close

Вход

Забыли?

вход по аккаунту

?

Variation in human fungiform taste bud densities among regions and subjects.

код для вставкиСкачать
THE ANATOMICAL RECORD 216:474-482 (1986)
Variation in Human Fungiform Taste Bud Densities
Among Regions and Subjects
INGLIS J. MILLER, JR.
Department of Anatomy, Bowman Gray Schoot of Medicine, Wake Forest University,
Winston-Salem, NC 27103
ABSTRACT
Taste sensitivity is known to vary among regions of the tongue and
between subjects. The distribution of taste buds on the human tongue is examined
in this report to determine if interregional and intersubject variation of taste bud
density might account for some of the variation in human taste sensitivity. The
subjects were ten males, aged 22-80 years, who died from acute trauma or a n acute
cardiovascular episode. Specimens were obtained as anatomical gifts or from autopsy. A sample of tissue about 1cm2 was taken from the tongue tip and midlateral
region; frozen sections were prepared for light microscopy; and serial sections were
examined by light microscopy to count the taste buds. The average taste bud (tb)
density on the tongue tip was 116 tblcm2 with a range from 3.6 to 514 among
subjects. The number of gustatory papillae on the tip averaged 24.5 papillaelcm'
with a range from 2.4 to 80. Taste bud density in the midregion averaged 25.2 tbl
cm2 (range: 045.91, and the mean number of gustatory papillae was 8.25/cm2(range:
0-28). The mean number of taste buds per papilla was 3.8 2.2 (s.d.) on the tip and
2.6 5 1.5 (s.d.1 on the midregion. Subjects with the highest taste bud densities on
the tip also had the highest densities in the midregion and the highest number of
taste buds per papilla. Taste bud density was 4.6 times higher on the tip than the
midregion, which probably accounts for some of the regional difference in taste
sensitivity. The difference of more than 2 log units in taste bud density probably
accounts for some differences in taste sensitivity among human subjects.
The regional density and distribution of taste buds has
not been quantified on the human tongue. Taste thresholds are known to vary among different regions of the
tongue (Collings, 1974). Diminished taste sensitivity
among human subjects has been attributed to genetic
factors (Kalmus, 19711, aging (Murphy, 1979; Schiffman
et al., 1979; Grzegorczyk et al., 19791, and disease (Snow,
1983). Taste intensity in normal human subjects is proportional to the number of fungiform papillae which are
stimulated (Smith, 1971), and the number of taste qualities elicited by stimulation of individual fungiform papillae is greater for papillae with multiple taste buds
(Arvidson and Freiberg, 1980).We hypothesize that some
of the variation in taste sensitivity found in human
population may be attributable to differences in the
numerical density or regional distribution of the taste
buds.
Quantification of human fungiform taste buds has
come from excised papillae. Papillae taken from 22 cadaver tongues (Arvidson, 1979) or from 31 living volunteers (Arvidson and Freiberg, 1980) yielded comparable
results. Over half of the papillae contained no taste
buds. About one-fourth of the papillae contained one to
three taste buds, and 10-20% contained four taste buds
or more. From three to 21 papillae were sampled per
subject in the earlier report of Arvidson (1979), and no
taste buds were found in the sample from three subjects.
From 5 to 85% of the excised papillae contained taste
buds among the 22 cadaver subjects. In a study of hu0 1986 ALAN R. LISS, INC.
man taste buds by transmission electron microscopy,
three to five papillae were excised from 11 volunteers;
but taste buds were reported in the samples from only
three subjects (Paran et al., 1970). It is not clear from
excised papillae whether differences in the prevalence
of taste buds among subjects were due to chance in the
sampling of fungiform papillae or whether there is a
significant difference in the number or distribution of
fungiform taste buds among humans.
The distribution of taste buds was studied in two regions (tip vs. midlateral) of the human tongue for a
population of ten male subjects. These two regions were
selected because of documented differences in their taste
thresholds. No information was available on the taste
abilities of the subjects, but all died from acute causes
(trauma or vascular episode) and were presumed to represent a normal gustatory population. The number of
available specimens for this study was limited, so the
population included both Blacks and Whites and a range
in ages of 58 years. In order to avoid the problem of
sampling papillae described above, the entire taste bud
population in the selected region was quantified with
serial microscopy. The objective was to compare the
number of taste buds among regions and among subjects
to determine if there were substantive differences which
could account for variations in human taste sensitivity.
