidase was injected into the tectorecipient pontine tegmentum, most of the labelled cells were located in stratum griseum profundum.These results indicate that each of the 3 grey laminae of the superior colliculus projects to both the dorsolateral pontine nuclei and the lateral pontine tegmentum. However, the pathway to the pontine nuclei arises chiefly in stratum griseum superficiale while the tectotegmental pathway arises chiefly in stratum griseum profundum.     

Evidence for intrinsic expression of enkephalin-like immunoreactivity and opioid binding sites in cat superior colliculus

We have investigated the cellular localization of opioid peptides and binding sites in the cat's superior colliculus by testing the effects of retinal deafferentation and intracollicular excitotoxin lesions on patterns of enkephalin-like immunostaining and opiate receptor ligand binding. In normal cats, enkephalin-like immunoreactivity marks a thin tier in the most dorsal stratum griseum superficiale, small neurons of the stratum griseum superficiale, and patches of fibers in the intermediate and deeper gray layers. Eliminating crossed retinotectal afferents by contralateral eye enucleation had little immediate effect on this pattern, although chronic eye enucleation from birth did reduce immunoreactivity in the superficial layers. By contrast, fiber-sparing destruction of collicular neurons by the excitotoxins N-methyl-D-aspartate and ibotenic acid virtually eliminated enkephalin-like immunoreactivity in the neuropil of the upper stratum griseum superficiale, presumably by killing enkephalinergic cells of the superficial layers. Such lesions did not eliminate the patches of enkephalin-like immunoreactivity in the deeper layers. In normal cats, opiate receptor ligand binding is dense in the stratum griseum superficiale, particularly in its upper tier, and moderately dense in the intermediate gray layer. Contralateral eye removal had no detectable effect on the binding pattern, but excitotoxin lesions of the colliculus dramatically reduced binding in both superficial and deep layers. Some ligand binding, including part of that in the upper stratum griseum superficiale, apparently survived such lesions. Similar effects were observed in the lateral geniculate nucleus: enucleation produced no change in binding, whereas excitotoxin lesions greatly reduced specific opiate binding. We conclude that in the superficial collicular layers, both enkephalin-like opioid peptides and their membrane receptors are largely expressed by neurons of intrinsic collicular origin. The close correspondence between the location of these intrinsic opioid elements and the tier of retinal afferents terminating in the upper stratum griseum superficiale further suggests that opiatergic interneurons may modulate retinotectal transmission postsynaptically.     

Identification of geniculo-tectal relay neurons in the rat's ventral lateral geniculate nucleus

Summary In the rat's ventral lateral geniculate nucleus (vLGN), geniculo-tectal relay neurons (GTR-neurons) could be identified by the retrograde transport of horseradish peroxidase (HRP) after injection in the superior colliculus (SC). GTR-neurons correspond to class III cells described by Brauer and Schober (1973) in Golgi preparations of the rat's vLGN. The distribution of GTR-neurons is restricted to the lateral subnucleus of vLGN. According to Swanson et al. (1974), the axons of these cells terminate in lower Stratum griseum superficiale and in Stratum opticum, Stratum griseum intermedium and Stratum album intermedium of SC.The GTR-neurons are characterized by very thick and long proximal dendritic segments which have a smooth surface. Dendrites branch preponderantly in their distal regions and only in this part form many multiform protrusions. There is some evidence that retinal axons terminate on these dendritic surface structures. The supposed differences in the afferent patterns between GTR-neurons in the vLGN and geniculo-cortical relay neurons in the dorsal lateral geniculate nucleus are discussed.Sponsored by a grant of the Ministry of Science and Technology of the GDR     

The nigrotectal projection and tectospinal neurons in the rat. A light and electron microscopic study demonstrating a monosynaptic nigral input to identified tectospinal neurons

