[Influence of simulated weightlessness on the morphology of nerve endings of muscle spindle in rat soleus muscle].
OBJECTIVE
To study changes in structure and innervation of soleus muscle spindle in rats induced by simulated weightlessness.


METHODS
Weightlessness was simulated by tail suspension in female rats. The technique of Fawosky's Staining was used to detect the morphology of nerve endings of soleus muscle spindle in 7 d, 14 d, 21 d tail-suspended and control rats.


RESULTS
The intrafusal muscle fibers were regular and nerve endings were intact and clear in the soleus spindles of control rats. No obvious change was observed in muscle spindles of 7 d tail-suspended rats. Intrafusal muscle fibers became irregular, with rough and vague nerve endings in 14 d tail-suspended rats. The distinct retrograde change of muscle spindles and nerve endings were observed in 21 d tail-suspended rats. Degeneration and rupture were found in nerve endings, which made it unclear and pale in staining.


CONCLUSIONS
Simulated weightlessness could induce time-related changes in structure and innervation of soleus muscle spindle in rats.
Tang
Bin
B
Department of Physiology, Xi'an Jiaotong University, Xi'an, China.
Fan
Xiao-li
XL
Wu
Su-di
SD
Li
Ming
M
D000818:Animals; D005260:Female; D019417:Hindlimb Suspension; D009470:Muscle Spindles / Q000033:anatomy & histology* / Q000473:pathology* / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation* / Q000473:pathology / Q000502:physiology; D009411:Nerve Endings / Q000033:anatomy & histology* / Q000473:pathology / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D018474:Weightlessness Simulation