Received June 4,1986; accepted July 22,1986
475
VARIATION IN HUMAN TASTE BUD DENSITIES
Fig. 1. Human cadaver tongue. The photograph (left) is montaged to show fungiform papillae
in focus on the tongue tip and in the middle regions. A millimeter scale is located on the back
of the tongue. The diagram (right) indicates the regions from which samples are taken from the
tongue tip and midregion.
MATERIALS AND METHODS
Observations were made on ten human tongues obtained from anatomical gifts and autopsy specimens by
the Departments of Anatomy and Pathology, Bowman
Gray School of Medicine of Wake Forest University. The
subjects ranged in age from 22 to 80 years at death. All
subjects were males including three Blacks and seven
Caucasians who died of acute trauma or acute cardiovascular episodes.
Tongues were removed from perfused cadavers or obtained fresh from autopsy. All specimens were washed
in tap water and fixed in AAF (ethyl alcohol; acetic
acidformalin) in the refrigerator at 4°C. Fixed tongues
were photographed, and observations were referred to a
schematic drawing of the photograph. A tissue block
about 1cm2 was cut from the tongue tip and midregion,
respectively, for light microscopy. The blocks were
washed in running tap water and dehydrated in 30%
sucrose. The tissue was frozen in O.C.T. Compound
(Miles Scientific), cut a t 20 pm in a cryostat, mounted
on slides, and stained with hematoxylin and eosin. Serial sections were examined and the locations of taste
buds on papillae were measured from the cut edges of
the tissue block. A diagram of the locations of taste buds
was referred to photographs of the tongue to identify the
specific papillae on which taste buds were found.
RESULTS
Figure 1 shows a human cadaver tongue with a diagram of the regions sampled for taste bud density. A
montaged picture is used to show papillae on the tip and
in the posterior regions from different planes of focus.
The area containing fungiform papillae extends rostra1
from the circumvallate papillae to the tongue tip excluding a region along the central midline. The size of the
tongue varied in proportion to the body, and averaged
about 50 cm2 among subjects. Its surface area shrunk
with fixation and dehydration, and fissures became more
prominent. The sampled areas on the tip and midregion
of ten cadaver tongues averaged 1.24 and 1.25 cm2,
respectively.
Examples of fungiform papillae containing taste buds
are shown in Figure 2 (arrows). Papillae with taste buds
(Fig. 2D) varied in structure from the typical “fungiform” or mushroom-shaped type with slender necks
and enlarged heads (Fig. 2B) to inconspicuous bumps
476
I.J. MILLER, JR.
Fig. 2. Photomicrographs of sections from human tongues. A) Arrows indicate taste buds on
a classical fungiform papilla. X 50. B) The same section as in A shows variations in the shape
and height of gustatory papillae (stars). X 5. C) Gustatory papillae which are not of the typical
“fungiform” shape. x 5. D) A human taste bud with a pore at the lingual surface. x 400.
(Fig. 2 C) scarcely elevated from the surrounding epithelial surface. Determination of the proportion of papillae
containing taste buds would require a n arbitrary definition of which papillae without taste buds to include in
the calculation. Variation among subjects in the morphology of papillae, with and without taste buds, requires a separate report. Instead, this report focused on
gustatory papillae, viz. those bearing taste buds.
A sample from the tip region of specimen 25 is shown
in Figure 3. Stars mark the papillae which contained
taste buds, and the diagram indicates the number of
taste buds in each of the papillae. This sample occupied
a n area of 0.84 cm2 with 19 gustatory papillae containing 152 taste buds. Taste buds are most dense along the
margin of the tip, and their papillae are grouped into
clusters. The subject was a 29-year-old white male who
died of acute trauma.
