A study of motor nerve terminals on cat nuclear bag<sub>1</sub> intrafusal muscle fibers using the ChE staining technique

Kučera, Jan

doi:10.1002/ar.1092020313

Cited by 14 publications

(2 citation statements)

References 26 publications

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“…It is of interest to note that the intrafusal spindle fibers (nuclear bag fibers) have been shown to exhibit dual ATPase activity (Yellin 1969;Kucera 1982) as well as systematic morphological and histochemical variability (Kucera et al 1978;Kucera and Dorovini-Zis 1979;Kucera 1982). These fibers also contain both plate and diffuse endings; the plate ending being analogous to the typical endplate whereas the diffuse ending is comparable to the superficial ending seen to innervate the MIFs of the global layer and OSL in rat EOM.…”

Section: Discussionmentioning

confidence: 99%

Rat extraocular muscle

Pachter

1984

Histochemistry

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Multiply-innervated fibers from rat superior oblique extraocular muscle were followed in sequential serial sections using histochemistry. Sudan black and adenosine-triphosphatase (ATPase) histochemical staining reactions were used to identify these fibers in the muscle's global layer and orbital surface layer. Regional differences in ATPase staining occurred along the length of multiply-innervated fibers from the orbital surface layer. In their middle third where these fibers appear 'morphologically-fast' and contain endplatelike endings, they were found to exhibit a dual ATPase activity. In their distal third where they appear 'morphologically-slow' and contain simple, superficial endings, they had an alkaline-labile and acid-stabile ATPase activity profile. In contrast, the multiply-innervated fibers of the global layer exhibited a homogeneous ATPase activity, i.e., alkaline-labile and acid-stabile pattern. This histochemical homogeneity parallels their uniform morphologically-slow profile. These fibers contain only multiple superficial endings. It would appear that the histochemical and ultrastructural profile of a fiber is dependent upon the type and location of the motor innervation.

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Section: Discussionmentioning

confidence: 99%

Rat extraocular muscle

Pachter

1984

Histochemistry

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“…It may be that this reflects differences in the electrical and contractile activity of the muscle-fibre types (Pachter & Eberstein 1983). The factor of distance from the primary ending appears to operate regardless of fibre type such that the greater the distance, the higher the ChE content of an ending (Kucera 1982c), and the greater the amount of junctional folding. It follows from this, and from our own data on indentation, that maximal primary and secondary folding should be found in motor endings supplied to long chain fibres in region C, and the observations of Arbuthnott et al (1982, their 'md plate ') and Kucera & Hughes (1983 a) confirm this.…”

Section: Postsynaptic Featuresmentioning

confidence: 99%

Form and classification of motor endings in mammalian muscle spindles

Banks

Barker

Stacey

1985

Proc. R. Soc. Lond. B.

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The presynaptic features of 234 motor endings supplied to cat hindlimb muscle spindles have been studied in teased, silver preparations, and the postsynaptic features of a further 27 endings have been studied in serial, 1 μm thick, transverse sections. In the presynaptic study motor endings received by the three types of intrafusal muscle fibre were compared with the endings supplied to spindles by the various functional categories of motor axon. Three forms of motor ending were found that had significantly different presynaptic features. These forms correspond closely to those previously identified in the literature as p 1 (β), p 2 (dynamic γ) and trail (static γ). The results of the postsynaptic study showed that the degree of indentation of the intrafusal muscle fibres by motor axon terminals increases with greater distance from the primary ending, irrespective of muscle-fibre type. We conclude that the postsynaptic form of intrafusal motor endings is determined by distance from primary ending and muscle-fibre type. It is not determined by type of motor axon, and cannot be correlated with presynaptic form so as to produce a unified classification of intrafusal motor endings.

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Histological study of motor innervation of nuclear bag₁ intrafusal muscle fibers in the cat

Kučera¹

1985

J of Comparative Neurology

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The nerve supply to spindles of the cat tenuissimus muscle was reconstructed with light and electron microscopy of serial transverse sections. Fifty-two poles of the nuclear bag1 intrafusal muscle fiber were examined for motor innervation. The fiber poles were supplied by 71 myelinated motor axons that either terminated on bag1 fibers exclusively (93%) or coinnervated a chain fiber of the same intrafusal bundle (7%). No axons coinnervated both the bag1 and bag2 fibers. The unmyelinated preterminal segments of the axons were frequently short. Lengths and pre- and postsynaptic features of motor endings on bag1 fibers were variable. These features did not permit reliable classification of the endings into more than one morphological category. Moreover, the terminals of fusimotor (gamma) and skeletofusimotor (beta) axons on bag1 fibers appeared similar in cross-section. The degree of indentation of axon terminals into the surface of bag1 fibers increased with increasing distance from the spindle equator. However, cross-sectional areas of sole plates and axon terminals were relatively constant regardless of distance from the equator. The subjunctional membranes of both gamma and beta bag1 endings were typically smooth in contour. Bag1 endings differed from those on bag2 and typical chain fibers in having a thicker sole plate, frequently indented axon terminals, and unfolded subjunctional membranes. None of the bag1 endings resembled an extrafusal end plate. These observations indicated that (1) the dynamic (bag1) and static (bag2 and chain) intrafusal systems of the cat spindle are under separate motor control, and (2) the type of intrafusal fiber and the distance of the motor ending from the equator have a greater influence on the form and structure of bag1 endings than do supplying axons.

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A study of motor nerve terminals on cat nuclear bag₁ intrafusal muscle fibers using the ChE staining technique

Cited by 14 publications

References 26 publications

Rat extraocular muscle

Rat extraocular muscle

Form and classification of motor endings in mammalian muscle spindles

Histological study of motor innervation of nuclear bag₁ intrafusal muscle fibers in the cat

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A study of motor nerve terminals on cat nuclear bag1 intrafusal muscle fibers using the ChE staining technique

Cited by 14 publications

References 26 publications

Rat extraocular muscle

Rat extraocular muscle

Form and classification of motor endings in mammalian muscle spindles

Histological study of motor innervation of nuclear bag1 intrafusal muscle fibers in the cat

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A study of motor nerve terminals on cat nuclear bag₁ intrafusal muscle fibers using the ChE staining technique

Histological study of motor innervation of nuclear bag₁ intrafusal muscle fibers in the cat