Studies on the Papilla Foliata of Japanese. 2. The number of taste buds. By Yoshiro Mochizuki. From the Department of Anatomy Nihon University Dental College, Tokyo, Japan. (Director : Prof. Dr. Y.Izawa.) with 3 text-figures. Introduction. It has already been reported by the present author on the optical studies of the papillae vallatae and the number of taste buds, also the number of papillae foliatae. He proceeded further to investigate the number of taste buds and their locations in the papillae foliatae. L oven (1867) and S chwalbe (1867) report independently their discovery of the taste buds in the mammals. Since then von Wyss (1869), Krause (1870), Ajtai (1872), Ebner (1873), HOnigschmied (1873), Hoffmann (1875), Lustig (1884), Hermann (1885), Tuckerman (1888), Gmelin (1892), Lenhosseck (1893), Stahr (1902, '03, 'o6, 'io.), Heidenhain (1914), Huber u. Eggerth (1917), Okada (1931), Mikami (1931) and Mi yazaki (1933) worked on the same problem. The results of their investigations on the structure and development of the taste buds in papillae foliatae and papillae vallatae are of great value. Nevertheless only a few of these investigators have actually looked into the problem of the number of taste buds. Lustig (1884) reports on the development of taste buds in the papillae foliatae and papillae vallatae of man and the rabbit. In the rabbit, according to his observations, the taste buds are found immediately after birth. The number increases gradually until third week and stops, In man, on the other hand, a small number of taste buds were found in a 7 months old fetus. The number of buds increases gradually. The number in a full grown fetus reaches to that of adult. Tucker man (1888) finds in the
356 Yoshiro Mochizuki, humann fetus that the taste buds in papillae foliatae are first found in the 6 months old fetus. He also describes that the basal cells in the epithelium extends and form the taste buds in the lower layer of the epithelium. According to his investigation he counted i oo taste buds in a single papilla foliata cluster of a 4 months old infant. It is not clear, however, what method he used in this counting. H ei d en h ai n (1914) worked on the papillae foliatae of rabbits and came to the conclusion that the taste buds increase by division. Her mann (18 85) examined rabbits, Ok ada (i931) investigated in man and rats embryologically and stated that the number of taste buds increases after birth. All these results are from embryological studies. They either deal with the increase of the number of taste buds during the period of development of papillae foliatae or the number of taste buds from a small number of human papillae foliatae. No investigator, so far as the writer can ascertain, has ever undertaken to look into the problem concerning the number of taste buds and their location in human papillae foliatae according to different ages. The author therefore took up the problem with special reference to the tongues of Japanese. Material. The larynx was excised from the corpse and the tongues were fixed in i o% formalin or in Zenker's solution. The papillae foliatae clusters were taken out with surrounding tissues from both lateral ridges of the tongues. Two hundred and thirty sets of clusters ranging from new born infants to adults 90 years old. Method. After the materials were washed thoroughly in water, they went through the usual process of dehydration in alcohol. For the purpose of preventing contraction of the tissues, the materials were first immersed in cedar wood oil and then embedded in paraffin. The series of sections were cut parallel to the free surface zoit in thickness, and stained with haematoxylin-eosin. The microscopical observation of these sections shows that the long axis of taste buds, which are spindle shaped, are usually found almost parallel to the cut surface and appear in a few serial sections. The short axis of taste buds varied in the tongue, in the papillae and also according to individual taste buds. The size ranged from zo to 6oia, consequently a single taste bud may be
Studies on the Papilla Foliata of Japanese. 357 found in one section or in four sections of the series. The segments of taste buds which are found in each section were counted and an average taken. This average was used as divisor to figure out the actual number of taste buds. In order to obtain a correct divisor, the sections were projected on tracing paper by means of microscopic projection apparatus and the sections were enlarged 4o times. The tracing papers were piled in order, and according to the outline thus traced an actual number of the taste buds were observed. For instance, a papilla was selected at random from 21-60 years old, and in these papillae there were 3 372 taste buds according to above stated method. The differences of the length of short axis in each bud, however; gave various results in the sections. 33 taste buds were in a single section or a total of 33 sections. 