Table 1shows the densities of taste buds and gustatory
papillae among the population of ten subjects. The subject number (column 1) was arbitrarily assigned for ref-
477
VARIATION IN HUMAN TASTE BUD DENSITIES
TABLE 1. Taste bud and gustatory papilla density'
Subject
Tip region
Age/
Tb/
(years) Taste buds/cm2 Papillae/(cm2) pap
16
33
34
7
35
27
2
15
25
26
22
53
22
75
80
56
79
53
29
70
3.6
4.9
18.7
23.2
44.0
74.5
148.5
160.7
170.8
514.0
2.4
3.3
3.7
9.5
26.8
27.3
32.1
38.6
21.4
80.0
Mean
SD
51.5
22.8
116.3
154.4
24.5
23.5
Midregion
Tb/
Taste buds/cm2 Papillae/(cm2) pap
8.0
6.4
22.9
3.0
0
2.0
17.7
8.4
68.7
19.0
24.5
85.9
9.3
1.5
0
2.0
11.3
3.2
17.3
4.8
4.4
28.2
2.5
2.0
0
1.0
1.6
2.7
4.1
4.0
5.6
3.0
3.8
2.2
25.2
29.1
8.2
8.8
2.6
1.5
1.5
1.5
5.0
2.4
1.6
2.7
4.6
4.0
'tb, taste bud; pap, papilla.
Fig. 3.Tip region of the tongue from subject 25. The most anterior
portion lies downward. Stars on the top photo show the locations of
papillae with taste buds. The diagram below shows the number of
taste buds in individual papillae. x 9.
erence. Column 2 contains the age of the subjects at
death. Column 3 was calculated by dividing the number
of taste buds by the surface area of the sample from the
tongue tip, and column 6 has the taste bud density of
the sample from the midregion calculated in the same
way. Subjects are listed in the order of increasing taste
bud density on the tongue tip. The densities of gustatory
papillae from the tip and midregion are shown in col-
umns 4 and 7, respectively. Columns 5 and 8, containing
the average number of taste buds per papilla for the tip
and midregion, respectively, were calculated by dividing
the total number of taste buds by the number of gustatory papillae for each sample.
The density of papillae which contained taste buds on
the samples of tip region (column 4) averaged 24.5 +
23.5 (s.d.)/cm2 among subjects with a range from 2.4 to
80. The tip contained fewer than 5 papillae/cm2 in three
subjects, about 10 papillae/cm2 (9.5) in one subject, between 20 and 40 papillae/cm2 in five subjects, and 80
papillae/cm2 in one subject. Subjects averaged 3.8 2.2
(s.d.1 taste buds/gustatory papilla on the tip (column 5)
with a range from 1.5 to eight. Eight of ten subjects had
papillae with five or more taste buds; four subjects had
papillae with ten or more taste buds; and three subjects
had papillae with 15 taste buds or more. Papillae with
ten or more taste buds were found only on tongue tips
with densities of 148 tbs/cm2 or greater.
Individual papillae contained from one to 18 taste
buds on the tip. Seventy percent of papillae contained
five taste buds or fewer, and the median number of taste
buds per papillae was three. Papillae containing a single
taste bud (72 or 25%) were the most numerous. Twentythree percent of papillae had between six and ten taste
buds, and 11-15 taste buds were found on 5%of papillae.
Seven papillae (2%) had 15 taste buds or more, and five
of these occurred on one specimen (No. 26).
The taste bud density (Table 1) on the tongue tip
averaged 116 per cm2 for the ten subjects. There was a
range from 3.6 to 514 taste buds per unit area (tbs/cm2)
with a standard deviation of 154. Two subjects (16 and
33) had less than 10 tbs/cm2; four specimens (34, 7, 35,
and 27) contained between 10 and 100 tbs/cm2; on three
tongues (2,15, and 25), 148-170 tbs/cm2 were found; and
one tongue (26) had 514 tbs/cm2 on the tip.
The mean number of taste buds per papilla (by subjects) noted above points to differences among subjects.
Two subjects (16 and 33) had less than 5 tbs/cm2 on the
tip, and the papillae contained only one or two taste
buds each. Subject 34 had a low taste bud density but a
higher-than-average number of taste buds per papilla.
Subject 27 had a n average number of gustatory papillae
in the sample but a below-average number of taste buds
478
I.J. MILLER, JR
Fig. 4. Midregion sample from subject 2. The lateral margin of the tongue is in the lower
portion of the photo. Stars indicate papillae with taste buds. Note that stars along the lateral
margin are found on structures which are not typical fungiform papillae. x 7.
per papilla and per cm2. Note that division of the mean
taste bud density (116.3) by the mean number of gustatory papillae (24.5) yields a n average of 4.7 taste buds
per papilla. This quotient is substantially weighted by
subject 26, whose taste bud density and papilla density
were more than 2 standard deviations above the mean
(Table 1). The average of 3.8 taste buddpapilla gives
equal weighting to each subject.
