The distribution of fungiform papillae and taste buds on the human tongue

Endocrinology of Taste with Aging

Taste is one of our five primary senses, and taste impairment has been shown to increase with aging. The ability to taste allows us to enjoy the food we eat and to avoid foods that are potentially spoiled or poisonous. Recent advances in our understanding of the molecular mechanisms of taste receptor cells located within taste buds help us decipher how taste works. The discoveries of "classic" endocrine hormones in taste receptor cells point toward taste buds being actual endocrine organs. A better understanding of how taste works may help in reversing taste impairment associated with aging.

The sense of taste: Development, regeneration, and dysfunction

Gustation or the sense of taste is a primary sense, which functions as a gatekeeper for substances that enter the body. Animals, including humans, ingest foods that contain appetitive taste stimuli, including those that have sweet, moderately salty and umami (glutamate) components, and tend to avoid bitter-tasting items, as many bitter compounds are toxic. Taste is mediated by clusters of heterogeneous taste receptors cells (TRCs) organized as taste buds on the tongue, and these convey taste information from the oral cavity to higher order brain centers via the gustatory sensory neurons of the seventh and ninth cranial ganglia. One remarkable aspect of taste is that taste perception is mostly uninterrupted throughout life yet TRCs within buds are constantly renewed; every 1-2 months all taste cells have been steadily replaced. In the past decades we have learned a substantial amount about the cellular and molecular regulation of taste bud cell renewal, and how taste buds are initially established during embryogenesis. Here I review more recent findings pertaining to taste development and regeneration, as well as discuss potential mechanisms underlying taste dysfunction that often occurs with disease or its treatment. This article is categorized under: Infectious Diseases > Stem Cells and Development Cancer > Stem Cells and Development Neurological Diseases > Stem Cells and Development.

Three-dimensional characteristic of fungiform papillae and its taste buds in European bison (Bison bonasus), cattle (Bos taurus), and Bison bonasus hybrid

Background

Our recent macro- and scanning electron microscopic study of tongue conducted on domesticated cattle, wild living European bison, and Bison bonasus hybrid revealed various spatial arrangement and number of gustatory and mechanical papillae between parental species and their hybrid. Furthermore, scanning electron microscopy analysis of gustatory papillae indicated the variable distribution of fungiform papillae (Fu) over the surface of the tongue, which could be significant in differentiated taste perception during feeding in studied wild living and domesticated husbandry ruminants. To specify the detailed microstructure of Fu papillae with connective tissue cores (CTC) and intraepithelial taste buds system, the first time the three-dimensional computer-aided analysis of serial histoslides resulted in the rendering of 3D reconstructions of Fu papillae.

Results

The comparative analysis of 3D models Fu papillae conducted in six areas of lingual mucosa of each tongue revealed information about, microstructural diversity of Fu papillae in studied ruminants. The estimation of number and density of Fu papillae on tongues, rate of protrusion of papillae over mucosa, and a number of taste buds per papilla allowed to state the ventral surface of the lingual apex and posterolateral surfaces of the lingual torus as regions important in taste perception, as in the preselection of taken food, as well in the analysis of food during rumination, respectively. On the 3D models were observed three structural types of CTC of different distribution on the tongue in studied species. The quantitative data of the number of taste buds on Fu papillae have regional functional differences in the taste system important in feeding and veterinary practice. Moreover, our analysis determined specific features in examined hybrid and showed similarities of some studied features with cattle, i.e., maternal species.

Conclusions

The 3D reconstruction method used for the first time in the field of study of the lingual papillae and taste buds system can be considered as an innovative and effective tool in assessing of the microstructures of Fu papillae, and it could be suitable for further studies of taste system structures in normal and pathological condition.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03111-5.