333,, a sections 33 666 3 z8,, y,,, 3,,,,,, )3,, 6 984 33 593,,,, 4,,,,,,,,,, 2 372 13 85,,,,,,,, 5 53,,,,,,,, 425 )3 Thus 3 372 taste buds appear in 10480 sections and average of one bud in 3.1 sections. This average was taken as a divisor, and determined the actual number of taste buds in adults and old age by dividing the total number of pieces of the taste buds in the sections. Likewise the number of taste buds in other age groups was determined by obtaining the average in each group. The average under i year old was ; from 2 zo years was 2.8 ; and that of above 6o years was 3.o. The divisor is small during the period of lactation and youth, it becomes greater at maturity, and shows a slight, decrease in old age. Such variations of the divisors are perhaps due to the fact that in the juvenile period the papillae have not fully developed thus the short axis has not attained its full length ; in old age, on the other hand, the papillae as well as the taste buds may undergo a certain degree of atrophy and their short axis also becomes somewhat shortened. In addition to these parallel sections to the free surface of 230 papillae foliatae clusters, there were a number of other clusters which were cut at right angles to the free surface. Both sections were carefully compared to make our observation accurate in regard to the distribution of the buds. Observation. The taste buts in the papillae foliatae are usually found in the epithelium of papillae facing toward the furrows between the papillae, and are rarely found in the free surface or in the bottom of the furrows. If, however, a
358 Yoshiro Mochizuki, papilla is abnormal the taste buds may be found in the free surface. The central portion of the papillae has more buds than other parts. The taste buds in adults are well developed, and many of them are pear shaped ; in the juvenile period, especially in the new born infant, the buds are long spindle shaped and the basal part is wide and there are some buds which have two taste pores. Such buds are broad spindle shaped and are in the process of divisions. The number of taste buds in the tongue. There were 147 i oo taste buds in T15 tongues according to our method of counting. Tables 1 and a show the number of taste buds and their Table i. The number of taste buds in papillae foliatae Qf the tongues. Table a. The distribution frequency of the number of taste buds in papillae foliatae of the tongues.
Studies on the Papilla Foliata of Japanese. 359 distribution on the tongues. There are striking differences in individuals. The highest number of taste buds in a tongue was 2 957 in a 42 years old woman, and the lowest was 322 in a 75 years old man. The number of 13-400 buds per tongue was most numerous (about '3.9%) and 801-90o came next (about 10.4%) the third place was occupied by izoi-i 300 (about 8.7%). The average was i 279.1. The number of taste buds in the papillae foliatae clusters. The number of taste buds in the papillae foliatae clusters was tabulated in tables 3 and 4. The tongue from a 56 years old woman had i 484 buds, the highest recorded, and a 7 years old man had 143 buds, the lowest in number. About 20.0% of the total findings was from 6o1-700 and stands in the highest percentage. The numbers gradually extend toward maximum Table 3. The number of taste buds in the papillae foliatae clusters. Table 4. The distribution frequency of taste buds in the papillae foliatae clusters.
360 Yoshiro Mochizuki, and minimum, though there are a few cases in which the percentage did not run in order. The average was 639.6 buds. The numer of taste buds in papilla foliata. The examination of individual papilla in the same cluster shows that there are a great difference of the number of taste buds in different papilla. It is already published elsewhere that in a given cluster the papillae are well developed in the middle or back part of the tongue. The furrows between the papillae are deep, and many taste buds are found in the papilla of this region. The results of the examination of i 253 papillae are shown in tables 5 and 6. It is interesting to note that the minimum number of taste buds in a papilla was 13 whereas the maximum was 441. From 5i to TOO buds in one papilla was most predominant (34.0%), IoI-15o was the next (25.3%). The average was 117.4 per papilla. Table 5. The number of taste buds in papilla foliata. Table 6. The distribution frequency of taste buds in papilla foliata.
Studies on the Papilla Foliata of Japanese, 361 The number of taste buds in the papillae on the right and the left hand side of the tongue. The results of comparative studies of the number of taste buds on the right and left side are tabulated in tables 7 and 8. These tables are then graphically reproduced in figure 1. The maximum number of taste buds on the left hand side of the tongue was 408 and the minimum was z8. On the other hand, the right hand side has 441 for a maximum and 13 for a minimum. The numbers between 51-100 buds was the highest distribution frequency (right 33.2%, left 34.8%) lox-15o buds came next (right 26.0% and left 25.1%). The average number in the right was 117.7 buds and that in the left was 117.2 buds. The difference between the right and left was Table 7. The number of taste buds in the papillae foliatae on the right and left hand side of the tongue. Table 8. The distribution frequency of the number of taste buds in the papillae foliatae in the right and left hand side of the tongue.