Figure 4 illustrates a tissue sample from the midregion of a 79-year-old white male (subject 2) who died
after a stroke. The region comprised 1.5 cm2 of surface
and contained 26 gustatory papillae with a total of 106
taste buds. The lateral margin of the tongue is located
on the lower part of the figure. A companion diagram
shows the number of taste buds on each papilla. Gustatory papillae differ in size and shape, containing from
one to nine taste buds. The form of structures with taste
buds varies from the classical fungiform shape toward
the midline to small elevations and ridges along the
lateral margin. Taste buds are most abundant near the
margin. Like the example from the tip, gustatory papillae are not distributed evenly across the surface but
appear grouped into clusters.
The midregion samples of the ten subjects contained
from 0 to 28.2 gustatory papillae per cm2 with a mean
of 8.2 & 8.8 (s.d.) (column 7, Table 1).One specimen had
no gustatory papillae in the midregion. Five specimens
had from 1 to 5 papillae/cm2; two samples contained
about 10 papillae/cm2; and the remaining two subjects
ranged from 17.3 to 28.2 papillae/cm2. The mean number of taste buds per papilla in the midregion was 2.6 k
1.5 with a range from zero to 5.0. One subject had no
taste buds in the midregion, and the maximum number
of taste buds per papilla was nine. Three subjects had
papillae with only one or two taste buds. Papillae from
six midregion samples had five or more taste buds per
papilla: one with a maximum of six, two with a maximum of eight, and three with a maximum of nine. Papillae with one taste bud comprised 29% of those in the
midregion, and 64% of papillae had three taste buds or
less. Papillae with five taste buds or more comprised
29.5% of the total in the midregion.
Taste bud density in the midregion averaged 25.2 k
29.1 taste buds/cm2 with a range of 0 to 85.9. Four
subjects had less than 10 taste buds/cm2; four subjects
ranged from 17.7 to 24.5; and two ranged from 68.7 to
85.9. Note that papilla densities for eight of ten subjects
fell below the mean. The highest taste bud densities
resulted from two factors: higher densities of gustatory
papillae and higher numbers of taste buds per papilla
than average. The average number of taste buds in the
midregion from column 8 (2.6 & 1.5) is lower than the
value of 3.05, which is the quotient obtained by dividing
the average taste bud density in the midregion (25.2)by
the mean number of papillae (8.2). The mean of numbers
in column 8 (2.6) gives equal weighting to each subject,
479
VARIATION IN HUMAN TASTE BUD DENSITIES
Human Taste Bud Density
* 2 TIP
f
:I
1
2 HID
1
A
2 3 4 5 b 1 8 9 10 II I2 13 I4 15 I b I 7 I8
TASTE BUDS PER PAPILLA
'I
3
1
2
3
4
5
6
7
8
TASTE BUDS PER PAPILLA
5 HID
5 TIP
Human Gustatory Pap111a Dmslty
I
2 3 4 5 6 7 8 9 10 II I?I3 14 IS Ib I7 I8
TASTE BUD5 PER PAPILLA
P
A
P
I
1
2
3
4
5
6
7
.
~
TASTE BUDS PER PAPILLA
= a TIP
8 HID
L
L
A
E
I
C
n
8
Q
1
2
3 4
S
6
7
8
9 10
( 1 I 1 I3 14 19 I6 I 7 18
TASTE BUD5 PER PAPILLA
1
1
3
4
S
b
7
8
TASTE E M 5 PER PAPILLA
Fig. 5. Plots of the taste bud densities (top) and gustatory papilla
densities (bottom) among subjects. Specimens are listed in the rank
order found in Table 1. Note that the ordinates are plotted on a
logarithmic scale.
Fig. 6. Frequency distributions of taste buds per papilla by region
for three subjects. The speciman numbers are the same as in Figure 5.
while the quotient of 3.05 taste buds/papilla is weighted
by the taste bud densities of subjects 2 and 26.
