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Biomedical subjects

J Tigges

Publications and source records attributed to J Tigges.

At least 55 records · Page 3Linked to original sources
PubMed1981

Distribution of retinofugal and corticofugal axon terminals in the superior colliculus of squirrel monkey.

The distribution of terminal fields of retinocollicular fibers was studied in squirrel monkeys with the autoradiographic technique. The terminals were aggregated into patches which were separated by intervening gaps. The ipsilateral patches were particularly distinct. The patches as well as th gaps ranged in size from 50 to 200 microns. In the most posterior aspect of the contralateral superior colliculus, the gaps were absent, and the terminals formed an uninterrupted sheet. The corresponding portion of the ipsilateral colliculus had no retinal input, in agreement with the concept that this region most likely represented the temporal crescent of the visual field. In the most anterior portion of the superior colliculus where the fovea is known to be represented, the ipsilateral and contralateral projections were sparse but, nevertheless, discernible. There was a partial laminar segregation of terminals. The majority of the terminal fields in the contralateral colliculus was located in the most dorsal tier of the stratum griseum superficiale, whereas the majority of the ipsilateral input was slightly deeper in the same stratum. The distribution of corticocollicular fibers was studied by the autoradiographic technique. The fibers from areas 17 and 18 terminated predominantly in the dorsal portion of the stratum griseum superficiale. Area 19, in contrast, projected to the ventral portion of the stratum griseum superficiale. Thus the terminal fields of axons from the retina, area 17 and area 18, overlap in the superior colliculus, whereas axons arising from area 19 terminate in another substratum.

Animals↗
PubMed1980

Distribution and morphology of myelinated perikarya and dendrites in the olfactory bulb of primates.

Numerous myelinated perikarya occur in different layers of the olfactory bulbs of a chimpanzee and two species of New World primates, that is, the squirrel and the Cebus monkey. It appears that somata of all established neuron categories, except for the mitral cells, can become ensheathed in myelin. Myelinated dendritic segments are found in the periglomerular region and in the external plexiform layer; tufted and periglomerular cells most likely to give rise to these myelinated dendrites. The myelin sheath is predominantly of the compact C.N.S. type. Perikaryal and dendritic myelin often ends in typical feet of glial cytoplasm. The termination site of dendritic myelin is a preferred site of synaptic contacts. Myelinated profiles are more numerous in the two monkey species than in the chimpanzee.

Animals↗
PubMed1979

Efferents of area 4 in a South American monkey (Saimiri). I. Terminations in the spinal cord.

A single injection of either tritiated proline or a mixture of proline and leucine was made in area 4 of 8 squirrel monkeys. The locus of the injection was systematically varied from medial to lateral among animals. Autoradiographs revealed a strong contralateral lateral corticospinal tract. A sparsely labelled ipsilateral lateral tract was also present in all animals. In 2 animals, a few labelled fibers indicative of an ipsilateral anterior tract were observed; the fibers terminated at lumbar levels. Grain counts over the cervical and lumbar gray showed that area 4 efferents terminated contralaterally in laminae IV--IX with a peak in lamina VII; only sparse input was seen in the vicinity of the large alpha-motoneurons of lamina IX. On the ipsilateral side, the terminals were largely confined to lamina VIII. This pattern was in accordance with that reported in other primates. The terminal fields at sacral and coccygeal levels were radically different in that large numbers of fibers recrossed to the ipsilateral side and ended in laminae V through IX; the functional significance of this strong bilateral termination was discussed.

Animals↗
PubMed1979

[Prenatal sex determination by radioimmunoassay of testosterone with and without chromatography of the amniotic fluid (author's transl)].

Amniotic fluid testosterone measured by radioimmunoassay (RIA) without chromatography (immunoreactive testosterone) seems not to be a definitive test for prenatal sex determination in all cases. In this study testosterone (T) levels measured by RIA with chromatography of the amniotic fluid samples were compared with immunoreactive testosterone (iT) values, to determine the predictive accuracy of the two methods. In 111 amniotic fluid samples between 15 and 19 weeks of gestation iT and T were measured parallelly. There are significant differences between iT- and T-means of both sexes (p less than 0.001). 95%-condifence limits of iT-values of the male and female fetuses are largely overlapping. In contrast, the overlap of 95%-confidence limits of the T-values is only minor. The measurement of testosterone with chromatography of the amniotic fluid samples shows for prenatal sex determination in over 90% accuracy. This result is due to the elimination of sex-specific differences in crossreacting steroids within the amniotic fluid of both sexes.

