{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,9,10]],"date-time":"2025-09-10T21:36:37Z","timestamp":1757540197452},"reference-count":0,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[1982,10,1]],"date-time":"1982-10-01T00:00:00Z","timestamp":402278400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["The Journal of Physiology"],"published-print":{"date-parts":[[1982,10]]},"abstract":"<jats:p>1. Six muscle spindle poles, five from experiments in which foci of sarcomere convergence had been observed during stimulation of fusimotor axons, were serially sectioned for light and electron microscopy. Every somatic motor terminal was studied in ultrathin sections at several levels.<\/jats:p><jats:p>2. In all six poles static \u03b3 axons, or presumed static \u03b3 axons, supplying the static bag<jats:sub>2<\/jats:sub> fibre and\/or chain fibres had no terminations on the dynamic bag<jats:sub>1<\/jats:sub> fibre. In five poles, the dynamic bag<jats:sub>1<\/jats:sub> fibre was selectively innervated by dynamic \u03b3 or \u03b2 axons save in one case where a dynamic \u03b3 axon also innervated one chain fibre.<\/jats:p><jats:p>3. Seventy\u2010seven motor endings were of four distinct ultrastructural types: \u2018m<jats:sub>a<\/jats:sub> plates\u2019 lay superficially on the surface of static bag<jats:sub>2<\/jats:sub> or chain fibres; \u2018m<jats:sub>b<\/jats:sub> plates\u2019 were deeply indented into dynamic bag<jats:sub>1<\/jats:sub> fibres; in \u2018m<jats:sub>c<\/jats:sub> plates\u2019, found on chain fibres only, the muscle surface was thrown into projecting fingers between which the axon terminals were embedded; one type \u2018m<jats:sub>d<\/jats:sub> plate\u2019 was found, fully indented into a long chain fibre. A few plates of intermediate form (m<jats:sub>ab<\/jats:sub>) were variants of m<jats:sub>a<\/jats:sub> and m<jats:sub>b<\/jats:sub> plates.<\/jats:p><jats:p>4. The muscle membrane beneath both m<jats:sub>a<\/jats:sub> and m<jats:sub>b<\/jats:sub> plates was smooth, or had a few wide, shallow folds; m<jats:sub>c<\/jats:sub> plates usually had wide, shallow subjunctional folds; numerous deep, narrow folds were characteristic of the m<jats:sub>d<\/jats:sub> plate. The length of unmyelinated pre\u2010terminal axon or the number of sole plate nuclei were not useful diagnostic features.<\/jats:p><jats:p>5. Obvious foci of sarcomere convergence in the capsular sleeve region of dynamic bag<jats:sub>1<\/jats:sub> and static bag<jats:sub>2<\/jats:sub> fibres coincided with the location of motor plates. Additional contraction foci were observed in the extracapsular region of dynamic bag<jats:sub>1<\/jats:sub> fibres where there was no motor innervation; contraction occurs principally in the outer half of these fibres. No foci of contraction or motor plates were observed in the extracapsular region of static bag<jats:sub>2<\/jats:sub> fibres; contraction in these fibres is typically mid\u2010polar.<\/jats:p><jats:p>6. In some poles local contraction of chain fibres centred on the location of m<jats:sub>c<\/jats:sub> plates. In others, very localized contraction occurred distal to the sites of m<jats:sub>a<\/jats:sub> plates. Both m<jats:sub>a<\/jats:sub> and m<jats:sub>c<\/jats:sub> plates were never found on the same pole of a chain fibre.<\/jats:p><jats:p>7. Dynamic \u03b3 or \u03b2 axons end in m<jats:sub>b<\/jats:sub> plates, probably equivalent to p<jats:sub>2<\/jats:sub> plates. The concept of distinctly different p<jats:sub>1<\/jats:sub> and p<jats:sub>2<\/jats:sub> plates on dynamic bag<jats:sub>1<\/jats:sub> fibres, supplied by dynamic \u03b2 and \u03b3 axons, respectively, is not supported by ultrastructural evidence.<\/jats:p><jats:p>8. Some static \u03b3 axons end in multiple m<jats:sub>a<\/jats:sub> plates which correspond with \u2018trail endings\u2019, or in single large m<jats:sub>a<\/jats:sub> plates, on static bag<jats:sub>2<\/jats:sub> or chain fibres. The m<jats:sub>c<\/jats:sub> plates are the terminations of other static \u03b3, or occasionally dynamic \u03b3, axons on chain fibres. Static \u03b2 axons probably end in m<jats:sub>d<\/jats:sub> plates on long chain fibres which may correspond with p<jats:sub>1<\/jats:sub> plates.<\/jats:p><jats:p>9. It is proposed that there are two types of static \u03b3 motoneurone, one terminating in m<jats:sub>a<\/jats:sub> plates and the other in m<jats:sub>c<\/jats:sub> plates, possibly directed preferentially towards static bag<jats:sub>2<\/jats:sub> fibres and chain fibres, respectively.<\/jats:p>","DOI":"10.1113\/jphysiol.1982.sp014373","type":"journal-article","created":{"date-parts":[[2014,12,19]],"date-time":"2014-12-19T07:02:28Z","timestamp":1418972548000},"page":"285-309","source":"Crossref","is-referenced-by-count":40,"title":["The ultrastructure of cat fusimotor endings and their relationship to foci of sarcomere convergence in intrafusal fibres"],"prefix":"10.1113","volume":"331","author":[{"given":"E. R.","family":"Arbuthnott","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"K. J.","family":"Ballard","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"I. A.","family":"Boyd","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"M. H.","family":"Gladden","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"F. I.","family":"Sutherland","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[1982,10]]},"container-title":["The Journal of Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1113%2Fjphysiol.1982.sp014373","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/pdf\/10.1113\/jphysiol.1982.sp014373","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,11,5]],"date-time":"2023-11-05T21:20:22Z","timestamp":1699219222000},"score":1,"resource":{"primary":{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/10.1113\/jphysiol.1982.sp014373"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1982,10]]},"references-count":0,"journal-issue":{"issue":"1","published-print":{"date-parts":[[1982,10]]}},"alternative-id":["10.1113\/jphysiol.1982.sp014373"],"URL":"https:\/\/doi.org\/10.1113\/jphysiol.1982.sp014373","archive":["Portico"],"relation":{},"ISSN":["0022-3751","1469-7793"],"issn-type":[{"value":"0022-3751","type":"print"},{"value":"1469-7793","type":"electronic"}],"subject":[],"published":{"date-parts":[[1982,10]]}}}