While the foregoing results have been presented by
regions, Figures 5 and 6 emphasize a comparison of
regions between subjects. The top panel of Figure 5
shows the density of taste buds, and the bottom panel
illustrates the density of gustatory papillae among subjects. Note that the ordinates in Figure 5 are plotted on
a logarithmic scale. Filled symbols represent data from
the tip region, and the unfilled symbols represent the
midregion. Specimens are ordered as in Table 1 according to the density of taste buds on the tongue tip. The
slope of the relationship between specimens and density
has no special significance except to show that there is
a continuous distribution of taste bud densities among
subjects from fewer than five to more than 500. The
density of taste buds in the midregion generally parallels the density of the tip region among subjects; that is,
subjects who had more taste buds on the tip than other
subjects also had more taste buds in the midregion.
There are two notable exceptions. Specimen 1 had the
lowest taste bud density on the tongue tip, but the sev-
enth-highest taste bud density on the midregion. The
midregion of specimen 3 had no taste buds, but the
density of the tongue tip ranked above the two other
subjects.
The bottom panel of Figure 5 shows the relationship
of papilla densities among subjects. The specimens are
ordered in the same manner as Table 1. Note that the
rank orders of papilla densities follow the pattern of
rank orders of taste bud densities. The densities of papillae on the tip divide into two groups of specimens:
Specimens 5-10 had more than 20 papillae per cm2.
Specimens numbered 1-4 had fewer than ten gustatory
papillae per cm2. The densities of papillae on the midregion divided into two partially different groups than
those of the tip: Specimens 2-4, 6, 8, and 9 had fewer
than five gustatory papillae per cm2, while specimens
numbered 1,5, 7, and 10 had nine or more papillae per
unit area.
The distribution of taste buds per papilla is illustrated
in Figure 6 for both tip and midregion in three subjects.
The specimen numbers at the top of each graph are the
same as in Figure 5. Specimen 2 had four gustatory
480
I.J. MILLER, JR
papillae in the sample from the tip. Two papillae each
had one or two taste buds, respectively. The midregion
sample had two papillae with two taste buds each. The
low taste bud density of this subject was due both to a
below-average number of gustatory papillae in each region and a below-average number of taste buds per gustatory papilla. Specimen 5 ranks fifth in taste bud
density on the tip and fifth in taste bud density in the
midregion. The density of gustatory papillae was about
average on the tip and above average in the midregion.
The number of taste buds per papilla was below average
for both regions due to a predominance of papillae with
one or two taste buds. Specimen 8 was above average by
all measures of taste bud distribution on the tip. The
average number of taste buds per papilla (3.98) reflects
the mode of the distribution at two to four taste buds
per papilla. While papillae with ten taste buds or more
accounted for 11% of papillae on the tip, they represented 26.9% of the taste buds. In the midregion, six
papillae contained a total of 24 taste buds. The densities
of papillae and taste buds were below average while the
average number of taste buds per papilla was above
average.
DISCUSSION
The most striking observation from this study is a
difference in taste bud density of 2 log units between
the highest and lowest subjects. This observation probably accounts for some of the disparity in taste sensitivity
among individuals in a human population, There is a n
average 4.6-fold difference in taste bud density on the
tongue tip and on a midregion sample. This difference
contributes to the disparities in regional taste sensitivity which have been reported for the human tongue.
Current results permit a n estimate of the total number
of fungiform taste buds on the human tongue. It is
estimated that the four subjects with the lowest taste
bud densities may have had a n average total of 200
fungiform taste buds per side of the tongue, while the
four subjects with the highest densities may have had
as many as 2,000 fungiform taste buds per side.
Behavioral evidence supports the conclusion that taste
sensitivity is proportional to taste bud density. The intensity of taste sensation elicited from a region of the
tongue tip at a given concentration of stimulus is proportional to the number of fungiform papillae which are
located in the stimulated region (Smith, 1971). Single
fungiform papillae are relatively insensitive to chemical
stimulation (Harper et al., 1966; McChtcheon and Saunders, 1972; Bealer and Smith, 1975; Cardello, 1978,
1979); hence, ensembles of papillae are probably necessary to convey meaningful taste perception. The more
taste buds in a single fungiform papilla, the wider variety of taste sensations which can be elicited by chemical
stimulation of it (Arvidson and Freiberg, 1980). Threshold concentrations for the same stimulus vary among
different regions of the tongue (Shore, 1892; Hanig, 1901;
Collings, 1974), although the slopes of suprathreshold
perceptural intensities are comparable for different regions of the tongue and soft palate (Collings, 1974).
