PubMed Health⌕ Search

Biomedical subjects

X C Wan

Publications and source records attributed to X C Wan.

13 recordsLinked to original sources
PubMed1990

Cytoarchitecture and dendroarchitecture of sympathoadrenal preganglionic neurons in rats--a study with CB-HRP.

The cytoarchitecture and dendroarchitecture of sympathoadrenal preganglionic neurons (SAPN) that innervate the adrenal medulla have been studied in adult rats. Retrograde transport of choleragen subunit B horseradish peroxidase conjugate (CB-HRP) injected into the left adrenal medulla resulted in the labelling of SAPN in the ipsilateral intermediate zone from T1 to L1 segments. Four subnuclei of SAPN were distinguished and located in ILP, ILF, IC and ICPe of the spinal cord respectively. The dendritic trees of neurons in ILP exhibited dendritic patterns with extension oriented longitudinally and mediolaterally. The present findings provide detailed descriptions of the somatic structure and accompanying dendritic trees of SAPN. The observation also include anatomical evidence that two systems of circuits may exist in regulating the activities of SAPN; one is the classic core circuits system which mainly received the inputs from fibers in parallel direction with longitudinal dendrites in ILP and the other is the paralateral circuits system which chiefly received the inputs from fibers in perpendicular direction with radial dendrites in white matter.

Adrenal Medulla↗
PubMed1989

Improvement of the tetramethyl benzidine reaction with ammonium molybdate as a stabilizer for light and electron microscopic ligand-HRP neurohistochemistry, immunocytochemistry and double-labelling.

Ammonium heptamolybdate (AHM) was used as a stabilizing agent in the tetramethyl benzidine (TMB) reaction of choleragen subunit B conjugated horseradish peroxidase (CB-HRP) neurohistochemistry (TMB-AHM method). In comparison with Mesulam's TMB method employing sodium nitroprusside as a stabilizing agent (TMB-SNP method), the TMB-AHM procedure offers a similar sensitivity with regard to the visualization of CB-HRP labelled neurons and their extranuclear Golgi-phobic dendrites. However, it is less sensitive for the demonstration of anterogradely transported CB-HRP in axon terminals. At the nearly physiological pH value of the reaction medium (pH 6-8), it demonstrates better preservation of tissue and cell structures in the reacted sections. Under the electron microscope, the specific reaction product can be clearly distinguished and little damage of cellular and subcellular structures occurred. Preliminary application of TMB-AHM method to choleragen subunit B (CB) immunocytochemistry and double labelling technique which paired the neuronal tracing methods of HRP neurohistochemistry and CB immunocytochemistry, was also carried out with small modification.

Animals↗
PubMed1989

[Ammonium molybdate as stabilizing agent in tetramethyl benzidine reaction of CB-HRP neurohistochemistry and its application to electron microscopy and immunocytochemistry].

Ammonium molybdate (AHM) was used as a stabilizing agent in the tetramethyl benzidine (TMB) reaction of choleragen subunit B conjugated horseradish peroxidase (CB-HRP) neurohistochemistry. In comparison with Mesulam's TMB method using sodium nitroprusside (SNP) as stabilizing agent, this new stabilizer offers similar sensitivity in regard to visualization of CB-HRP labelled neurons and their extranuclear Golgi-phobic dendrites. The nearly physiological pH (6-8) of the reaction medium demonstrates better preservation of tissue and cell structures of reacted sections and avoids non-specific needle-like crystal formation. Under the electron microscope, the histochemical reaction products can be clearly distinguished, without the usual shrinkage or distention of cellular and subcellular structures. This method was also applied with success to immunocytochemistry through small modifications.

Animals↗
PubMed1982

Cholera toxin and wheat germ agglutinin conjugates as neuroanatomical probes: their uptake and clearance, transganglionic and retrograde transport and sensitivity.

Horseradish peroxidase (HRP) conjugates of 6 different lectins and cholera toxin (CTHRP) were quantitatively compared with respect to: (a) their behavior at the injection site and (b) their ability to label, by means of transganglionic and retrograde axonal transport, axon terminals and neurons in the medulla of the rat subsequent to injections of each probe into the anterior two thirds of the tongue. HRP conjugates of wheat germ agglutinin (WGHRP) and CTHRP were more sensitive than any of the other lectin-HRP conjugates. Both were far superior to free-HRP (FHRP) in demonstrating these projections and CTHRP was the most sensitive transganglionic and retrograde probe. Additional experiments demonstrated that this superiority was not an artifact of the volume of material injected into the tongue nor of the injection site area or survival time selection. These experiments demonstrated further that CTHRP and WGHRP remain at the injection site approximately twice as long as FHRP and that their removal from or degradation in retrogradely labeled neurons requires approximately twice as much time as that required for FHRP. These observations, together with earlier studies from this laboratory, suggest the following conclusions: (1) CTHRP and WGHRP are superior in sensitivity to FHRP for studies of neuronal connectivity; and (2) HRP conjugates of ligands such as CTHRP and WGHRP are internalized, transported and/or degraded by mammalian neurons in a manner which differs from that of FHRP, a macromolecule for which neuronal plasma membrane 'receptors' are lacking.

Afferent Pathways↗
PubMed1981

Double superior venae cavae associated with aberrant subclavian artery--the atavistic and transitional nature of "proximal loss" aortic arch.

A case of double superior venae cavae (Bvc) associated with bilateral azygos veins (Baz), aberrant subclavian artery (Sa) and other rare variations is recorded in a two-year-old Chinese girl with an unknown cause of death. A review of the literature since 1844 indicates that there has been no reported case of a right Sa associated with Bvc + Baz. The primitive arrangement of the thoracic large vessels in this case (Bvc + Baz and CHim type of aortic branches) substantiates the atavistic nature of Sa. The proximal loss pattern (PLdp) of the aortic arch with its associated Bvc + Baz was a primitive transitional link between the vascular arrangement of the Mesozoic reptilian and that of mammals or avians. According to this concept, there should be an occurrence of the PLdp variation (i.e. Sa) in all the mammals and avians and an occurrence of the 1-, 2- or 6-branch type of PLdp in human beings or in other animals.

Aorta, Thoracic↗