Electrophysiological relations between the superior colliculus and the red nucleus in the cat.

The electrical activity of single units located in the parvicellular part of the red nucleus (pRP) was recorded extracellularly in nitrous oxide anesthetized and C1-transected adult cats. In this area, neurons were found to respond to electrical stimulation applied to intermediate and deep layers of the right superior colliculus (SC). Forty neurons located in the pRN of both sides were studied. Three neurons out of 18 (16.6%) located in the contralateral pRN and six neurons out of 22 (27.3%) located in the ipsilateral pRN were driven by the right SC stimulation. The pRN neurons were separated into four groups according to the latency response to the SC stimulation: 1) 0.6-1.9 ms, 2) 2-4 ms, 3) 4-6 ms, 4) variable latency responses. Each of these four groups of neurons showed a particular pattern of discharge, even though their discharge frequency showed a strong consistency. Four pRN neurons, which responded to SC stimulation, showed a significant correlation with spontaneous horizontal eye movements of saccadic type. It is known that the SC represents one of the main outputs of the striato-nigral motor system. The relation between the SC and the pRN described in the present study suggest that connections exist between the cortico-rubral and the striato-nigral systems, since both have the SC as a common output structure. It is likely, therefore, that the cortico-rubral-SC system is involved in the control of oculomotor functions, and that the SC may serve to establish interactions between systems concerned with eye movements.     

Morphological correlates of pyramidal cell adaptation rate in the electrosensory lateral line lobe of weakly electric fish

1. Extracellular HRP injections into the nucleus praeeminentialis dorsalis (NPd) of Apteronotus leptorhynchus retrogradely labeled a population of electrosensory lateral line lobe (ELL) efferent cells, deep basilar pyramidal cells, that differ morphologically from the previously described basilar and nonbasilar pyramidal cells. These neurons are found deep in the ELL cellular layers; they have small cell bodies and very short sparsely branching apical dendritic trees. The previously described basilar and nonbasilar pyramidal cells are larger, have extensive apical dendrites and are found more superficially. 2. Axon terminals of the deep basilar pyramidal cells were recorded from in the NPd and labeled with lucifer yellow. These NPd afferents have high, regular spontaneous firing rates, and respond tonically to changes in electric organ discharge amplitude. 3. Deep basilar pyramidal cell bodies were recorded from and labeled in the ELL, and these showed the same physiological responses as did the NPd afferent fibers. 4. In addition, basilar pyramidal cells were found which had spontaneous activity patterns and adaptation characteristics intermediate to those typical of the superficial basilar pyramidal cells and the deep basilar pyramidal cells. The size of the pyramidal cells' apical dendritic trees and the placement of their somata within the dorsoventral extent of the ELL cellular layers are highly correlated with the neurons' physiological properties.     

Morphology of calretinin-immunoreactive neurons in the superficial layers of hamster superior colliculus after enucleation: lack of co-localization with GABA

We recently reported on the distribution and effects of eye enucleation on the immunoreactivity of calretinin in the superficial layers of the hamster superior colliculus (SC). In the present study, we describe the types of labeled cells and compare this labeling to that of GABA, the major inhibitory neurotransmitter in the central nervous system. An almost complete depletion of calretinin-immunoreactive (IR) fibers in the superficial layers of the contralateral SC was found following unilateral enucleation. On the contralateral SC, many calretinin-IR cells were newly appeared. The majority of the newly-appeared cells had small- to medium-sized round, oval, or vertical fusiform cell bodies. Two-color immunofluorescence revealed that none of these newly-appeared cells were labeled with an antibody to GABA. The present results show that the calretinin-IR cells are unique in the superficial hamster SC when compared to most of the other brain areas, where many calretinin-IR cells are GABAergic interneurons.     

Projections from cortical visual areas of the superior temporal sulcus to the superior colliculus, in macaque monkeys.

