The lateral cervical nucleus in the cat

Summary Profiles of 14 neurons all sectioned through the nucleolar plane and 87 isolated dendritic profiles have been analyzed with respect to the surface area covered by boutons and astroglial processes. This analysis has revealed two different types of neurons within the lateral cervical nucleus (LCN) of the cat. The cell types also differ in other ultrastructural respects. One type, which probably consists of projection neurons, is characterized by a rather large size, a relatively small nucleus, numerous mitochondria, well developed granular and agranular endoplasmic reticulum. The cell membrane of these cells shows somatic spines and the perikaryon is covered with boutons to a mean extent of 42%. The other cell type, which probably is internuncial, is smaller, has a proportionally larger nucleus, few mitochondria and a poorly developed granular and agranular endoplasmic reticulum. These cells show no somatic spines and the perikaryal membrane is covered with boutons to an extent of about 10%. Also the bouton populations contacting the two cell types differ from one another. The proportion of internuncial neurons within the LCN has been estimated to about 8%. The internuncial neurons seem to have no preferential localization.The primary dendrites of the projection neurons have a bouton covering of about 48%. No proportional differences in covering could be revealed between different sizes of dendrites.The results are discussed in relation to what is known about the anatomical and physiological organization of the LCN, and also compared with the results obtained in other similar investigations on other parts of the central nervous system.The author is grateful to fil.kand. Göran Engholm for his help with the statistical considerations.This work was supported by grants from Anders Otto Swärds Stiftelse, Stiftelsen Lars Hiertas minne, Åhlén och Holms stiftelse, Åke Wibergs stiftelse and the Swedish Medical Research Council (Project No B70-12X-2710).     

Projection linkage from spinal neurons to both lateral cervical nucleus and solitary tract nucleus in the cat

Intracellular recordings from the lumbosacral dorsal horn were made to identify the axonal projection and the afferent innervation of the lateral cervical nucleus (LCN) and solitary tract nucleus (STN) on the spinal neurons of chloralose-anesthetized cats. A total of 49 neurons from laminae III-V in the spinal dorsal horn responded to stimulation of both the LCN and STN. Of these, 28 and 21 neurons responded antidromically and orthodromically to stimulation of the LCN and STN, respectively. Seven of the 28 antidromically activated neurons were followed by one or more responses synaptically driven from the LCN and/or STN. The diameter of these ascending or descending fibers was in the range of A delta fibers. The results indicate that (1) some spinal neurons, namely spinocervical tract-spinosolitary tract (SCT-SST) neurons, issue branched axons of A delta-fibers and dually project to both LCN and STN; (2) some SCT-SST neurons receive innervation from both the LCN and STN; (3) some spinal neurons and interneurons are dually innervated by descending fibers originating from both the LCN and STN, and (4) the convergence and integration between somatic and visceral sensory inputs might occur in the SCT-SST neurons.     

Synaptic terminals in the ventroposterolateral nucleus of the thalamus from neurons in the dorsal column and lateral cervical nuclei: an electron microscopic study in the cat

Brain Cell Biology - The afferent fibres to the ventroposterolateral nucleus (VPL) of the contralateral thalamus from neurons in the dorsal column nuclei (DCN) and the lateral cervical nucleus...     

A quantitative study of synaptic interconnections in the dorsal lateral geniculate nucleus of the cat

Summary 2,700 synaptic contacts have been classified according to criteria described in an accompanying paper and the results summarized in tabular form. Only about 20% of the synaptic contacts in laminae A and A1 are formed by axons identifiable as retinogeniculate fibers. About 1/4 of these retinogeniculate synapses are axo-axonal. Approximately 45% of the contacts in these laminae are formed by axons tentatively identifiable as corticogeniculate fibers; about 35% by presumed intrageniculate fibers. Close to one half of the synapses occur in encapsulated synaptic zones, where grapelike dendritic appendages are related mainly to intrageniculate and retinogeniculate axons, and about half lie in interstitial zones, where corticogeniculate and some intrageniculate axons contact distal dendritic segments.Regions of the nucleus receiving from peripheral parts of the retina have relatively more corticogeniculate synapses, and have fewer intrageniculate synapses in the encapsulated zones than do regions receiving from the central parts of the retina.Most of the tissue in lamina B resembles the interstitial zones of laminae A and A1 and over 2/3 of the contacts in lamina B may prove to be corticogeniculate. The retinogeniculate fibers in this lamina are associated with relatively few other axons in simple, small encapsulated zones.Supported by Grant NB 06662 from the USPHS. The skillful technical assistance given by Mrs. E. Langer during the course of this work is gratefully acknowledged.     

