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Biomedical subjects

H J Karten

Publications and source records attributed to H J Karten.

At least 109 records · Page 6Linked to original sources
PubMed1981

Immunocytochemical localization of vasoactive intestinal polypeptide-containing cells and processes in the suprachiasmatic nucleus of the rat: light and electron microscopic analysis.

The distribution of vasoactive intestinal polypeptide-like (VIP) immunoreactivity in neurons and processes within the suprachiasmatic nuclei (SCN) of the rat was investigated with light and electron microscopic immunocytochemical techniques. These studies utilized well characterized antisera directed to synthetic vasoactive intestinal polypeptide. Specificity was established by absorption of the antisera with synthetic vasoactive intestinal polypeptide. Neurons and dendrites exhibiting specific VIP immunoreactivity are concentrated in the ventral half of the nucleus, with the greatest concentration of immunoreactive perikarya occurring in the ventral SCN immediately adjacent to and within the optic chiasm (OC). Thin varicose axons containing VIP immunoreactivity are present throughout the SCN. A large number of immunoreactive axons leave the dorsal aspect of the SCN to reach the periventricular hypothalamic nucleus and continue dorsally to form an extensive plexus along the ventral border of the paraventricular hypothalamic nucleus. Other immunoreactive axons project upon the contralateral SCN via the OC. Ultrastructurally, VIP-containing neurons in the SCN are characterized by a spherical to slightly elongated soma and an invaginated nucleus that fills the majority of the cell body. In the soma, peroxidase reaction product is localized on the outer membrane of all cellular organelles. The reaction product of immunoreactive boutons is related primarily to vesicles, and some of these boutons establish axodendritic synaptic contacts in the SCN. The demonstration of VIP-containing neurons in the SCN provides further evidence that this nucleus is composed of a heterogeneous population of neurons which form distinct subfields within it.

Animals↗
PubMed1980

Substance P in the vagal sensory ganglia: localization in cell bodies and pericellular arborizations.

The distribution of Substance P-like immunoreactivity in the jugular and nodose ganglia of rabbits and pigeons has been studied using immunocytochemical staining techniques. Substance P-like immunoreactivity is localized to neuronal cell bodies and processes in the jugular and nodose ganglia, and to pericellular fiber plexi in the nodose ganglia of both species. The numbers and sizes of cells which exhibited Substance P-like immunoreactivity in each ganglion were determined using quantitative morphometric techniques. The distribution of Substance P-like immunoreactivity in the rabbit and pigeon vagal sensory ganglia is characterized by several general features. In most of the ganglia, immunoreactive neurons factor into discrete types which can be distinguished from one another, and from non-immunoreactive neurons, by size. In addition, immunoreactive nodose and jugular ganglion cells, respectively, are distinguishable on the basis of size. Finally, a considerably high percentage of immunoreactive neurons is found in the jugular ganglion than in the nodose ganglion. Substance P-like immunoreactivity was also seen in pericellular fiber plexi which encircle individual neurons in the nodose ganglion of rabbits and pigeons. These plexi are composed of varicose fibers which appear to terminate as boutons on the surface of the cells which they encircle. The distribution of Substance P-like immunoreactivity within the vagal sensory ganglia is discussed with respect to the possible peripheral targets and functions of Substance P-containing vagal afferents. Our findings suggest that Substance P-containing vagal sensory neurons are involved in a variety of visceral and somatic afferent functions.

Animals↗
PubMed1980

Basal ganglionic pathways to the tectum: studies in reptiles.