1. The distribution of tectal projections of two visual areas of the superior temporal sulcus (MT and MST areas) has been studied, in five Macaca fascicularis, by means of the autoradiographic method tracing the anterograde transport of tritiated aminoacids intracortically injected. 2. In all cases the ipsilateral superior colliculi (SC) were found labelled, whereas the contralateral ones were devoid of label. 3. The three brains injected in the MT area resulted in SC labels that involved the superficial gray layer (SGS), the stratum opticum (SO) and the intermediate gray layer (SGI), sparing the layers below SGI. 4. The collicular labels found after injections within the MST area exhibited their distribution over the deep SC subdivision, whereas they spared all the superficial layers but the deep part of the SO. 5. In two animals with large uptake zones, one in MT and the other in MST, the labelling within the SGI showed a cluster-like pattern. 6. The distinct found bulk of projections of MT and MST respectively to the superficial and deep subdivisions of the SC, along with a number of peculiar connections of the MST area as mentioned in the text, contribute to depict an overall neural network in which MST appears to be more strongly involved than MT in linking sensory visual with oculomotor attentive functions.     

Par6b Regulates the Dynamics of Apicobasal Polarity during Development of the Stratified Xenopus Epidermis

During early vertebrate development, epithelial cells establish and maintain apicobasal polarity, failure of which can cause developmental defects or cancer metastasis. This process has been mostly studied in simple epithelia that have only one layer of cells, but is poorly understood in stratified epithelia. In this paper we address the role of the polarity protein Partitioning defective-6 homolog beta (Par6b) in the developing stratified epidermis of Xenopus laevis. At the blastula stage, animal blastomeres divide perpendicularly to the apicobasal axis to generate partially polarized superficial cells and non-polarized deep cells. Both cell populations modify their apicobasal polarity during the gastrula stage, before differentiating into the superficial and deep layers of epidermis. Early differentiation of the epidermis is normal in Par6b-depleted embryos; however, epidermal cells dissociate and detach from embryos at the tailbud stage. Par6b-depleted epidermal cells exhibit a significant reduction in basolaterally localized E-cadherin. Examination of the apical marker Crumbs homolog 3 (Crb3) and the basolateral marker Lethal giant larvae 2 (Lgl2) after Par6b depletion reveals that Par6b cell-autonomously regulates the dynamics of apicobasal polarity in both superficial and deep epidermal layers. Par6b is required to maintain the “basolateral” state in both epidermal layers, which explains the reduction of basolateral adhesion complexes and epidermal cells shedding.     

The formation of a neo-intima in textile prostheses implanted in the aorta of rats and dogs

Summary The formation of a neo-intima in textile prostheses implanted in the rat and dog aorta was studied by means of light- and scanning electron microscopy. Two independent cellular layers (the superficial and deep ingrowth layers) developed on the free surface and under the fibrin layer initially deposited on the inner surface of the prostheses. The superficial ingrowth layer invades the prosthesis from both the proximal and distal aortic stumps and extends over the primary fibrin layer, or replaces it. This layer consists mainly of smooth muscle cells of the triangular aortic type covered by endothelial-like cells. The deep ingrowth layer originates from cellular elements of the prosthetic bed. Fibroblasts, myofibroblasts and spindle-shaped smooth muscle cells invade the fibrin layer through the interstices of the fabric structure of the prosthesis. Precursors of endothelial cells, however, are absent from this population. The superficial and the deep ingrowth layers may become joined by progressive replacement of the fibrin layer, but remain distinguishable because of their different cellular components.When a continuous cellular layer is established on the inner surface of the prosthesis, and this is then covered by endothelial-like cells, the neo-intima formed remains stable during long-term studies.     