A light and electron microscopical study of the green flagellateSpermatozopsis similis spec. nova

The green flagellateSpermatozopsis similis spec. nova has been studied in culture by light and electron microscopy. The flagellate bears two flagella, is naked and has a characteristic crescent and spirally twisted cell shape. The two flagella are of subequal length, each with a prominent hair-point. Each cell contains two contractile vacuoles, a single chloroplast with an anterior eyespot but lacking a pyrenoid, an anteriorly located nucleus, a single dictyosome associated with the posterior end of the nucleus, a single mitochondrion posterior to the nucleus and associated with a small microbody, some conspicuous vacuoles, and a greater number of secondary cytoskeletal microtubules which probably are responsible for maintaining the peculiar shape of this species. SinceS. similis in culture is only biflagellate, it cannot be accommodated within the quadriflagellate, but otherwise very similar speciesS. exsultans. Spermatozopsis similis is compared with other green flagellates and is shown to share common ultrastructural characters withChlamydomonas-type green algae.     

A study on amitosis of the nucleus of the mammalian cell. I. A study under the light and transmission electron microscope

The experiments were conducted on two species of experimental animals: mice and rats. The mice were poisoned by CCl4, whereas the rats had a hepatectomy in order to remove a larger part of the left lobe of the liver. 5 samples of human liver cancer tissue were examined by routine methods. The phenomena of amitosis were studied. In addition to more features of amitosis, many intranuclear structures characteristic of amitosis were found in the carcinoma tissue. The authors propose to divide the nuclear amitosis process into 4 stages and try to design a diagrammatic picture of amitosis in order to illustrate that also by amitosis chromatin can be reproduced and equally distributed to the daughter cells, so that the continuity and precision of gene threads is guaranteed in the daughter cells. The study discusses the functional significance of nuclear amitosis.     

A light and electron microscopical study of spermatogenesis in Hydra cauliculata

Morphological changes in the interstitial cells were studied during their differentiation into spermatozoa. Development of the spermatogonium involves an increase in nuclear and nucleolar size, and the formation of a dense mass of cytoplasmic ribosomes. The mature spermatozoon has a relatively simple structure. The head consists of a bullet shaped, homogeneous nucleus, which lacks an acrosome but bears distal membrane specializations. The middle piece is composed of four large spherical mitochondria at the base of nucleus. A single flagellum projects from one of the two centrioles lodged between the mitochondria. The flagellum appears early during development in the primary spermatocyte. During spermiogenesis microtubules associated with the basal body flagellum complex appear to define the axis of chromatin condensation.     

Alterations of alveolar type II cells and intraalveolar surfactant after bronchoalveolar lavage and perfluorocarbon ventilation. An electron microscopical and stereological study in the rat lung

Background

Repeated bronchoalveolar lavage (BAL) has been used in animals to induce surfactant depletion and to study therapeutical interventions of subsequent respiratory insufficiency. Intratracheal administration of surface active agents such as perfluorocarbons (PFC) can prevent the alveolar collapse in surfactant depleted lungs. However, it is not known how BAL or subsequent PFC administration affect the intracellular and intraalveolar surfactant pool.

Methods

Male wistar rats were surfactant depleted by BAL and treated for 1 hour by conventional mechanical ventilation (Lavaged-Gas, n = 5) or partial liquid ventilation with PF 5080 (Lavaged-PF5080, n = 5). For control, 10 healthy animals with gas (Healthy-Gas, n = 5) or PF5080 filled lungs (Healthy-PF5080, n = 5) were studied. A design-based stereological approach was used for quantification of lung parenchyma and the intracellular and intraalveolar surfactant pool at the light and electron microscopic level.

Results

Compared to Healthy-lungs, Lavaged-animals had more type II cells with lamellar bodies in the process of secretion and freshly secreted lamellar body-like surfactant forms in the alveoli. The fraction of alveolar epithelial surface area covered with surfactant and total intraalveolar surfactant content were significantly smaller in Lavaged-animals. Compared with Gas-filled lungs, both PF5080-groups had a significantly higher total lung volume, but no other differences.

Conclusion

After BAL-induced alveolar surfactant depletion the amount of intracellularly stored surfactant is about half as high as in healthy animals. In lavaged animals short time liquid ventilation with PF5080 did not alter intra- or extracellular surfactant content or subtype composition.     

The coating of mouse myocardial cells. A cytochemical electron microscopical study.