Relations between the basal ganglia and the tectum were investigated in two different orders of reptiles: turtles (Chrysemys scripta) and crocodilians (Caiman crocodilus). In both species, efferents from the paleostriatal complex, a telencephalic region considered comparable to the mammalian basal ganglia on the basis of topographic, histochemical, and hodological criteria, were found to project to a prominent pretectal cell group called the dorsal nucleus of the posterior commissure (nDCP). Cells within nDCP, in turn, were found to project extensively upon the optic tectum. This paleostriatal-pretectal-tectal pathway is comparable to a previously described paleostriatal-pretectal-tectal channel in birds that involves a relay in the pretectal nucleus, spiriformis lateralis (SpL). Neither the presently described paleostriatal-pretectal-tectal channel of reptiles nor that previously described in birds, however, appears comparable to the superficially similar basal ganglionic-nigral-superior collicular pathway of mammals. Rather, data from the present experiments indicate the existence of a second paleostriatal channel to the tectum, one which does appear comparable to the basal ganglionic-nigral-superior collicular pathway of mammals. This second paleostriatal channel to the tectum, relayed via a tegmental cell group termed the substantia nigra in turtles and the tegmentipedunculopontine complex in caiman, is of much lesser prominence in reptiles than the paleostriatal-pretectal-tectal channel. The present results indicate the existence of at least two separate systems by which the basal ganglia in reptiles can influence the midbrain roof. These two channels, particularly the prominent paleostriatal-pretectal-tectal pathway, may represent major routes by which the basal ganglia influence motor functions in reptiles. Further, although previous research had only indicated the existence of a paleostriatal-pretectal-tectal pathway in birds and a basal ganglionic-nigral-collicular channel in mammals, existing data are consistent with the hypothesis that both presently described pathways in reptiles exist in birds and mammals, though only one of the two may be prominent in mammals.

Alligators and Crocodiles↗
PubMed1980

Projections of the nucleus of the basal optic root in the pigeon: an autoradiographic and horseradish peroxidase study.

The efferent projections of the nBOR complex, have been studied with both anterograde autoradiographic and retrograde horseradish peroxidase (HRP) techniques. The nBOR complex includes three distinct subdivisions: the nucleus of the basal optic root (nBOR), the nBOR pars dorsalis (nBORd) and the nBOR pars lateralis (nBOR1). Unilateral injections of 3H-leucine or 3H-proline/3H-leucine mixtures into the nBOR complex have demonstrated prominent bilateral projections upon (1) the vestibulocerebellum, (2) the inferior olivary complex, (3) the oculomotor nuclear complex, (4) the nucleus interstitialis, contralateral projections upon (5) the contralateral nBOR complex and ipsilateral projections upon (6) a pretectal nucleus, the nucleus lentiformis mesencephali, pars magnocellularis. Unilateral injections of HRP confined to folia IXc,d and paraflocculus of the cerebellum, the contralateral nBOR complex or the nucleus lentiformis mesencephali resulted in retrograde labeling of predominantly medium and large size cells within the entire nBOR complex. Unilateral injections of HRP within the inferior olive resulted in retrograde labeling of small, spindle-shaped cells within nBOR and nBORd. Unilateral injections of the oculomotor complex which included the trochlear nucleus resulted in retrograde labeling of small cells within the ipsilateral nBORd and predominantly medium and large cells in the contralateral nBOR. The displaced ganglion cells of the retina give rise to a prominent and distinct projection upon the nBOR complex (Karten et al., '77). The nBOR complex in turn projects upon the oculomotor nuclear complex, the nucleus interstitialis and the vestibulocerebellum, regions which have been implicated in oculomotor function. These findings strongly suggest that the displaced ganglion cells and the accessory optic system have a major influence upon oculomotor reflexes including eye and head movements.

Animals↗
PubMed1980

Localisation of substance P immunoreactivity in amacrine cells of the retina.

Since its actions on smooth muscle were first described by von Euler and Gaddum, substance P has been isolated and characterised as an undecapeptide. The distribution of substance P-like immunoreactivity in both the central and peripheral nervous systems and its reported excitatory action on neurones implicate substance P as a possible neurotransmitter and/or neuromodulator. Previous studies using bioassay and radioimmunoassay techniques have reported substance P in retinal extracts. Here we describe the specific immunohistochemical localisation of substance P-like immunoreactivity in a population of morphologically distinct amacrine cells of the pigeon retina. The localisation of substance P-like immunoreactivity and the recent localisation of enkephalin-like and somatostatin-like immunoreactivity in other types of amacrine cells suggest that the neuropeptides have a specific role in retinal function.