362 Yoshiro Mochizuki, 0.5±3.8. In some tongues, however, there may be a big difference of the number of taste buds in the right and the left hand side. The tongue from an 18 years old woman had 153 taste buds in the left papilla foliata cluster, and 306 buds in the right. The left hand side had about twice as many buds as the right. Yet when these striking individual cases were averaged with other cases, the differences between the two sides become very small. Figure i. The number of taste buds in the papillae foliatae in the right and left hand side of the tongue. The number of taste buds in the papillae foliatae and sex. The number of taste buds in 705 papillae from 63 male tongues and that of 548 papillae from 5z female tongues are tabulated in tables 9 and 10. Figure a is the graphic reproduction of these two tables. In case of a male, a papilla had 13 taste buds and this was the minimum, and another had 441, Table 9. The number of taste buds in papillae foliatae and sex.
Studies on the Papilla Foliata of Japanese. 363 Table io. The distribution frequency of the taste buds in papillae foliatae and sex. Figure z. Graphic reproduction of the taste buds in papillae foliatae and sex.
364 Yoshiro Mochizuki, the maximum. In case of a female 16 buds was the minimum and 408 was the maximum. From 51-100 buds, both in the male and female, was most frequently found (36.2% in the male, 31.2% in the female), 10I-150 (25.8% in the male, 25.2% in the female) was the next. The average number of the taste buds per papilla was 114.1 in the male and 122.4 in the female. The difference between the sexes was 8.3±3.83. The number of taste buds in papillae foliatae according to age. Out of 115 tongues, there were 37 tongues 448 papillae of the juvenile period, 4o tongues 412 papillae of the maturity period, and 38 tongues 393 papillae of the old age period. Tables i i and 12 and figure 3 are the tabula- Table 1 1. The number of taste buds in the papillae foliatae according to age. Table i 2. The distribution frequency of the number of taste buds in papillae foliatae according to age.
Studies on the Papilla Foliata of Japanese. 365 tions and graphic reproductions of the results of observations. A juvenile tongue had 16 taste buds, the minimum and 369 the maximum. At maturity the minimum was z6 buds and the maximum was 441. In old age, 13 was for the minimum and 408 for the maximum. Through all these age groups 51-Ioo buds was most frequent (38.0% in juvenile, 30.8% in maturity, 32.8% in old age), 101-150 buds came next in the juvenile and maturity periods (33.5 /0 in the former, 22.3% in the latter) and 1-5o was the second place in the old age period (20.6%). Figure 3. Graphic reproduction of the number of taste buds in papillae foliatae according to age. The averages of these 3 groups are as follows : 136.1 was for maturity period, the highest of the groups. The difference between the juvenile period was 28.5+4.56, and that of old age was 27.3+ 5.23. The average of the old age period was 108.8. The difference between the juvenile period was 1.2+4.42. The juvenile period had an average of 107.6. The difference with that of the old age period is slight. These findings seem to show that the taste buds in papillae foliatae are already formed at birth. The number increases as age advances. There is a tendency, however, to decrease in old age.
366 Yoshiro Mochizuki, Discussion. The taste buds in papillae foliatae are found in the middle layer of epithelium in the furrows between the papillae. There is no taste bud in the bottom of the furrow, nor are they found on the top of free surface with rare exceptional cases of abnormal papillae. Ordinarily most of the taste buds are found in the central part of the walls. The taste buds are well developed in adults. They are broad pear shaped. But the taste buds in infants, especially in new born babies, are long spindle shaped. There is a tendency for the taste buds to undergo atrophy in old age, hence the outline of many taste buds becomes indistinct. As for the number of taste buds there is a great difference according to the tongue, the papilla foliata cluster, and the papilla. The average number of taste buds in the papillae foliatae per tongue, however, was i 279.1 and the greatest frequency was x 301-1400 buds in a tongue. The average number of taste buds on one side of the tongue was 639.6. The highest number of cases of the taste buds were 401-500. The average number of taste buds in a papilla was 117.4 and the highest cases were 5 I- loo buds. The total number of taste buds in the right and the left hand side of the tongues also differ greatly. But if the results from a great many materials are compared there is not much difference in the average. The most predominant cases found in a papilla in the right and the left hand side was 5 I-TOO. The number of taste buds per papilla in the different sexes shows that 51-100 was the highest in male and female. The average in men was 114.1 and that of women was '12.4. The difference was extremely small. The number of taste buds in different age groups shows that here too 51-100 buds per papilla was most predominant and 101-150 came next in juveniles and adults. In old age 1-5 o was next. The average number of taste buds in juveniles was 107.6, in adults 136.1, and in old age 108.8. Thus the number of taste buds increases from the juvenile period to maturity, and decreases in old age. The increases of the number of taste buds in adults seems to be the result of the division of the buds and the decrease in old age could be regarded as the atrophy of the buds and disappearance thereof. Mochizuki (1937) has reported the same phenomenon of the taste buds in the circumvallate papillae. Lustig (1884) maintains that the taste buds are found in a 7 months old human fetus, and not earlier. The increase of the buds takes place from
