Histobiometrical Study of the Ocular Muscles of Japanese Fetuses. VI. Summary of I.-V. Reports. By Akira Hayashi. From the Department of Anatomy, Keio University, Tokyo. In the I.-V. reports') of this study, I have published observations regarding the number of muscle fibres, the thickness, width and size of the ocular muscles, and the size of muscle fibres in the ocular muscles of Japanese fetuses, comprising of jo male and female fetuses in the 7th-loth fetal month. Now, the interessant findings in these reports shall be summarized and presented here as the sixth report. The thickness, width and size of the ocular muscles, i.e., the short and large diameter and the area of the transverse section in the midst of the belly of the ocular muscles, and the number and size (area of the transverse section) of the muscle fibres in the ocular muscles varies not only with different muscles, but also with different individuals and body-sides to which the muscles belong. The largest and smallest value in these measurements of 140 Ocular muscles. are demonstrated in Table T. The proportion between the maximum and minimum is, as indicated in this table, the highest in the number of muscle fibres, then come the size, thickness and width of muscles and the size of peripheral fine,fibres.2) It is the lowest in the size of axial thick fibres. In the latter three measurements the proportion is almost the same and markedly smaller than in the former three. From this it has been revealed that the variation with the different muscles is in the number of muscle fibres the greatest, and in the size of muscle fibres the smallest. 1) Histobiometrical Study of the Ocular Muscles of Japanese Fetuses. I. Number of Muscle Fibres. Okajimas Fol. anat. jap. Bd. 2o. Heft i. 1941. II. Thickness of the Ocular Muscles. Okajimas Fol. anat. jap. Bd. 24. Heft r. r941. III. Width of the Ocular Muscles. Okajimas Fol. anat. jap. Bd. 2.r. Heft z. 1942. IV. Size of the Ocular Muscles. Okajimas Fol. anat. jap. Bd. 2i. Heft 3. 1942. N. Size of Muscle Fibres. Okajimas Fol. anat. jap. Bd. 2i. Heft 4. 5942. 2) As in the V. report described, the most ocular muscles consist of two kinds of muscle fibres, namely axial thick and peripheral fine fibres.
z86 A. Hayashi, Table The proportion between the highest and lowest value on each body-side lies, as indicated in Table 1, in the number of muscle fibres between 3.05 and 12.44, in the size of muscles between 2.03 and 9.43, in the thickness of muscles between 2.07 and 6.38, in the width of muscles between 1.48 and 5.71, in the size of axial thick fibres between 1.08 and 2.45, and in the size of peripheral fine fibres it varies from 1.07 to 2.12. The average value of this proportion on 20 examined body-sides is the highest in the number of muscle fibres, followed in order by the size, thickness and width of muscles, size of axial thick fibres; it is the lowest in the size of peripheral fine fibres. Therefore, it may be right to say that the variation with different muscles on one body-side is also the greatest in the number of muscle fibres and the smallest in the size of muscle fibres. The correlation coefficient between the same named muscles on both body-sides is the highest in the size of muscles, then come the size of axial thick fibres, thickness of muscles, width of muscles and size of peripheral fine fibres, being the lowest in the number of muscle fibres ; there exists a
Histobiornetrical Study of the Ocular Muscles of Japanese Fetuses. 287 significant difference between the greatest and smallest coefficient (Table 1). The right percentage, i.e., the percentage of value in a right muscle to the sum of the value in the corresponding muscles on both body-sides R R+L ioo), is in the number of muscle fibres in 36 out of 70 muscle pairs greater than 5o.00%, in the thickness of muscles in 38 pairs, in the width of muscles in 30 pairs', in the size of muscles in 37 pairs, in the size of axial thick fibres in 42 pairs and in the size of peripheral fine fibres in z i pairs (Table 1). From this it is apparent that in the width of muscles and the size of peripheral fine fibres, the value in a right muscle is in the majority of cases smaller than that in the left same named muscle of the same fetus. The average value of the right percentage in 70 examined muscle pairs is in the size of muscles the greatest, then come the thickness of muscles, size of axial thick fibres, number of muscle fibres, width of muscles, and the smallest in the size of peripheral fine fibres. Only in the size of peripheral fine fibres it is smaller than 50.00% (Table 1). Between the right and left percentage ( R+L x Ivo therexists no significant difference in the number of muscle fibres, width and size of muscles and size of axial thick fibres, while the thickness of muscles and the size of peripheral fine fibres show a signifi- - cant difference. In the thickness of muscles the right muscles are on the average greater than the left, and in the size of peripheral fine fibres the left muscles are greater than the right. The difference between the right and left percentage ( R-14 x Ioo), R+L which shows the degree of the difference of the various measurements between the same named right and left muscles, compared with the sum of the corresponding measurements in the two same named muscles, is in the width of muscles in 45 out of 70 muscle pairs lower than io.00%, in the size of peripheral fine fibres in 37 pairs, in the thickness and size of museles in 32 pairs, in the number of muscle fibres in 28 pairs and in the size of axial thick fibres in 27 out of 70 muscle pairs (Table Presuming that in a muscle pair with a smaller difference than xo.00% the measurement in the right and left same named muscles resembles each other, it might be said that in the width of muscles and size of peripheral fine fibres the majority of 70 muscle pairs show no marked difference between the right and left muscles. The average value of this difference in 70 examined muscle pairs is, as indicated in Table 1, in the size of muscles the highest, followed in order by number of muscle fibres, size of axial thick fibres, thickness of muscles and size of peripheral fine fibres ; it is the lowest in the width of muscles. It is commonly recognized that symmetrical organs are influenced by the same
. z88 A. Hayashi, hereditary factors and that the difference between the corresponding organs on both sides is due to the influences of the environment. From this and above mentioned data it may be concluded that the degree of the influences of the environment is high in the number of muscle fibres and size of muscles, middle in the thickness of muscles and size of axial thick fibres and low in the width of muscles and size of pecipheral fine fibres. A measurement which show a high correlation coefficient between the same named muscles on both body-sides indicates not always a low difference between the right and left percentage. Although in the number of muscle fibres, which shows the smallest correlation coefficient, one sees a large difference, the size of muscles, which has the largest correlation coefficient, shows also the highest difference. In the width of muscles and size of peripheral fine fibres the correlation coefficient is small in spite of small difference of percentage, and in the thickness of muscles and size of axial thick fibres the correlation coefficient is relatively large, while the difference of percentage is not so small. In my In fetuses, of which male fetuses are in general better nourished and developed than female, the number of muscle fibres, thickness of muscles, width of muscles and size of muscles are in the majority of ocular muscles in the male fetuses greater than in the female, but the size of both axial thick and peripheral fine fibres show completely an opposite relation. All the measurements in ocular muscles show in the examined fetal stage a tendency to increase with age, though the increase does not always go hand in hand with age, and it is not the same in all muscles, and the degree of increase is different with various measurements. When the value of various measurements in an ocular muscle in the 8th-ioth month is represented with a proportion against the value in the corresponding muscle in the 7th month, which is provisionally estimatedas ion, and the average value in seven muscles in each fetal month is calculated, the findings as in Table z are ob- Table a.
