口輪筋の成長に対する定量形態学的研究

全自動画像解析装置を応用した正常発育群の定量化

抄録

In order for successful surgical intervention to be performed for restoration of normal oral muscular function to patients suffering from cleft lip, it is necessary to determine the optimal time for operation taking into account the developmental stage of the orbicularis oris muscle. The present investigation is a morphometric approach using an automatic image analyser for generating basic reference data. The orbicularis oris muscle was quantitatively analysed from a total of 120 rabbits, raging from immediately after birth to 180 days old, at which time growth is considered to be almost complete. The results are summarized as follows:
1. By measuring the diameter of the orbicularis oris muscle fibers, visualized as circular profiles, it was established that the immature orbicularis oris muscle at birth underwent rapid growth until day 30 with development being most prominent during the first 15 days. Whether interference with the tissue during this period is appropriate requires discussion.
2. In order to detect morphological changes associated with growth, morphometric estimation by plotting a histogram of the crosssectional area of the oricularis oris muscle was carried out. The results demonstrated that the majority of fibers immediately after birth had areas of less than 20 μ² while 100 days thereafter, very large fibers of 1000 μ² and above were observed. However, even at time points 140, 160 or 180 days, when growth is thought to be completed, some fibers were found to be less than 100 μ² in area, suggesting that their development had been halted sometime during the process. Thus, it appears that growth is not merely a uniform in crement of area with time for all fibers, but rather that a more complicated process is involved, with individual fibers showing both rapid or slow in creases in size.
3. Increase in numbers of fibers associated with growth was obscrved in the first 30 day period wth no further significant increment being apparent thereafter.
4. To facilitate an objecive estimate of alteration in shape associated with the growth of the orbicularis oris muscle, a morphometric coefficient was calculated. The results illustrated that the initially almost circular fibers later become more angular in appearance with increased diameter.
5. Morphometric analysis of the area of nuclei within the fibers revealed very little change and therfroe this parameter would not appear to serve as an appropriate measure of muscle growth.
6. A comparison of the respective growth rates of the orbicularis oris muscle and the total cross-sectional area of the lips demonstrated that, with increase in time, a larger proportion of the total was occupied by the orbicularis oris muscle.