In order to investigate the nigro-tecto-spinal pathway in the rat, the pattern of termination of nigrotectal fibres and the distribution of tectospinal neurons have been investigated in a light and electron microscopic study of the superior colliculus. In addition, the pattern of termination of nigrotectal fibres was compared to the pattern of acetylcholinesterase staining. The light microscopic studies showed that the nigrotectal fibres, which had been identified by anterograde transport of horseradish peroxidase from the substantia nigra, terminated in a distinctive clustered pattern throughout the rostrocaudal extent of the stratum griseum intermedium, stratum album intermedium and adjacent dorsal portion of the stratum griseum profundum of the ipsilateral superior colliculus. The clusters of nigrotectal terminals formed a series of branching, interconnected longitudinal columns which largely corresponded with the pattern of acetylcholinesterase staining. The tectospinal neurons, which had been identified by retrograde transport of horseradish peroxidase from the spinal cord, had mainly large-sized somata, were stellate in shape with multiple long dendrites, and formed variable-sized clusters of 4-15 neurons within lateral regions of the ventral stratum album intermedium and dorsal stratum griseum profundum. In experiments where both the nigrotectal terminals and the tectospinal neurons were labelled by the transport of horseradish peroxidase, the clusters of tectospinal neurons largely corresponded with the regions of densest nigrotectal fibre termination in the lateral regions of the superior colliculus. In addition, a small contralateral nigrotectal projection was localized in the rostrolateral region of the superior colliculus where the crossed fibres terminated in a clustered pattern in alignment with clusters of tectospinal neurons in this region. Electron microscopic examination of the superior colliculus following ibotenic acid lesions in the substantia nigra and horseradish peroxidase injections in the spinal cord showed multiple degenerating nigrotectal boutons in synaptic contact with the soma and the mainstem and secondary dendrites of labelled tectospinal neurons in the lateral regions of the stratum album intermedium and stratum griseum profundum of the superior colliculus. The majority of the degenerating nigrotectal boutons showed electron-lucent degenerative changes and were in axodendritic contact. All of the identified nigrotectal synapses were of the symmetrical type.(ABSTRACT TRUNCATED AT 400 WORDS)     

Time of origin of neurons of the rat superior colliculus in relation to other components of the visual and visuomotor pathways

Summary Groups of pregnant rats were injected with two successive daily doses of ³H-thymidine from gestational day 12 and 13 (E12+E13) until the day before parturition (E21+22) in order to label all the multiplying precursors of neurons. At 60 days of age the proportion of neurons generated (or no longer labelled) on specific days was determined in the separate layers of the superior colliculus. Neurogenesis begins with the production of a few large multipolar neurons in layers V and IV on day E12; the bulk (87%) of these cells are generated on day E13. This early-produced band of large neurons, the intermediate magnocellular zone, divides the superior colliculus into two cytogenetically distinct regions. In both the deep and the superficial superior colliculus neuron production is relatively protracted. In the deep superior colliculus neuron production peaks on day E15 in layer VII, on day E15 and E16 in layer VI, and on day E16 (the large neurons excluded) in layer V, indicating an inside-out sequence. In the superficial superior colliculus peak production time of layer III cells is on day E15 and of layer IV cells on day E16; peak production time of both layer I and II is on day E16 but in the latter region neuron production is more prolonged and ends on day El8. One interpretation of these results is that the two pairs of superficial layers are produced in an outside-in sequence. These three cytogenetic subdivisions of the superior colliculus may be correlated with its structural-functional parcellation into an efferent spinotectal, a deep somatomotor and a superficial visual component.A comparison of neurogenesis in different components of the visuomotor and visual pathways of the rat indicates that the motor neurons of the extraocular muscles, the abducens, trochlear and oculomotor nuclei, and neurons of the nucleus of Darkschewitsch are produced first. Next in line are source neurons of efferents to the bulb and the spinal cord: those of the Edinger-Westphal nucleus and the intermediate magnocellular zone of the superior colliculus. These are followed by the relay neurons of the dorsal nucleus of the lateral geniculate body. The neurons of the superficial superior colliculus and of the visual cortex implicated in visual sensori-motor integrations are produced last.Abbreviations A aqueduct - ap stratum album profundum (layer VII) - bi brachium of the inferior colliculus - c caudal - CGd central gray, pars dorsalis - CGl central gray, pars lateralis - CGv central gray, pars ventralis - dm deep magnocellular zone - EW Edinger-Westphal nucleus - gi stratum griseum intermediale (layer IV) - gp stratum griseum profundum (layer VI) - gs stratum griseum superficiale (layer II) - IC inferior colliculus - im intermediate magnocellular zone - LGd lateral geniculate nucleus, pars dorsalis - ll lateral lemniscus - lm stratum lemnisci (layer V) - MG medial geniculate nucleus - ND nucleus of Darkschewitsch - NO nucleus of the optic tract - op stratum opticum (layer III) - ot optic tract - r rostral - SC superior colliculus - vIII third ventricle - ZO stratum zonale (layer I) - III oculomotor nucleus - IV trochlear nucleus - Vm mesencephalic nucleus of the trigeminal - VI abducens nucleus     