A new visual area on the inferior wall of the cat cruciate sulcus

Properties of 187 neurons in the inferior wall of the cruciate sulcus, in an area where electrical stimulation evoked unidirectional saccadic eye movements, were investigated in waking cats. Of the total number 172 responded to visual stimulation. Neurons in the surface layers of the cortex responded to simple visual stimuli: light or dark spots or bars, both stationary and moving at speeds of around 30 deg/sec. These neurons showed no selectivity as regards stimulus orientation but sometimes behaved selectively toward the direction of their movements. In the intermediate layers the maximal neuronal response was obtained to a model of a bird flaping its wings. Neuronal responses in the depth of the cortex were characterized by selectivity to movement of stimuli toward or away from the animal in a certain part of the visual field, irrespective of whether a light stimulus was presented against a dark background or a dark stimulus against the light background. Responses to visual stimulation were exhibited only if the animal was in a state of activation, when the EEG showed desynchronization, and they were absent in a state of quite wakefulness. No responses were obtained to auditory or somatic stimulation. Responses to visual stimulation were not found in neurons of the medial wall of the brain beneath the cruciate sulcus, but responses were recorded to eye movements of definite size or orientation. It is postulated that at least two contiguous retinotopically organized zones exist in this part of the brain. Activity of one of them is connected with visual function, that of the other with eye movements.Institute for Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 16, No. 6, pp. 766–773, November–December, 1984.     

Ultrastructural study of the in vitro interaction between Biomphalaria glabrata hemocytes and Schistosoma mansoni miracidia

Biomphalaria glabrata and Schistosoma mansoni relationship was studied by light microscopy (LM) and freeze-fracture replica technique (FFR). We observed very thin cytoplasmic extensions of hemocytes in the LM, which then surround immobilize the miracidia. FFR images showed that the contact site between hemocytes cytoplasmic extensions and the external tegumentary coat involved only superficial layers of miracidia. Numerous vacuoles and filopodia were observed in the hemocyte cytoplasm, the latter binding with those from neighboring cells. In spite of the close interfilopodia contact, no cellular junctions were seen at these sites nor between filopodia-miracidia contact areas. The observed migration of hemocytes and their disposition in layers surrounding the miracidia in vitro correspond to previous studies.     

Mucosubstance histochemistry of Brunner's glands, pyloric glands and duodenal goblet cells in the ferret

The mucosubstance of Brunner's glands, pyloric glands and duodenal goblet cells were studied using the various histochemical methods. The secretions of both Brunner's and pyloric glands were similar in their histochemical reactions. They contained neutral mucosubstances as in these glands in man. The duodenal goblet cells showed variations in their histochemical characters. (i) The secretions of most of the deep cells and the majority of superficial cells contained sialidase-labile and sialidase-resistant sialomucins. (ii) There were a few superficial and occasional deep cells, the secretions of which contained sulphated mucosubstances. (iii) There were some goblet cells, more in the villi than in the crypts, the secretions of which contained a mixture of sialomucins and a sulphated mucin. The sialomucin was mostly sialidase-labile and partly sialidase-resistant.     

Urodeles remove mesoderm from the superficial layer by subduction through a bilateral primitive streak

Urodeles begin gastrulation with much of their presumptive mesoderm in the superficial cell layer, all of which must move into the deep layers during development. We studied the morphogenesis of superficial mesoderm in the urodeles Ambystoma maculatum, Ambystoma mexicanum, and Taricha granulosa. In all three species, somitic, lateral, and ventral mesoderm move into the deep layer during gastrulation, ingressing through a "bilateral primitive streak" just inside the blastopore. The mesodermal epithelium appears to slide under the endodermal epithelium by a mechanism we term "subduction." Subduction removes the large expanse of superficial presumptive somitic and lateral-ventral mesoderm that initially separates the sub-blastoporal endoderm from the notochord, leaving the endoderm bounding the still epithelial notochord along the gastrocoel roof. Subduction may be a common feature of urodele gastrulation, differing in this regard from anurans. Subducting cells constrict their apices and become bottle-shaped as they approach the junction of the mesodermal and endodermal epithelia. Subducting bottle cells endocytose apical membrane and withdraw the tight junctional component cingulin from the contracting circumferential tight junctions. Either in conjunction with or immediately after subducting, the mesodermal cells undergo an epithelial-to-mesenchymal transition. The mechanism by which epithelial cells release their apical junctions to become mesenchymal, without disrupting the integrity of the epithelium, remains mysterious, but this system should prove useful in understanding this process in a developmental context.     