Amniotic Fluid↗
PubMed1979

Types of degenerating geniculocortical axon terminals and their contribution to layer IV of area 17 in the squirrel monkey (Saimiri).

Radiofrequency lesions were made in the lateral geniculate nuclei of six squirrel monkeys. The resulting degenerating terminals and their postsynaptic structures in layer IV of area 17 were quantitatively categorized on photomontages covering large areas of neuropil. Two to five days after the lesion, numerous axon terminals were affected by a variety of degenerative changes, i.e., enlargement and distortion of synaptic vesicles, neurofilamentous hyperplasia, electron-lucent and electron-dense reactions. Based on the aggregation of electron-dense material beneath the postsynaptic membrane, the degenerating terminals were considered to be of the asymmetric type. Among the degenerating boutons were the largest axon endings that occur in layer IV. Three days postoperatively, degenerating boutons contributed an average of 16.2% to the total synapse population; five days postoperatively, the average had increased to 19.3%. The percentage of degenerating boutons on individual montages, however, amounted to as much as 29%. This amount probably reflects more closely the actual contribution of the geniculocortical fiber system to layer IV of striate cortex. The postsynaptic structure most frequently contacted by degenerating axon endings was the dendritic spine, followed by dendrites of small diameter. To account for the diversity of degenerative changes in the same fiber system, we offer the tentative suggestion that heterogeneously degenerating axon terminals arise from a heterogeneous population of neurons in the lateral geniculate nucleus, i.e., from magnocellular versus parvocellular laminae.

Animals↗
PubMed1979

Subarachnoid space of the CNS, nasal mucosa, and lymphatic system.

We have briefly reviewed the literature pertaining to the movement of tracer molecules and infectious organisms within the olfactory nerve. There is a body of evidence indicating that tracers placed in the CSF will quickly move via the olfactory nerve to the nasal mucosa and then to the cervical lymph nodes. Organic and inorganic tracer materials and organisms as diverse as viruses, a bacillus, and an amoeba, when placed in the nasal cavity, have been shown to move from the nasal mucosa via the olfactory nerve to the olfactory bulb and the CSF. We think that a portion of the data on tracer movement is due to incorporation of tracer materials and organisms into the axoplasm of the olfactory neurons with subsequent anterograde or retrograde axoplasmic transport. However, some of the movement of tracers may occur within the olfactory perineural space. This space may be continuous with a subarachnoid extension that surrounds the olfactory nerve as it penetrates the cribriform plate. To our knowledge, no one has yet followed the perineural space to determine if it is continuous from olfactory receptor to olfactory bulb. The consideration of this space and its role is the main reason for this review.

Animals↗
PubMed1979

Neurons with presynaptic somatic protrusions in the visual cortex of monkeys.

In layer IV of the visual cortex of two primate species three small neurons were found that gave rise to short presynaptic somatic protrusions. The protrusions contained a cluster of predominantly round vesicles and established asymmetrical synaptic contacts with the characteristics of Gray's type 1 terminals.

Animals↗
PubMed1978

[Ultrasonographic monitoring of ovarian hyperstimulation by exogenous gonadotropins and subsequent twin-pregnancies (author's transl)].

In contrast to estrogen-monitoring the ultrasonographic monitoring of the ovaries renders possible the estimation of individual follicular growth stimulated by gonadotropins. In two patients suffering from anovulation and additional factors inhibiting fertility, ultrasonographic monitoring was used in order to induce a pregnancy after moderate hyperstimulation nevertheless.

Adult↗
PubMed1977

Complementary laminar terminations of afferents to area 17 originating in area 18 and in the lateral geniculate nucleus in squirrel monkey.