The range of taste bud densities among subjects cannot be accounted for by systematic differences due t o
age, race, or cause of death. By dividing our sample
population in half, the average age of the five subjects
with lowest taste bud density is 50.2 years (s.d. = 27.8),
while the mean age of the five subjects with the highest
taste bud densities is 57.4 years (s.d. = 19.1). Three
Blacks out of ten in the group rank fifth, sixth, and
tenth in increasing order of tip taste bud density, but
this sample is insufficient to determine a trend. Three
of the five subjects with the lowest taste bud densities
died of acute trauma and two died of acute vascular
disorders; three of five of the highest taste bud densities
also died of acute trauma, and two died of acute vascular
conditions. While the state of health just prior to death
is difficult to determine, the prevalence of acute vascular conditions vs. trauma as the cause of death is equally
distributed among the halves of the population with the
highest and lowest taste bud densities, respectively.
There are contrary conclusions about the effects of
aging on the number of taste buds and taste functions
(Mistretta, 1984; Schiffman et al., 1979). Taste thresholds are reportedly increased in older human subjects
(Murphy, 1979; Grezegorczyk et al., 1979) and recognition of foods is lower in elderly subjects than in college
students (Schiffman, 1977). Elderly subjects may experience mild dysgeusia without serious loss of taste sensation intensity (Bartoshuk et al., 1986). Average
numbers of taste buds per circumvallate papilla diminish with aging in adult humans ( h e y et al., 1935; Mochizuki, 1937). The change in foliate taste buds with aging
is equivocal (Mochizuki, 1939),and the average number
of taste buds per fungiform papilla seems not to be
correlated with the age at death (Arvidson, 1979). Minimal changes attributable to aging were observed in taste
bud number in both rats (Mistretta and Baum, 1984)
and rhesus monkeys (Bradley et al., 1985). Mistretta
(1984) concluded that neither anatomical nor physiological changes reported in taste or olfactory receptors appear to account for alterations in food appreciation
reported by elderly human individuals.
A few clinical conditions can be cited in which there is
both a reduction in the taste bud population and a diminution in taste acuity. Familial dysautonomia is a severe congenital disease in which there is a reduction in
taste sensitivity (Smith and Dancis, 1964) as well as an
absence (Smith et al., 1965) or reduction (Moses et al.,
1967) in the number of fungiform papillae and their
taste buds. Curiously, methacholine treatment seems to
enhance taste sensitivity in these patients without apparent change in the absence of taste buds (Henkin and
Kopin, 1964), which prompted speculation by the authors that taste perception can occur in the absence of
taste buds. Patients receiving therapeutic radiation to
the head suffer a reduction in taste acuity, while mice
subjected to similar radiation treatment show a diminution in the number of taste buds in the circumvallate
papilla (Conger and Wells, 1969; Conger, 1973). Sjogren's syndrome includes impairment of salivary secretion, lacrimal gland secretion, and secretion of nasal
mucous glands a s well as impairment of both taste and
smell (Henkin et al., 1972). Taste buds are decreased in
number, and those which persist are abnormal in
appearance.
From our samples of the tip and midregion densities,
a n estimate can be made of the average total number of
human fungiform taste buds. The average density of 25
taste buds per cm2 on the midregion may be applicable
to approximately 10 cm2 on each side for a total of 250
taste buds per side. The average tip region density of
VARIATION IN HUMAN TASTE BUD DENSITIES
116 taste buds per cm2 may apply to about 4 cm2 for a
total of 464 taste buds on each side of the tip. The central
midline region contains few fungiform papillae in 4 em2
per side, and the number of taste buds in this region is
difficult to estimate. Another region which is difficult to
estimate is the area of large fungiform papillae which
lies between the circumvallate papillae and the central
midline. While no systematic study was made of this
region, taste buds were observed on some of these papillae. In total, we estimate a n average of 800 fungiform
taste buds on each side, which is about twice as many
as the estimate of Braus (1940).