Longitudinal trajectories and determinants of human fungiform papillae density

Tongue fungiform papillae contain taste buds crucial for taste and hormone-producing taste receptor cells; therefore, they may be considered as endocrine organs and have important age-associated physiological implications. We examine the cross-sectional and longitudinal trajectories of fungiform papillae density in 1084 participants from the Baltimore Longitudinal Study of Aging using linear regression models and mixed effects models. At baseline, the mean age was 67.86 ± 14.20 years, with a mean follow-up time among those with repeat visits of 4.24 ± 1.70 years. Women (53%) were younger (66.85 ± 13.78 vs. 69.04 ± 14.61 years, p < 0.001) and had a higher fungiform papillae density than men (16.14 ± 9.54 vs. 13.77 ± 8.61 papillae/cm², p < 0.001). Whites (67%) had a lower fungiform papillae density than non-Whites after adjusting for age and sex. Factors cross-sectionally associated with a lower fungiform papillae density included a higher waist-hip ratio (β = −8.525, p = 0.029), current smoking status (β = −5.133, p = 0.014), and alcohol use within the past 12 months (β = −1.571, p = 0.025). Longitudinally, fungiform papillae density decreased linearly with follow-up time (β = −0.646, p < 0.001). The rate of decline was not affected by sex, race, BMI, waist-hip ratio, smoking, or alcohol use. The longitudinal decline of fungiform papillae density over time needs to be explored further in order to identify other possible age-associated physiological determinants.

Geographic tongue as a reaction-diffusion system

Geographic tongue or benign migratory glossitis is a condition of an unknown cause characterized by chronic lesions that slowly migrate across the surface of the tongue. The condition's characteristic wavefronts suggest that it can be modeled as a reaction-diffusion system. Here, we present a model for geographic tongue pattern evolution using reaction-diffusion equations applied to portions of spheroids and paraboloids that approximate a tongue shape. We demonstrate that the observed patterns of geographic tongue lesions can be explained by propagating reaction-diffusion waves on these variably curved surfaces.

Taste of time: A porous-medium model for human tongue surface with implications for early taste perception

Most sensory systems are remarkable in their temporal precision, reflected in such phrases as “a flash of light” or “a twig snap”. Yet taste is complicated by the transport processes of stimuli through the papilla matrix to reach taste receptors, processes that are poorly understood. We computationally modeled the surface of the human tongue as a microfiber porous medium and found that time-concentration profiles within the papilla zone rise with significant delay that well match experimental ratings of perceived taste intensity to a range of sweet and salty stimuli for both rapid pulses and longer sip-and-hold exposures. Diffusivity of these taste stimuli, determined mostly by molecular size, correlates greatly with time and slope to reach peak intensity: smaller molecular size may lead to quicker taste perception. Our study demonstrates the novelty of modeling the human tongue as a porous material to drastically simplify computational approaches and that peripheral transport processes may significantly affect the temporal profile of taste perception, at least to sweet and salty compounds.

Taste perception is an important gateway for food selection, food intake, energy and nutrition balance–as world is facing epidemic of obesity and diabetes. Information conveyed via the taste system provide crucial behavior choices, e.g. in identifying edible and nutritious food source, driving hedonic evaluation and craving, as well as avoiding poisonous substances. Thus, the interest to understand early taste responses is important, not only for basic science, but also for clinical and public health applications.

Taste Buds and Neuronal Markers in Patients with Chronic Renal Failure

Objective

To study the number of taste buds and, with the use of specific markers for peripheral nervous tissue, to study the neuronal pattern in taste buds from 36 patients with chronic renal failure (CRF), 19 renal transplant recipients, and 40 healthy subjects. Of the patients with CRF, 17 patients had not started dialysis, 12 patients were on peritoneal dialysis, and 7 patients were on hemodialysis.

Design

From all subjects, two or three fungiform papillae were collected from the anterior part of the tongue. Cryostat sections were cut and inspected under light microscopy to determine the presence of taste buds. The sections were subsequently incubated with primary rabbit antibodies against protein gene product 9.5, substance P, and nerve growth factor receptor.

Results

Using these antibodies, no differences between the groups were observed. However, patients with CRF had fewer taste buds than control subjects.

Conclusion

No immunohistochemical differences were observed between patients with CRF and healthy controls. However, patients with CRF had significantly fewer fungiform taste buds, suggesting an important factor contributing to the well-known impairment of taste acuity in this patient group.