Light microscopy of the medial wall of the cerebral cortex of the lizard Psammodromus algirus

The telencephalic medial wall of the lizard Psammodromus algirus was studied using Golgi and conventional light microscopic techniques. The area is formed by two different cytological fields—medial cortex and dorsomedial cortex. These two cortices possess three layers dorsoventrally: a superficial plexiform layer, a cellular layer, and a deep plexiform layer. The alveus, a deep fiber system, runs adjacent to the ependyma. Four classes of neurons are found in the cellular layer of the medial cortex on the basis of soma shape, dendritic pattern, and position in the layer: horizontal, double pyramidal, and candelabra cells. Solitary cells are present in the superficial and deep plexiform layers of the medial cortex. Those of the superficial plexiform layer are stellate cells. Horizontal and vertical cells are found in the deep plexiform layer. Double pyramidal cells are the most frequently impregnated in the cellular layer of the dorsomedial cortex. In addition, candelabra cells are present at the lateral end of the layer. Two cell types are found in the deep plexiform layer of the dorsomedial cortex: solitary pyramidal cells and, among the fibers of the alveus, horizontal cells. Ependymal tanycytes line the ventricular surface, and protoplasmic astrocytes are found in the plexiform layers of both medial and dorsomedial cortices.     

Surgical anatomy and blood supply of the fascial layers of the temporal region

In 15 fresh cadavers (30 sides), we studied the two layers of fascia in the temporal region, with particular regard to their blood supply and to their usefulness--together or separately--as microvascular free-tissue autografts. The superficial temporal fascia (temporoparietal fascia, epicranial aponeurosis) lies immediately deep to the hair follicles. It is part of the subcutaneous musculoaponeurotic system and is continuous in all directions with other structures belonging to that layer--including the galea above and the SMAS layer of the face below. The deep temporal fascia (temporalis fascia, investing fascia of temporalis) is separated from the superficial fascia by an avascular plane of loose areolar tissue. It completely invests the superficial aspect of the temporalis muscle down to (but not beyond) the zygomatic arch. It is firmly attached to periosteum all around the margin of the muscles. Below it is attached to the upper border of the zygomatic arch. We found the deep temporal fascia to be supplied solely by the middle temporal artery, a constant branch of the superficial temporal. The middle temporal artery arises 1 to 3 cm below the upper border of the zygomatic arch, runs always superficial to the arch, and enters the deep temporal fascia immediately above that layer's attachment to the zygomatic arch. If the middle temporal vessels are protected, the two layers of temporal fascia can be raised together as a fully vascularized tissue island. This island can be fashioned as a bilobed or a double-layered flap, depending on the manner of dissection. The potential surgical usefulness of these findings is discussed.     

Mucosubstance histochemistry of Brunner's glands,pyloric glands and duodenal goblet cells in the ferret

Summary The mucosubstance of Brunner's glands, pyloric glands and duodenal goblet cells were studied using the various histochemical methods.The secretions of both Brunner's and pyloric glands were similar in their histochemical reactions. They contained neutral mucosubstances as in these glands in man.The duodenal goblet cells showed variations in their histochemical characters. (i) The secretions of most of the deep cells and the majority of superficial cells contained sialidase-labile and sialidase-resistant sialomucins. (ii) There were a few superficial and occasional deep cells, the secretions of which contained sulphated mucosubstances. (iii) There were some goblet cells, more in the villi than in the crypts, the secretions of which contained a mixture of sialomycins and a sulphated mucin. The sialomucin was mostly sialidase-labile and partly sialidase-resistant.     

