Number, length and localization of muscle spindles in recti muscles of the eyeball in human fetuses.

Studies were performed on recti muscles of the eyeball, isolated from human fetuses in 14th to 24th week of their development. Number of muscle spindles and their length increased with progressing age of the fetuses. Most numerous muscle spindles were present in the rectus inferior muscle. The spindles were spread along the entire length of the muscle. Somewhat more numerous spindles were present in the half of the muscle belly positioned from the side of original attachment (24th week). Spindles were localized in the peripheral part of the muscle.