Animals↗
PubMed1979

Origin, course and terminations of the rubrospinal tract in the pigeon (Columba livia).

The red nucleus and its spinal projections in the pigeon (Columba livia) have been studied using both normal and experimental material. The cytoarchitecture of the nucleus is described on the basis of Nissl-stained sections and reveals an organization generally similar to that of mammals. The large neurons (40-50 mum) tend to be located dorsomedially and ventrolaterally at more caudal nuclear levels, while the small- and medium-sized neurons (15-35 mum) predominate at rostral levels. However, neurons of all sizes are present throughout the nucleus. Following lesions of the nucleus, the course of degenerating axons stained with the Fink-Heimer method has been traced throughout the brainstem and spinal cord. The rubrospinal tract crosses the midline, courses past the ventrocaudal aspect of the contralateral nucleus ruber, and then descends rostro-ventral and lateral to the nucleus tegmenti pontinus. In its caudal continuation the tract lies ventral to the brachium conjunctivum and the entering radix of the trigeminal nerve. It then assumes a ventrolateral position in the caudal brainstem before shifting to a dorsolateral position in the lateral funiculus of the spinal cord. Within the spinal grey the rubrospinal tract terminates in laminae V, VI and to a lesser extent VII. The possibility of a topographical organization of the nucleus was investigated with injections of horseradish peroxidase into brachial, thoracic and lumbar spinal cord. Regardless of the level of injection, labelled neurons of all sizes were present throughout the contralateral nucleus ruber, indicating the absence of an obvious topography.

Animals↗
PubMed1979

The discrete anatomical localization of vagal aortic afferents within a catecholamine-containing cell group in the nucleus solitarius.

The centripetal transport of horseradish peroxidase (HRP) was used to visualize the central projections of afferent fibers of the aortic arch nerve to the nucleus solitarius in pigeons. Our results indicate that aortic nerve afferents have a restricted distribution within one subdivision of the nucleus solitarius, designated the subnucleus sulcalis dorsalis. Histofluorescence studies revealed that the aortic nerve projection area is extremely rich in catecholamine-containing neurons.

Afferent Pathways↗
PubMed1979

Accessory optic projections upon oculomotor nuclei and vestibulocerebellum.

Displaced retinal ganglion cells in birds are the sole source of the retinal projection onto the nucleus of the basal optic root, the main component of the accessory optic system. This nucleus has direct bilateral axonal projections onto the oculomotor nuclear complex, the trochlear nucleus- and folia IXc,d and paraflocculus of the vestibulocerebellum. The cerebellar projection terminates within a superficial band of the granule cell layer adjacent to the Purkinje cell layer as a mossy fiber system. This bisynaptic projection onto oculomotor neurons and the cerebellum may play a functionally distinct and specific role in oculomotor reflexes.

Animals↗
PubMed1979

Enkephalin-containing amacrine cells in the avian retina: immunohistochemical localization.

The distribution of enkephalin-like immunoreactivity within the avian retina was studied by immunofluorescence and immunoperoxidase techniques with antiserum to [Met5]enkephalin and [Leu5]enkephalin. Formaldehyde-fixed retinae were sectioned and incubated in antiserum to either [Met5]- or [Leu5]enkephalin. Specificity to the antiserum was established by absorption of the antiserum with synthetic [Met5]- or [Leu5]enkephalin at 1 mM. Positive immunohistochemical staining for enkephalin was observed in the somata of amacrine cells and their processes within the inner plexiform layer. A large number of enkephalin-containing amacrine cells were distributed throughout the retina, and their density appeared to be greatest within central retinal regions. The majority of labeled amacrine cells were about 7.5 micrometers in diameter although, occasionally, amacrine cells were observed that were 12--15 micrometers in diameter. Amacrine cells had a cell-to-cell spacing of approximately 40 micrometers within central retinal regions. Labeled processes of the amacrine cells were observed to project into the inner plexiform layer where they arborized as a fine plexus, within laminae 1, 3--5 of the inner plexiform layer. These observations demonstrate the existence of opioid peptides in seemingly select populations of amacrine cells within the retina. The localization of enkephalin-like immunoreactivity within the retina suggests that opioid peptides play a specific and unique functional role in retinal processing.