Histobiometrical Study of the Ocular Muscles of Japanese Fetuses. 289 tamed. The increase is in the number of muscle fibres of the highest degree, then come the size of muscles, size of axial thick fibres, thickness and width of muscles ; it is of the lowest degree in the size of peripheral fine fibres, as indicated in Table a. I wish to acknowledge my indebtedness to Prof. Dr. S. M o chizuki for his kind incitement. I am also grateful to Assistant-Prof Dr. S. Kato for his kind guidance to this investigation. Literature cited in Report 1.-VI. 1), Bor s, E., Ober das Zahlenverhaltnis zwischen Nerven- und Muskelfaserri. Anat. Anz. Bd. Go. 1926. 2) Haggqvis t, C., Gewebe und Systeme der Muskulatur. v. M011endorffs Handb. d. mikrosk, Anat. d. Menschen. 11/3. 1931. 3) Halba n, J., Dicke der quergestreiften Muskelfasern und ihre' Bedeutung. Anat. H. Bd. 3. 1893. 4) Hoev e, J. v. d. und c. 0. Reoifs. Ober die Wirkung der Augenmuskeln. Arch. Augenhk. Bd. iio. 1937. 5) Kato, T., Uber histologische Untersuchungen der Augenmuskeln von Menschen und Saugetieren. Okajimas Fol. anat. jap. Bd. 16. 1938. 6) Kohashi, Y., Ober histologische Untersuchungen der einzelnen Skelettmuskeln beim Neugeborenen. Okajimas Fol. anat. jap. Bd. i5. 1937. 7), Histologische Untersuchungen der verschiedenen Skelettmuskeln beim Menschen. I. Untersuchung beim Erwachsenen. Okajimas Fol. anat. jap. Bd. 15. 1937. ' 8) Laube r, H.,,Auge. v. M011endorffs Handb. d. mikrosk. Anat. d. Menschen. III/z. 2936. 9) Mayed a, R., Ober die Kaliberverhaltnisse der quergestreiften Muskelfasern. Z. Biol. Bd. 27. 1890. 10) S ch ie ffe rdecke r, P., Eine Eigentiimlichkeit im Bau der Augenmuskeln. Sitzgsber. niederrhein. Ges. Nat. Bonn. 1904. (After Lauber). 11)., Muskeln und Muskelkerne. Leipzig. 2909. i2), Vergleichende Betrachtungen iiber i i6 von mir untersuchte Muskeln. Z. mikrosk.- anat. Forsch. Bd. 9. 2927. I3)_ Schnelle r, J., Anatomische physiojogische Untersuchungen iiber Augenmuskeln Neugeborener. Arch. ophthalm. Bd. 47. 1899. 14) Schwalb e, G. und R. Mayed a, Ober die Kaliberverhaltnisse der quergestreiften Muskelfasern des Menschen. Z. Biol. Bd. 27. 189o. 25) Tergas t, P., Uber das Verhaltnis von Nerven und Muskel. Arch. mikrosk. Anat. Bd. 9. 1873. 16) V olk mann, A. W., Zur Mechanik der Augenmuskeln. Ber. Verh. sachs. Ges. Wiss., Math.-physik. Kl. 1869-70. (After Ho eve urid Roe ifs). 17) V o s s, H., Vergleichende Untersuchungen iiber den Aufteilungsgrader kontraktilen Masse in den Skelettmuskeln. Z. mikrosk.-anat. Forsch. Bd. 38. 19;5. 18) Wohl fa r t, G., Untersuchung aber die Gruppierung von Muskelfasern verschiedener GrOsse und Struktur innerhalb der primaren Muskelfaserbiindel in der Skellettmuskulatur sowie Beobachtungen uber die Innervation dieser Biindel. Z. mikrosk.-anat. Forsch. Bd. 37. 2935. 19) Woollar d, H. H., The innervation of the ocular muscles. J. Anat. Vol. 65. 1931.