Histochemical characteristics of the masseter and temporalis muscles of the rhesus monkey (Macaca mulatta)

Authors

  • Leo C. Maxwell,

    1. Department of Physiology and the center for Human Growth and Development. The Univeristy of Michigan, Ann Arbor, Michigan 48109
    2. Center for Human Growth and Development. The Univeristy of Michigan, Ann Arbor, Michigan 48109
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  • David S. Carlson,

    1. Department of Anthropology and the center for Human Growth and Development. The Univeristy of Michigan, Ann Arbor, Michigan 48109
    2. Department of Anatomy and the center for Human Growth and Development. The Univeristy of Michigan, Ann Arbor, Michigan 48109
    3. Center for Human Growth and Development. The Univeristy of Michigan, Ann Arbor, Michigan 48109
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  • James A. McNamara Jr.,

    1. Department of Anatomy and the center for Human Growth and Development. The Univeristy of Michigan, Ann Arbor, Michigan 48109
    2. Center for Human Growth and Development. The Univeristy of Michigan, Ann Arbor, Michigan 48109
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  • John A. Faulkner

    1. Department of Physiology and the center for Human Growth and Development. The Univeristy of Michigan, Ann Arbor, Michigan 48109
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  • This research was supported by United States Public Health Service Grant No. DE 04227 and by Contact No. DE 52478 from the National Institute of Dental Research. The National Institute of Health.

Abstract

The histochemical characteristics, cross-sectional area and capillary of the skeletal muscle fibers of the anterior and posterior regions of the superficial masseter and the temporalis muscles are described for juvnile and adult rhesus monkeys of both sexes. Slow twitch fatigue resistant (S), fast twitch fatigue resistant (FR) and fast twitch fatigable (FF) fibers were found in varying proportions throughout the muscles; however some fibers with an intermediate myofibrillar ATPase activity were observed in the anterior masseter. No significant differences for any of the variables were found between male and female juveniles for a specific muscle sample site. However, consideable variation was found between juvenile and adult and between adult male and female monkeys in the percentages of different fiber types and the cross-sectional area of fibers in specific regions of the superficial masseter and temporalis muscles. We conclude from these observations that significant differences in funtion exist both within and between the different masticatory muscles of rhesus monkeys. Functional differences may result from the pronounced sexual dimorphism evident in the dentofacial complex of rhesusmonkey.

Ancillary