Electromyographic studies of neck muscles in the intact cat

Summary Substance P (SP)-, vasoactive intestinal polypeptide (VIP)-, and cholecystokinin (CCK)-like immunoreactive (LI) neurons were found in the superior colliculus (SC) of the rat, and examined to ascertain whether they sent projection fibers to the dorsal lateral geniculate nucleus (LGNd). Immunocytochemical staining with antisera against SP, VIP, and CCK showed that many immunoreactive neuronal cell bodies were located in the superficial layers of the SC, especially in the stratum griseum superficiale. The pattern of distribution of these immunoreactive neuronal cell bodies in the SC was similar to that of neuronal cell bodies which were retrogradely labeled with WGA-HRP (wheat germ agglutinin-horseradish peroxidase conjugate) injected ipsilaterally into the LGNd. On the other hand, SP-, VIP- and CCK-LI axons were seen most densely in the lateral part of the LGNd, especially in the small-celled LGNd zone adjacent to the optic tract, where anterograde labeling was also observed after injection of WGA-HRP ipsilaterally into the superficial layers of the SC. When a lesion was produced by kainic acid injection into the superficial layers of the SC, axons showing SP-, VIP-, or CCK-LI in the LGNd ipsilateral to the lesion were markedly depleted. The results indicate that SC-LGNd projection neurons contain SP, VIP, and/or CCK in the rat.     

Retinofugal projections in hedgehog-tenrecs (Echinops telfairi and Setifer setosus)

Summary Using the autoradiographic tracing technique the retinal projections were studied in the tenrecs, Echinops telfairi and Setifer setosus (insectivora, tenrecidae). Bilateral projections were found to the n. suprachiasmaticus, the anterior hypothalamic area, the dorsal and ventral lateral geniculate bodies, the pretectal olivary nucleus and the superior colliculus. The contralateral projections were usually more intense than the ipsilateral ones except the retinohypothalamic connections. A partial segregation of the projection fields from both eyes was present in the dorsal and ventral lateral geniculate bodies. In the superior colliculus retinal fibers predominantly involved the stratum zonale and the upper portion of the stratum griseum superficiale on both sides. The projections to the deeper portion of the colliculi were rather faint, particularly on the ipsilateral side. Target areas receiving contralateral projections exclusively were the periamygdaloid area (labeled only in Setifer), the terminal accessory nuclei including the n. tractus optici and the inferior colliculus. The data are compared with other species. The most striking finding may concern the projection to the medial terminal nucleus being quite prominent in marsupials and most eutherian mammals (including the erinaceomorphous hedgehogs), but greatly reduced in tenrecs and primates.Abbreviations ae commissura anterior - AmP periamygdaloid area - Col colliculus inferior - CoS colliculus superior - cp cerebral peduncule - Ec Echinops telfairi/lesser hedghog-tenrec - GLD corpus geniculatum laterale, pars dorsalis - GLV corpus geniculatum laterale, pars ventralis - GLVa-d subdivisions of GLV - GM corpus geniculatum mediale - HbM n. habenulae medialis - HyA anterior hypothalamic area - oc chiasma opticum - on nervus opticus - ot tractus opticus - PT pretectum - PTO n. olivarius praetectalis - Ru n. ruber - SCh n. suprachiasmaticus - Se Setifer setosus/greater liedgehog-tenrec - SGI stratum griseum intermedium - SPG stratum griseum profundum - SGS stratum griseum superficiale - SO stratum zonale - To n. motorius nervi trochlearis - TmD n. terminalis dorsalis - TmL n. terminalis lateralis - TmM n. terminalis medialis - TrO n. tractus optici     

Tectal neurons projecting to the isthmo-optic nucleus in the Japanese quail

Horseradish peroxidase (HRP) injected into the isthmo-optic nucleus (ION) of the Japanese quail retrogradely labeled neurons in the ipsilateral optic tectum. Some of these neurons exhibited a characteristic 'willow-like' appearance. Somata of these neurons were round or pyriform, usually located in lamina h of the stratum griseum et fibrosum superficiale (SGFS), and emitted several thin dendritic branches that ramified in the deeper laminae of SGFS but not in the retinal recipient laminae of SGFS. Their axons had horizontal processes ramifying in the deepest lamina of SGFS or the stratum griseum centrale.