The coating of mouse myocardial cells has been investigated with a variety of cytochemical methods. The coating of the surface membrane gives a positive reaction with ruthenium red, colloidal thorium, phosphotungstic acid (PTA) at low pH, silver methenamine after periodic oxidation (PA-silver technique) and with silver proteinate after periodic oxidation and thiocarbohydrazide treatment (PA-TCH-silver technique). The coating of the T system gives almost similar results. The nexuses do not react with PTA nor with the PA-silver and PA-TCH-silver techniques, but they are strongly stained with ruthenium red which reveals periodic structures in their gaps. The specificities of the colloidal thorium technique and PAT staining have been tested by chemical treatments (methylation, acetylation, saponification), enzymatic digestions (pronase, trypsin, hyaluronidase, neuraminidase) and carbohydrate extractions (with 0.1 N NaOH and 0.05 M H2SO4). These cytochemical data indicate, considering the specificity of the reactions, that the coating of the membrane surface and the T system contains polyanionic groups. A part of them, at least, would belong to a carbohydrate-containing material (glycoproteins), whereas at the level of nexuses the sugar residues would probably be absent.     

Tailoring of variability in the lateral geniculate nucleus of the cat

 Variability is usually considered an unwanted component in a sensory signal, yet the visual system does not seem to filter out the noise. On the contrary, noise is ‘tailored’ to scale with the signal size. We show that this tailoring occurs in the lateral geniculate nucleus, preferentially in X-cells, which are the cells most likely to transmit pattern information. Tailoring the variability to the signal size may be the visual system’s way of providing the right amount of variability for a signal of any magnitude at all times during the computation. Received: 13 November 1995/Accepted in revised form: 20 May 1996     

A projection from the raphe nuclei to the lateral reticular nucleus in the cat

By means of retrograde transport of the wheat germ agglutinin-horseradish peroxidase complex afferent fibres to the lateral reticular nucleus from the raphe nuclei were demonstrated in the cat. The projection is bilateral and has its main origin in nucleus raphe pallidus and magnus, but there appear to be contributions also from nucleus raphe obscurus, dorsalis and linearis rostralis.     

Organization of the ferret lateral cervical nucleus and cervicothalamic tract

To elucidate the organization of the ferret spinocervicothalamic pathway (SCTP), we examined the lateral cervical nucleus (LCN) and the termination of the cervicothalamic tract (CTY) in this species. In thionin-stained sections, the ferret LCN appeared as an easily delineated column of cells in the dorsolateral funiculus from about mid-C3 to the rostral end of C1, with most cells located in the C1 and C2 segments. In transverse sections, the LCN was elongated along a dorsolateral to ventromedial axis and in the rostral half of C2 and caudal half of C1 continuous with the neck of the dorsal horn. The number of ferret LCN cells was estimated to 2,500-3,700, with an average of 3,340. Substance P-like immunoreactive fibers located preferentially in the ventromedial part of the LCN, whereas serotonin-like immunoreactive fibers were found throughout the nucleus. Anterograde transport of wheat germ agglutinin-horseradish peroxidase conjugate and biotinylated dextran amine demonstrated that the ferret CTT terminates extensively in the peripheral parts of the ventral posterior lateral nucleus. Sparser termination was evident in the ventral posterior inferior nucleus, in the medial nucleus of the posterior complex, and in the medial part of the magnocellular medial geniculate nucleus. Thus, although the LCN is significantly smaller in ferrets than in cats and raccoons, the organization of the LCN and of the cervicothalamic tract is closely similar in the three species. These findings indicate a conserved general organization of the SCTP among carnivores.     

Organization of the ferret lateral cervical nucleus and cervicothalamic tract

To elucidate the organization of the ferret spinocervicothalamic pathway (SCTP), we examined the lateral cervical nucleus (LCN) and the termination of the cervicothalamic tract (CTT) in this species. In thionin-stained sections, the ferret LCN appeared as an easily delineated column of cells in the dorsolateral funiculus from about mid-C3 to the rostral end of C1, with most cells located in the C1 and C2 segments. In transverse sections, the LCN was elongated along a dorsolateral to ventromedial axis and in the rostral half of C2 and caudal half of C1 continuous with the neck of the dorsal horn. The number of ferret LCN cells was estimated to 2,500-3,700, with an average of 3,340. Substance P-like immunoreactive fibers located preferentially in the ventromedial part of the LCN, whereas serotonin-like immunoreactive fibers were found throughout the nucleus. Anterograde transport of wheat germ agglutinin-horseradish peroxidase conjugate and biotinylated dextran amine demonstrated that the ferret CTT terminates extensively in the peripheral parts of the ventral posterior lateral nucleus. Sparser termination was evident in the ventral posterior inferior nucleus, in the medial nucleus of the posterior complex, and in the medial part of the magnocellular medial geniculate nucleus. Thus, although the LCN is significantly smaller in ferrets than in cats and raccoons, the organization of the LCN and of the cervicothalamic tract is closely similar in the three species. These findings indicate a conserved general organization of the SCTP among carnivores.