Changes in cells's secretory organelles and extracellular matrix during endochondral ossification in the mandibular condyle of the growing rat

The mandibular condyle from 20-day-old rats was examined in the electron microscope with particular attention to intracellular secretory granules and extracellular matrix. Moreover, type II collagen was localized by an immunoperoxidase method. The condyle has been divided into five layers: (1) the most superficial, articular layer, (2) polymorphic cell layer, (3) flattened cell layer, (4) upper hypertrophic, and (5) lower hypertrophic cell layers. In the articular layer, the cells seldom divide, but in the polymorphic layer and upper part of the flattened cell layer, mitosis gives rise to new cells. In these layers, cells produce two types of secretory granules, usually in distinct stacks of the Golgi apparatus; type a, cylindrical granules, in which 300-nm-long threads are packed in bundles which appear "lucent" after formaldehyde fixation; and type b, spherical granules loaded with short, dotted filaments. The matrix is composed of thick banded "lucent" fibrils in a loose feltwork of short, dotted filaments. The cells arising from mitosis undergo endochondral differentiation, which begins in the lower part of the flattened cell layer and is completed in the upper hypertrophic cell layer; it is followed by gradual cell degeneration in the lower hypertrophic cell layer. The cells produce two main types of secretory granules: type b as above; and type c, ovoid granules containing 300-nm-long threads associated with short, dotted filaments. A possibly different secretory granule, type d, dense and cigar-shaped, is also produced. The matrix is composed of thin banded fibrils in a dense feltwork. In the matrix of the superficial layers, the "lucency" of the fibrils indicated that they were composed of collagen I, whereas the "lucency" of the cylindrical secretory granules suggested that they transported collagen I precursors to the matrix. Moreover, the use of ruthenium red indicated that the feltwork was composed of proteoglycan; the dotted filaments packed in spherical granules were similar to, and presumably the source of, the matrix feltwork. The superficial layers did not contain collagen II and were collectively referred to as perichondrium. In the deep layers, the ovoid secretory granules displayed collagen II antigenicity and were likely to transport precursors of this collagen to the matrix, where it appeared in the thin banded fibrils. That these granules also carried proteoglycan to the matrix was suggested by their content of short dotted filaments. Thus the deep layers contained collagen II and proteoglycan as in cartilage; they were collectively referred to as the hyaline cartilage region.     

The relationship of the superficial and deep facial fascias: relevance to rhytidectomy and aging.

Controversy persists regarding the relationship of the superficial facial fascia (SMAS) to the mimetic muscles, deep facial fascia, and underlying facial nerve branches. Using fresh cadaver dissection, and supplemented by several hundred intraoperative dissections, we studied facial soft-tissue anatomy. The facial soft-tissue architecture can be described as being arranged in a series of concentric layers: skin, subcutaneous fat, superficial fascia, mimetic muscle, deep facial fascia (parotidomasseteric fascia), and the plane containing the facial nerve, parotid duct, and buccal fat pad. The anatomic relationships existing within the facial soft-tissue layers are (1) the superficial facial fascia invests the superficially situated mimetic muscles (platysma, orbicularis oculi, and zygomaticus major and minor); (2) the deep facial fascia represents a continuation of the deep cervical fascia cephalad into the face, the importance of which lies in the fact that the facial nerve branches within the cheek lie deep to this deep fascial layer; and (3) two types of relationships exist between the superficial and deep facial fascias: In some regions of the face, these fascial planes are separated by an areolar plane, and in other regions of the face, the superficial and deep fascia are intimately adherent to one another through a series of dense fibrous attachments. The layers of the facial soft tissue are supported in normal anatomic position by a series of retaining ligaments that run from deep, fixed facial structures to the overlying dermis. Two types of retaining ligaments are noted as defined by their origin, either from bone or from other fixed structures within the face.(ABSTRACT TRUNCATED AT 250 WORDS)     

Distribution of neuropeptide Y immunoreactivity in human visual cortex and underlying white matter

