Avtor/Urednik		Milanič, Tanja; Kunstelj, Andrej; Marš, Tomaž; Grubič, Zoran
Naslov		Morphometric characteristics of myonuclear distribution in the normal and denervated fast rat muscle fiber
Tip		članek
Vir		Chem Biol Interact
Vol. in št.		Letnik 119-120
Leto izdaje		1999
Obseg		str. 321-6
Jezik		eng
Abstrakt		Unlike the majority of mammalian tissues, which have mononuclear cells as a basic unit of the tissue composition, skeletal muscle fiber is a polynuclear syncytium. Polynuclear organization offers an additional possibility for the regulation of protein expression: it can also be controlled at the level of myonuclear distribution and specialization. Distribution of myonuclei can be considered as the distribution of genes. Variability in gene concentration may have important impact on the regional differentiation of the muscle fiber, since it leads to different regional concentrations of various gene products including factors controlling their expression. The aim of the present study was:1) to provide morphometrical data on the myonuclear distribution in the junctional and extrajunctional regions of the normal fast rat muscle fiber, and 2) to analyze, whether morphomertical parameters of nuclear distribution change after mechanicai denervation of this muscle. Single muscle fibers were isolated from the normal and denervated fast rat m. sternomastoideus. Their neuromuscular junctions were stained by thiocholine histochemical procedure and myonuclei were auorescently lebeled by Hoechst 33342. Myonuclear distribution in each individual muscle fiber was morphometrically analyzed on the image analyzer. Synaptic concentrations of myonuclei were found to exceed extrasynaptic concentrations by a factor of 17. The number of myonuclei accumu- lated at the endplates did not change after one or two weeks of denervation, neither did the morphometric parameters of these nuclei. A higher concentration of myonuclei due to muscle atrophy was observed in the extrasynaptic region and the longitudinal axis of these nuclei also became significantly shorter.
Deskriptorji		MUSCLE FIBERS, FAST-TWITCH NEUROMUSCULAR JUNCTION RATS, WISTAR CELL NUCLEUS MUSCLE DENERVATION MICROSCOPY, FLUORESCENCE MUSCLE PROTEINS NECK MUSCLES SYNAPSES