Animals↗
PubMed1978

The trigeminal system in the pigeon (Columba livia). I. Projections of the gasserian ganglion.

The central projections of the Gasserian ganglion were investigated in the pigeon, Columba livia. Lesions were placed in the ganglion either by direct surgical exposure or stereotaxically, and following survival times of one to four days, the brains stained with the Fink-Heimer method. The main group of central axons bifurcate to form distinct ascending and descending branches, the tractus trigemini ascendens (TTA) and the tractus trigemini descendens (TTD). A smaller tract also courses caudally (ITTD) separate of TTD proper to terminate in the nucleus cuneatus externus. The TTA projects topographically upon the principal sensory nucleus of the trigeminus, ending in both the pars dorsalis and a smaller pars ventralis. The neurons at the point of bifurcation of the entering radix have been designated as the pars oralis of nTTD. The TTD distributes caudally to several distinct subnuclei at each level, and extends into the cervical spinal cord. Relatively discrete regions corresponding to the pars interpolaris and caudalis were recognized. The projections to the cervical cord terminate in laminae I-IV. There was no evidence of projections to the cerebellum, or contralateral PrV or TTD. There was a small projection to the contralateral cervical spinal cord. No clear evidence of a projection to the nucleus solitarius was found. The distribution of primary trigeminal axons is compared to that described in other vertebrates.

Animals↗
PubMed1976

Central projections of the chorda tympani nerve in the mallard, Anas platyrhynchos L.

The central projections of the chorda tympani nerve in the duck were studied by means of the Fink-Heimer technique. Following section of the VIIth nerve proximal to the geniculate ganglion terminal projections of the CT are found in the sensory nucleus N VII (sVIId) on the dorsum of the descending trigeminal root, the n. presulcalis anterior solitarii, the n. sulcalis anterior solitarii p. dorsalis and p. ventralis, and the n. ventrolateralis anterior solitarii (Vla). Small quantities of terminal degeneration are also found in the n. intermedius anterior and the lateral substantia gelatinosa of the solitary complex. A number of fibers decussate to terminate contralaterally in corresponding portions of the opposite solitary complex. Comparison with data of the pigeon reveals a limited overlap of projections of the chorda tympani nerve and of the nodose ganglion, respectively, in the dorsal and ventral parts of the n. sulcalis anterior. We suggest that the regions sVIId and Vla alone may convey gustatory information.

Afferent Pathways↗
PubMed1976

Organization of the tectofugal visual pathway in the pigeon: a retrograde transport study.

In birds, superficial laminae of the optic tectum receive a massive retinal input; the tectum in turn projects upon the nucleus rotundus thalami, which then sends its efferents to the ectostriatal core of the telencephalon. To examine the detailed organization of this principal ascending visual pathway, small injections of the marker horseradish peroxidase (HRP) were placed in various sites throughout the ectostriatum (E) or nucleus rotundus (Rt) in pigeons. Analysis of the resulting patterns of retrograde labeling indicates the tectofugal pathway to be comprised of at least five different channels. Cells which lie at various depths in the stratum griseum centrale (SGC) of the tectum project upon distinct subdivisions of nucleus rotundus. Anterior portions of Rt receive input from superficial-most cells in the SGC, while medial and more caudal portions of Rt are projected upon by deeper SGC neurons. A ventral subdivision of Rt was found to receive its primary input from two pretectal nuclei. Additional inputs to all portions of Rt arise from nucleus reticularis superior thalami. The various subdivisions of rotundus in turn project upon distinct portions of the ectostriatum. Thus, the segregation between the different input classes into Rt is largely retained at the telencephalic level. In contrast, the nucleus triangularis, a dorso-medial extension of Rt which receives its input from the deepest of all SGC neurons, sends its efferents to all parts of the ectostriatum.

Animals↗