The fine structure of the equatorial regions of developing muscle spindles in the rat.
D000818:Animals; D002454:Cell Differentiation; D003593:Cytoplasm; D008928:Mitochondria; D024510:Muscle Development; D009470:Muscle Spindles / Q000166:cytology*; D009132:Muscles / Q000166:cytology / Q000196:embryology; D051381:Rats; D013572:Synaptic Vesicles