The projections from area 18 and the lateral geniculate nucleus onto area 17 of the squirrel monkey (Saimiri) were investigated with retrograde (horseradish peroxidase) and anterograde (tritiated proline) labelling techniques, and the (Fink-Heimer) silver impregnation method for degenerating axons and their terminals. The association fibers from area 18 terminated in all layers of area 17 except in layer IV and in the lower aspect of layer IIIc. The greatest number of terminals were in layers I, V and VI. The bulk of geniculocortical fibers terminated in layer IV and the lower aspect of layer IIIc; a minority of the geniculocortical fibers terminated in layer VI and the lower aspect of layer IIIb. Thus, the majority of fibers from the two sources investigated terminate in a complementary laminar fashion in area 17. The portion of area 17 on the lateral surface of the hemisphere, where the central visual field is represented, received a less dense projection from the geniculate nucleus than the striate cortex in the calcarine fissure, where the peripheral visual field is represented. Ocular dominance columns were not apparent in the striate cortex. No evidence was found that the lateral geniculate nucleus projects to area 18. The results of combined injections of horseradish peroxidase and tritiated proline in area 17 indicated a point-to-point reciprocity between area 17 and the ipsilateral lateral geniculate nucleus.

Animals↗
PubMed1977

An autoradiographic investigation of the subcortical visual system in chimpanzee.

Based on one adult chimpanzee monocularly injected with radioactive proline, retinofugal fibers were found to terminate bilaterally in the suprachiasmatic, pregeniculate, lateral geniculate, olivary, pretectal and lateral terminal nuclei, and the superior colliculi; the existence of a dorsal terminal nucleus of the accessory optic system is in doubt. In the ipsilateral geniculate nucleus, the fibers terminate in layers 2, 3 and 5; in the contralateral nucleus, they end in layers 1, 4 and 6. Midway through the geniculate nucleus, layers 3 and 4 split medially into two daughter layers each. In the superior colliculi, most of the retinal terminals are aggregated superficially in a band located in the stratum griseum superficiale. The contralateral band is interrupted by gaps; the ipsilateral band has fewer gaps, is slightly thicker and located more deeply. There is a limited second tier of terminals in the contralateral superficial gray.

Animals↗
PubMed1975

Presynaptic dendrite cells and two other classes of neurons in the superficial layers of the superior colliculus of the chimpanzee.

In the superior colliculus of chimpanzee, three classes of neurons can be identified by ultrastructural criteria. They are 1) marginal cells located in the stratum zonale, 2) collicular relay cells in the stratum griseum superficiale and 3) presynaptic dendrite (PSD) cells, i.e., neurons with presynaptic specializations in soma and/or dendrites. PSD cells are the smallest neurons in the stratum griseum superficiale; they have a relatively large, deeply infolded nucleus and a small rim of cytoplasm rich in free ribosomes. PSD cells are sufficiently different from the two other classes of neurons to be reliably identified at the ultrastructural level. They closely resemble presynaptic neurons as described in the lateral geniculate nucleus of other mammalian species. Presynaptic dendrites in continuity with PSD cells are rich in organelles, especially ribosomal cluster, and establish en passage contact with other dendrites. Another type of presynaptic dendrite, poor in organelles, except for bundles of microtubules, could not be traced back to its parent neuron. Homo- or heterogeneity of PSD cells is discussed. No amxon was traced from a PSD cell.

Animals↗
PubMed1975

Tilt analysis of pleomorphic vesicles in the superficial layers of the superior colliculus of Galago and chimpanzee.

Pleomorphic vesicles in two different classes of 'flat-vesicle-containing profiles'(F-profiles) from the superficial layers of the superior colliculus of Galago and chimpanzee were found to be disk-like in shape as revealed by tilt analysis. In both primates, presynaptic dendrites, postsynaptic F-profiles and exclusively presynaptic F-profiles cannot be distinguished on the basis of vesicle morphology. This lends to support to the notion that F-profiles originate from one type of neuron. Modifications of the basic disk shape are interpreted as manifestations of different stages in the life cycle of individual vesicles.

Animals↗