Hanig (1901) reported that the tongue is most sensitive to sweet and salt on the tip, sour on the sides, and
bitter on the back. Collings (1974) studied regional taste
sensitivity by threshold determination and by magnitude estimation for a range of concentrations above
threshold. Stimuli were applied by circular filter papers
4 mm in diameter to the tip of the tongue and to a region
2.5 cm posterior on the side. The thresholds were lower
(more sensitive) on the tip for quinine and sucrose than
on the side. The side had a lower threshold for citric acid
than the tip, and the thresholds for NaCl were about the
same on both regions. The slope of taste intensities was
steeper (more sensitive) for quinine on the tip than the
side, but slopes for both regions were not different for
NaCI, sucrose, and citric acid.
The tip contains an average taste bud density 4.6
times greater than the midregion. Taste bud density is
determined by two factors: the number of gustatory papillae in a region and the number of taste buds per
papilla. The tip has about three times as many gustatory papilla per area as the midregion and about 1.5
times as many taste buds per papilla. The same two
factors determine differences among individuals. The
correlation between taste bud density and papilla density is 0.89 for the tip and 0.90 for the midregion. Generally, individuals with more gustatory papillae also
have more taste buds per papilla.
A higher taste bud density on the tip than in the
midregion does not account for the differential sensitivity between bitter and sour stimuli. But since bitter
sensitivity is most acute in the high taste bud density of
the tip, there may be a relationship between relative
thresholds to bitter stimuli and relative taste bud densities among subjects. The genetic predisposition for diminished taste sensitivity to phenyl-thio-carbamide
(PTC) (Kalmus, 1971) applies also to diminished sensitivity for the bitter taste of saccharin and sweetness of
sucrose (Bartoshuk, 1979). These are examples of variable taste sensitivities in a n otherwise healthy population. Arvidson and Freiberg (1980) and Paran et al.
(1970) found variable proportions of fungiform papillae
with taste buds among young, healthy volunteers. If
these samples are indicative of taste bud densities, then
they may reveal differences between healthy individuals as large as those in our cadaver specimens. Relative
taste bud distributions are difficult to estimate from a
small sample of papillae.
In conclusion, we find wide variations in fungiform
taste bud density in the tongues of human cadavers.
These variations may be related to the significant differences in taste sensitivity which are also observed in
human population.
481
ACKNOWLEDGMENTS
We wish to thank Elise Williams, Steve Prough and
Reggie Sellars for their technical assistance. Sarah Graham assisted in the preparation of the manuscript. Posthumous donors of anatomical gifts and their families
make invaluable contributions to this project, to humanity, and to medical science. This work was supported by
NINCDS grant 20101.
LITERATURE CITED
Arey, L., M. Tremaine, and F. Monzingo (1935) The numerical and
topographical relations of taste buds to human circumvallate papillae throughout the life span. Anat. Rec., 64:9-25.
Arvidson, K. (1979) Location and number of taste buds in human
fungiform papillae. J. Dent. Res., 87:435-442.
Arvidson, K., and U. Friberg (1980) Human taste: Response and taste
bud number in fungiform papillae. Science, 209:807-808.
Bartoshuk, L. (1979) Bitter taste of saccharin related to the genetic
ability to taste the bitter substance 6-N-propylthiouracil. Science,
205t934-935.
Bartoshuk, L., B. Rifiin, L.E. Marks, and P. Bars (1986) Taste and
aging. J. Gerontol., 41:51-57.
Bealer, S.,and D. Smith (1975)Multiple sensitivity to chemical stimuli
in single human taste papillae. Physiol. Behav., 14:795-799.
Bradley, R.M., H.M. Stedman, and C.M. Mistretta (1985) Age does not
affect numbers of taste buds and papillae in adult rhesus monkeys.
Anat. Rec., 212:246-249.
Braus, H. (1940) Handbuch der mikroskopischen Anatomie des
Menschen. Vol. IV. J. Springer, Berlin, pp. 492-497.
Cardello, A. (1978) Chemical stimulation of single human fungiform
taste papillae: Sensitivity profiles and locus of stimulation. Sensory
Proc., 2173-190.
