Abstract
AT the meeting of the Royal Society held on February 10, Sir Joseph Barcroft and D. H. Barron showed a film illustrating the development of movement in the fœtus of the sheep. The development of movement was depicted in respect of: (a) the types of movement which appear at different fœtal ages, and (b) the individuation of certain sorts of purposive movement from a general mass movement. The period of gestation is about 145 days. Up to about 35 days, the fœtus is immobile (type 1). At 35 days it commences to exhibit movements which are always 'jerky' (type 2). At 47–50 days it is almost incessant motion, which is 'sustained' (type 3). After 50 days the fetus becomes quiescent (type 4). The following analysis may be made of these types: If the spinal cord be cut just below the brain at 60 days, without taking the fetus out of the uterus, and the fetus be allowed to continue growing until the cut fibres have degenerated, its body will exhibit jerky movements (type 2), whilst its head is quiescent (type 2). If the central nervous system is transected below the pons, the whole fetus exhibits jerky movements (type 4). If the central nervous system is sectioned above the red nucleus the fetus exhibits sustained movements (type 3). The mechanism for the integration of 'jerky' into 'sustained' movements is in the region of the red nucleus, and the mechanism for the inhibition of movement is preponderantly above that. Later parts of the film showed the development of respiratory movements (especially in relation to somatic movement), the development of progressive movement and the development of 'righting' movements.
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Film illustrating Movement of a Fætus. Nature 141, 322 (1938). https://doi.org/10.1038/141322a0
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DOI: https://doi.org/10.1038/141322a0