Studies on the Papilla Foliata of Japanese. 367 this period to birth. Tucke rman on the other hand describes that the taste buds are found in a 6 months old human fetus, and in a 4 months old child, he counted 50o taste buds in a single papilla foliata cluster. They do not give the method as to how the taste buds were counted. Their results are quite different from what we found in Japanese tongues. The highest number of taste buds we found was i 484 in a papilla foliata cluster of a 56 years old woman. Hermann (1885), Heidenhain (1914) and Okada (1931) examined rabbits and rats embryologically, and came to the conclusion that the taste buds increase by division of buds. The taste buds in the papillae foliatae of man, according to our observation also increase from infancy to maturity. The author has not been able to find any investigator who has noticed the fact that the taste buds in the papillae foliatae decrease after maturity by atrophy of the taste buds. Our observation proves the fact. Summary. This investigation covered the age from a new born baby to 90 years old. The number of tongues was 115, there were 230 papillae foliatae clusters and i 250 papillae. i. The taste buds in papillae foliatae were found in the epithelium of the papillae which faces the furrow. There were no taste buds on the free surface of papilla or on the bottom of the furrow. 2. In adults, the taste buds are well developed, and broad pear shaped. In youth, they are long spindle shaped. They undergo an atrophy in old age, and the outline of some of the taste buds becomes indistinct. 3. The number of taste buds differs greatly according to the tongue, the papilla foliata cluster and papilla. 4. The maximum number of taste buds per tongue was 2 957 and the minimum was 322. The cases of i 301-1400 taste buds per tongue was most numerous. The average number per tongue was i 279.1. 5. The maximum number of taste buds in a papilla foliata cluster in the right and, the left side of tongue was i 484 and the minimum was 143. The most common cases were of 401-500. The average was 639.6. 6. Among the papillae, a given papilla may contain 13 taste buds, the minimum or 441 taste buds, the maximum. The most frequent cases were between 51 I oo taste buds in a papilla. The average number of the buds per papilla was 117.4. 7. The number of taste buds on the right and left hand side of tongue
368 Yoshiro Mochizuki, varied greatly, but when an average was taken, the difference became very small. The most common occurance of the number of taste buds per papilla was 51 Too in both sides. 8. The number of taste buds according to sex showed that there was no marked difference, in average, between the both sexes. From 5 I-1 o buds per papilla was most common throughout both sexes. 9. The number of taste buds in different age groups shows that from 51 Ioo buds per papilla was most frequent ; the average in youth, however, was 107.6 and that in adults was 136.1 and in old age it was io8.8. This indicates that the number of taste buds increases in adults and decreases in old age. 1o. In general, a great many taste buds were found in well developed papillae which are found in the deep furrows between the papillae at the central location or back part of papilla foliata clusters, and only a few buds were found in the front part where the papillae are in state of trace. The author wishes to express his profound gratitude to Professor Dr. Y. Iz a w a, who suggested the theme of the present investigation and gave kind guidance. The author is also grateful to Dean Dr. K. Satow for his constant encouragement during the tedious period of investigation. He is also greatly indebted to Prof. Dr. R. Hayashi who has helped him in his search for literature. He is thankful to Dr. K. Ta k e u chi who was generous to supply the all necessary materials for the work. The work would never have been completed without such kindness and encouragement. Literature. I) Ajta i, von.: 187z, Ein Beitrag zur Kenntnis der Geschmacksorgane. Ach. f. mikrosk. Anat., Bd. 8. 2) E bne r, V ik tor v on.: 1873, Die acinose Driise der Zunge und ihre Beziehungen zu den Geschmacksorganen. (cited from Arch. f. mikrosk. Anat. Bd. 75.) 3).: 1899, K011ikers Handbuch der Gewebelehre des Menschen, VI. Aufl. III. 4) Gmelin, H.: 1892, Zur Morphologie der Papillae vallata und foliata. Arch. f. mikrosk. Anat., Bd. 40. 5) Graberg. J.: 1898, Beitraege zur Genese des Geschmacksorgans des Menschen. Morphol. Arbeiten., Bd. 8. 6) Hon igschmied, J.: 1873, Beitraege zur mikroskopischen Anatomic caber die Geschmacksorgane der Saugetiere. Zeitschr. 1. wiss. Zoologie, Bd. 23. 7) Hoffmann, A.: 1875, Cber die Verbreitung der Geschmacksknospen beim Menschen. Arch. 1. path. Anat. u. Physiol., Bd. 62. 8) He n, Fr.: 1885, Beitrag zur Entwicklungsgeschichte des Geschmacksorgans beim Kaninchen. Ach. f. mikrosk. Anat., Bd. 24.