Cardello, A. (1979) Taste quality changes as a function of salt concentration in single human taste papillae. Chem. Senses 4:l-13.
Collings, V. (1974) Human taste response as a function of locus of
stimulation on the tongue and soft palate. Percept. Psychophysiol.,
16:169-174.
Conger, A. (1973) Loss and recovery of taste acuity in patients irradiated to the oral cavity. Radiat. Res., 53:338-347.
Conger, A., and M. Wells (1969) Radiation and aging effect on taste
structure and function. Radiat. Res., 37:31-49.
Grezegorczyk, P.B., S.W. Jones, and C.M. Mistretta (1979) Age-related
differences in salt taste acuity. J. Gerontol., 34.834-840.
Hanig, D. (1901) Psychophysik des Geschmacksinnes. Philosophische
Studien, 17.576-622.
Harper, H., J. Jay, and R. Erickson (1966) Chemically evoked sensations from human taste papillae. Physiol. Behav., 1:319-325.
Henkin, R., and L. Kopin (1964) Abnormalities of taste and smell
thresholds in familial dysautonomia: Improvement with methacholine. Life Sci., 3:1319-1325.
Henkin, R., N. Talal, A. Larson, and C. Mattern (1972)Abnormalities
of taste and smell in Sjogren’s syndrome. Ann. Intern. Med., 76:375383.
Kalmus, H. (1971) Genetics of taste In: Handbook of Sensory Physiology: Chemical Senses 2. L.M. Beidler, ed. Springer-Verlag, New
York, pp. 165-179.
McCutcheon, B., and J. Saunders (1972) Human taste papilla stimulation: Stability of quality judgements over time. Science, 175214216.
Mistretta, C.M. (1984) Aging effect on anatomy and neurophysiology
of taste and smell. Gerodontol., 3:131-136.
Mistretta, C.M., and B.J. Baum (1984)Quantitative study of taste buds
in fungiform and circumvallate papillae of young and aged rats. J.
Anat., 138:323-332.
Mochizuki, Y. (1937) An observation of the numerical and topigraphical relation of taste buds to circumvallate papillae of Japanese.
Okajimas Folia Anat. Jpn., 15595-608.
Mochizuki, Y . (1939) Studies of the papilla foliata of Japanese. Okajimas Folia Anat. Jpn., 18t355-369.
Moses, S., Y.Rotem, N. Jagoda, N. Talmor, F. Eichhorn, and S. Levin
(1967) A clinical, genetic and biochemical study of familial dysautonomia in Israel. Isr. J. Med. Sci., 3t358-371.
Murphy, C. (1979) The effect of age on taste sensitivity. In: Special
Senses in Aging: A Current Biological Assessment. S. Han and D.
Coons, eds. Inst. of Gerontol., U. Michigan, Ann Arbor, pp. 21-33.
Paran, N., C. Mattern, and R. Henkin (1970) Ultrastructure of the
482
I.J. MILLER, JR.
taste bud of the human fungiform papilla. Cell Tissue Res., 161rl10.
Schiffman, S. (1977) Food recognition by the elderly. J. Gerontol.,
32r586-592.
Schiffman, S., M. Orlandi, and R.P. Erickson (1979) Changes in taste
and smell with age: Biological aspects. In: Sensory Systems and
Communication in the Elderly. J.M. Ordy and K. Brizzee, eds.
Raven Press, New York, pp. 247-268.
Shore, L. (1892)A contribution to our knowledge of taste sensations. J.
Physiol. (Lond.) 13:191-217.
Smith, A., and J. Dancis (1964)Taste discrimination in familial dysautonomia. Peds, 33:441-443.
Smith, A., A. Farbman, and J. Dancis (1965) Absence of taste-bud
papillae in familial dysautonomia and their mothers. Clin. Res.,
13:336.
Smith, D.V. (1971)Taste intensity as a function of areas and concentration: Differentiation between compounds. J. Exp. Psychol., 87:163171.
Snow, J.B., Jr. (1983) Clinical problems in chemosensory disturbances.
Am. J. Otolaryngol., 4:224-227.
Документ
Категория
Без категории
Просмотров
9
Размер файла
988 Кб
Теги
taste, variation, densities, fungiform, among, regions, bud, human, subjects
1/--страниц
Пожаловаться на содержимое документа