Immunocytochemical techniques have been used to study neuropeptide Y (NPY) distribution in the human visual cortex (Brodman's areas 17, 18 and 19) NYP cell bodies belong mostly to inhibitory (multipolar and bitufted) but also to excitatory (bipolar and some pyramidal) neuronal types. Their distribution is similar in the three cortical areas studied: 20 to 40% of the NPY perikarya are located in the cortical gray matter, mostly in the deep layers, while the remaining 60 to 80% are located in the underlying white matter. Immunoreactive NPY processes form a rich network of intersecting fibers throughout the entire visual cortex. A superficial plexus (layers I and II) and a deep plexus (deep layer V and layer VI) of NPY fibers are present in areas 17, 18 and 19. In area 17, an additional well developed plexus is present in layers IVb and IVc. These plexuses receive branches from long parallel fibers arising from deep cortical layers or underlying white matter and terminating in superficial layers. Local or extrinsic NPY terminals wind around vessels in the cortex as well as in the white matter, and either penetrate them or form clusters of club endings on their walls. Our results suggest a role for NPY in human visual circuitry and in cortical blood flow regulation.     

神经毒素ECMA对家鸽视网膜神经节单元反应特性的影响

从家鸽视差表层总共记录了１０１个视网膜神经节单元,并定量分析研究ＥＣＭＡ损伤对其反应特性的影响,在对照组中,神经节单元都没有自发放电,而需要视觉刺激才能引起反应,对闪光刺激的反应,分别为ＯＮ—ＯＦＦ,ＯＮ,ＯＦＦ三种,其反应均是瞬变的,而且也都对在感受野内运动的小条纹起反应。４２个单元中有１４个是方向选择性单元。其它的则为运动敏感单元。方向选择性单元的无效方向不是均等分布的,其中有８个单元的无效是从前向后的,但没有发现其无效方向是从后向前的单元。与对照组相比,经ＥＣＭＡ损伤后的实验组中只记录到ＯＮ－ＯＦＦ反应和ＯＮ反应单元,未能找到单独的ＯＦＦ反应单元。神经节单元的ＯＮ反应部分为持续成分。所有的单元对运动条纹刺激都失掉了方向选择性,这些现象的机理可能是由于ＥＣＭＡ去除了胆碱能无足细胞所致。     

Effects of the thalamus on the development of cerebral cortical efferents in vitro

The cerebral cortex is a multilayered tissue, with each layer differing in its cellular composition and connections. Axons from deep layer neurons project subcortically, many to the thalamus, whereas superficial layer neurons target other cortical areas. The mechanisms that regulate the development of this pattern of connections are not fully understood. Our experiments examined the potential of the thalamus to attract and/or select neurites from appropriate cortical layers. First, we cocultured murine cortical slices in close proximity to thalamic explants in collagen gels. The amount of neurite outgrowth from deep layer cells was enhanced by, but not attracted to, the thalamic explants. Second, we cocultured cortical slices in contact with thalamic or cortical explants to test for laminar specificity of connections. Specificity was apparent after culture for about a week, in that deep cortical layers contained the highest proportions of corticothalamic cells and superficial cortical layers contained the highest proportions of corticocortical cells. After shorter culture of only a few days, however, specificity was not apparent and there were larger numbers of corticothalamic projections from the superficial layers than after a week. To study how the early nonspecific pattern of corticothalamic connections was transformed into the more specific pattern, we labeled corticothalamic cells early, after 2 days, but let the cultures survive for 8 days. On day 8, the nonspecific pattern of early-labeled cells was still seen. We conclude that although the thalamus does not block the initial entry of inappropriate axons from the superficial layers, many of these axons are subsequently lost. This suggests that contact-mediated interactions between cortical axons and the thalamus allow cortical efferents from appropriate layers to be distinguished from those arising in inappropriate layers. This may contribute to the development of layer-specific cortical connections in vivo.