Morphology of physiologically identified slowly adapting lung stretch receptor afferents stained with intra-axonal horseradish peroxidase in the nucleus of the tractus solitarius of the cat. II. An ultrastructural analysis

1985 ◽  
Vol 241 (4) ◽  
pp. 521-535 ◽  
Author(s):  
Madhu Kalia ◽  
Diethelm Richter
Author(s):  
I. Brent Heath

Detailed ultrastructural analysis of fungal mitotic systems and cytoplasmic microtubules might be expected to contribute to a number of areas of general interest in addition to the direct application to the organisms of study. These areas include possibly fundamental general mechanisms of mitosis; evolution of mitosis; phylogeny of organisms; mechanisms of organelle motility and positioning; characterization of cellular aspects of microtubule properties and polymerization control features. This communication is intended to outline our current research results relating to selected parts of the above questions.Mitosis in the oomycetes Saprolegnia and Thraustotheca has been described previously. These papers described simple kinetochores and showed that the kineto- chores could probably be used as markers for the poorly defined chromosomes. Kineto- chore counts from serially sectioned prophase mitotic nuclei show that kinetochore replication precedes centriole replication to yield a single hemispherical array containing approximately the 4 n number of kinetochore microtubules diverging from the centriole associated "pocket" region of the nuclear envelope (Fig. 1).


Author(s):  
John L. Beggs ◽  
John D. Waggener ◽  
Wanda Miller

Microtubules (MT) are versatile organelles participating in a wide variety of biological activity. MT involvement in the movement and transport of cytoplasmic components has been well documented. In the course of our study on trauma-induced vasogenic edema in the spinal cord we have concluded that endothelial vesicles contribute to the edema process. Using horseradish peroxidase as a vascular tracer, labeled endothelial vesicles were present in all situations expected if a vesicular transport mechanism was in operation. Frequently,labeled vesicles coalesced to form channels that appeared to traverse the endothelium. The presence of MT in close proximity to labeled vesicles sugg ested that MT may play a role in vesicular activity.


Author(s):  
D. R. Abrahamson ◽  
P. L. St.John ◽  
E. W. Perry

Antibodies coupled to tracers for electron microscopy have been instrumental in the ultrastructural localization of antigens within cells and tissues. Among the most popular tracers are horseradish peroxidase (HRP), an enzyme that yields an osmiophilic reaction product, and colloidal gold, an electron dense suspension of particles. Some advantages of IgG-HRP conjugates are that they are readily synthesized, relatively small, and the immunolabeling obtained in a given experiment can be evaluated in the light microscope. In contrast, colloidal gold conjugates are available in different size ranges and multiple labeling as well as quantitative studies can therefore be undertaken through particle counting. On the other hand, gold conjugates are generally larger than those of HRP but usually can not be visualized with light microscopy. Concern has been raised, however, that HRP reaction product, which is exquisitely sensitive when generated properly, may in some cases distribute to sites distant from the original binding of the conjugate and therefore result in spurious antigen localization.


Author(s):  
Gerald Rupp

The marine protozoan Allogromia sp, strain NF Lee extends an elaborate reticulopodial network (RN) which contains an elongate microtubule-(MT)-based cytoskeleton. The MTs are located primarily within cytoplasmic fibrils which are visible by light microscopy (LM) in highly flattened or “two dimensionalized” reticulopodia. It was shown previously that allogromiid RNs withdraw in response to hypertonic Mg2+-seawater. An ultrastructural analysis of this phenomenon indicated that large patches of paracrystalline (PC) material, composed of helical filament aggregates, form concomitant with a decrease in MT number. Similar large patches of PC aggregates are also found in juvenile Allogromia before they extend a RN, which disappear during RN formation. Finally, PC aggregates are occasionally seen near microtubules in normal untreated RNs. Thus there is circumstantial evidence to propose that PC aggregates in Allogromia represent an intermediate form of tubulin; however, more definitive biochemical or immunocytochemical data is not available.


Sign in / Sign up

Export Citation Format

Share Document