1. Allen, E. R., and Pepe, R. A. (1965). Ultrastructure of developing muscle cells in the chick embryo. Am. J. Anat. 116, 115–148.
2. Änggard, L., Bergstroem, R., and Bernhard, C. G. (1961). Analysis of prenatal spinal reflex activity in sheep. Actak Physiol Scand. 53, 128–136.
3. Angulo y Gonzalez, A. W. (1932). The prenatal development of behavior in the albino rat. J. Comp. Neurol. 55, 395–442.
4. Barron, D. H. (1941). The functional development of some mammalian neuro-muscular mechanisms. Biol. Rev. Cambridge Phil. Soc. 16, 1–33.
5. Bodian, D. (1966). Development of fine structure of spinal cord in monkey fetuses. I. The motoneuron neuropil at the time of onset of reflex activity. Bull Johns Hopkins Hosp. 119, 129–149.