The post-natal development of the inferior dental nerve of the cat.

In most mammals the entire primary dentition is lost during the period of postnatal growth, in the cat between the ages of 7 and 9 months (Mivart, 1881). It has been shown previously (Mohiuddin, 1950) that just before and during this process, morphological changes indicating degeneration, can be demonstrated by silver impregnation methods in the nerve fibres within the pulp of the milk teeth. No changes of this character were seen in the stem fibres in the trunks from which the nerves of the teeth are derived, although it has been shown (Thomas, 1946) that more than half of the fibres in the inferior dental nerve are concerned with the innervation of the teeth and the gums. So far, no quantitative observations have been made on the dental nerve trunks during the growth period, and it is possible that simple inspection might fail to reveal the loss of quite considerable numbers of fibres following the loss of the milk teeth. Whether this occurs or not, one might at least expect that the very marked change which occurs in the peripheral field of distribution would influence the pattern of post-natal development in the dental nerve trunks, and it was for the purpose of investigating this question that the present work was undertaken. The inferior dental nerve of the cat has been examined at various stages from birth to maturity in order to determine the number of axons, the proportion of myelinated axons, and the calibre spectrum of the myelin sheaths, at different ages.

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