Studies on the Papilla Foliata ot Japanese. 309 9) Heidenhain. M.: 1914, Cber die Sinnesfelder und Geschmacksknospen der Papilla foliata des Kaninchens. Arch. f. NIikrosk. Anat., Bd. 85. 10) Flu be r, G. C. and Egge r t h, A. H.: 1917. On the morphogenese of the papillae foliatae of the Rabbit. Anat. Rec., Vol. 13. II) Krause, W.: 1870, Die Nervenendigungen in der Zunge des Menschen. GOttinger gelehrte Nachrichten. 12) K olmer, W., 191o, Lber Strukturen im Epithel der Sinnesorgane, Anat. Anz., Bd. 36. 13) Love n, C.: 1868, Beitraege zur Kenntnis vom Bau der Geschmackswarzchen der Lunge. Arch. 1. mikrosk. Anat., Bd. 4. 14) Lustig.: 1884, Beitraege zur Kenntnis der Entwickelung der Geschmacksknospen. (Cited from Morphol. Arbeiten, Bd. 8.) 15) Lenhosseck, M. v.: 1893, Der feinere Bau und die Nervenendigungen der Geschmacksknospen. Anat. Anz., Bd. 8. 16) Mayer, A. F. J. C.: 1842, Ober die Zunge als Geschmacksorgan. (cited from Arch. f. mikrosk. Anat. Bd. 75.) 17) Mikami, M.: 1931, Ober das Binnennetzapparat der verschiedenen Zellen der Geschmacksknospen. Dainihon Jibiinkokakai-Kaiho, Bd. 36. (in Japanese) 18) Miyazak i, H.: 1933, Pigment in den Geschmackspapillen des Menschen. Jap. J. of med. Sci., 1. Anat. Bd. 3. 19) Mochizuki, Y.: 1937, An observation on the numerical and topographical relations of taste buds to circumvallate papillae of Japanese. Okajimas Folia Anat. Jap., Bd. 15. z Okada, S.: 1931, Uber die Papilla foliata der Maus. Dainihon Jibiinkokakai-kaiho, Bd. 37. (in Japanese) zi).: 1932, Ober die Papilla foliata der Ratte. Aichi Igakkai-Zassi. Bd. 39. (in Japanese) 22) Stahr, H.: 1902, Uber die Papilla foliata beim wilden und beim domestizierten Kaninchen. Anat. Anz., Bd. zi. 23).;.1903, Uber die Ausdehung der Papilla foliata und die Frage einer einseitigen kompensatorischen Hypertrophie im Bereiche des Geschmacksorgans. Arch. f. Entwicklungsmechanik, Bd. 16. 24).: 1903, Zur Aetiologie epithelialer Geschwalste. I. Epithelperlen in den Zungenpapillen des Menschen. Zentralbl. f. allg. Pathol. u. path. Anat., Bd. 14. 25).: 1906, Uber die Zungenpapillen des Breslauer Gorillaweibchens. Jenaische Zeitschrift für Naturwissenschaft, Bd. 41. 26).: 1906, Vergleichende Untersuchungen an den Geschmackspapillen der Orangutan-Zunge. Zeitschr. f. Morph. und Anthropol., Bd. 9. 27) : 1910, Uber gewebliche Umwandlungen an der Zunge des Menschen im Bereich der Papilla foliata. Arch. f. mikrosk. Anat., Bd. 75. 2s) Tuckerman, F.: 1888, The anatomy of the papilla foliata of human infant. Journal of Anat. and Phsiol., Vol. 22. 29) : 1889, On the development of the taste-organs of man. Journ. of Anat. and Physiol., Vol. 23. 3o) V. W y ss, H.: 1869, Cber ein neues Geschmacksorgan auf der Zunge des Kaninchens. Zentralblatt f. d. med. Wiss. No. 31. 31) : 18-0, Die becherfömigen Organe der Zunge. Arch. f. mikrosk. Anat., Bd. 6.