Bitter Taste Perception of the Human Tongue Mediated by Quinine and Caffeine Impregnated Taste Strips

Objectives:

Tests for gustatory function have become increasingly important in diagnosis and treatment of patients with taste disorders. While caffeine and quinine hydrochloride solutions have been used for global testing of bitter perception, only quinine has been used to test regional bitter perception by means of taste strips. The aim of the present study was to validate caffeine impregnated taste strips as an alternative to quinine taste strips for assessment of regional bitter perception.

Methods:

A total of 46 healthy volunteers (mean age/range, 23/19-27 years) were included in this study. Quinine and caffeine impregnated taste strips were pairwise presented at different parts of the tongue. Perceived intensity and hedonic dislike were evaluated using labeled magnitude scales. Additionally, gustatory function was assessed using the taste strips test and overall sense of taste was rated using visual analog scales.

Results:

Assessment of gustatory function demonstrated scores within the normogeusic range in most included subjects (mean/SD, 13.1/2.5). Notably, equally concentrated quinine and caffeine impregnated taste strips placed on different regions of the tongue did not lead to significant differences in perceived intensity or hedonic dislike, whereas quinine and caffeine impregnated taste strips of different concentrations placed on the same region on the tongue led to significant differences of perceived intensity and hedonic dislike. Furthermore, no correlation was found between self-assessment of gustatory function and taste strips scores.

Conclusion:

Caffeine seems to be a valid bitter compound for regional testing using taste strips and may be used alternatively to quinine.

Impact of Fungiform Papillae Count on Taste Perception and Different Methods of Taste Assessment and their Clinical Applications: A comprehensive review

Fungiform papillae are raised lingual structures which contain taste buds and thus play an important role in taste perception. These structures vary in number due to their relative sensitivity to a range of systemic and local factors which affect the dorsum of the tongue. Taste sensation can be measured using both chemical and electrical methods; however, the number of fungiform papillae has a direct effect on chemogustometric and electrogustometric values during evaluation. This review provides a general overview of fungiform papillae, their quantification methods and the various factors which may affect these structures. In addition, numerous methods of recording taste sensation and their clinical applications are highlighted.

An automated method to detect and quantify fungiform papillae in the human tongue: Validation and relationship to phenotypical differences in taste perception

Determination of the number of fungiform papillae (FP) on the human tongue is an important measure that has frequently been associated with individual differences in oral perception, including taste sensitivity. At present, there is no standardised method consistently used to identify the number of FP, and primarily scientists manually count papillae over a small region(s) of the anterior tip of a stained tongue. In this study, a rapid automated method was developed to quantify the number of FP across the anterior 2 cm of an unstained tongue from high resolution digital images. In 60 participants, the automated method was validated against traditional manual counting, and then used to assess the relationship between the number of FP and taste phenotype (both 6-n-propylthiouracil (PROP) and Thermal Taster Status). FP count on the anterior 2 cm of the tongue was found to correlate significantly with PROP taster status. PROP supertasters (PSTs) had a significantly higher FP count compared with PROP non-tasters (PNTs). Conversely, the common approach used to determine the number of FP in a small 6 mm diameter circle on the anterior tongue tip, did not show a significant correlation irrespective of whether it was determined via automated or manual counting. The regional distribution of FP was assessed across PROP taster status groups. PSTs had a significantly higher FP count within the first centimetre of the anterior tongue compared with the PNT and PROP medium-tasters (PMT), with no significant difference in the second centimetre. No significant relationship was found with Thermal Taster Status and FP count, or interaction with PROP taster status groups, supporting previous evidence suggesting these phenomena are independent. The automated method is a valuable tool, enabling reliable quantification of FP over the anterior 2 cm surface of the tongue, and overcomes subjective discrepancies in manual counting.

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Automatic, rapid quantification of FP across the anterior 2 cm of the tongue

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FP count in small tongue tip areas does not reliably correlate reliably with PROP status.

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Number of FP across the anterior 2 cm of the tongue correlates with PROP status.

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No relationship identified between the number of FP and thermal taster status.

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PROP and thermal taste are independent phenomena.

Comparison of Taste Threshold in Smokers and Non-Smokers Using Electrogustometry and Fungiform Papillae Count: A Case Control Study

INTRODUCTION

Smoking in long term is not only responsible for cancerous changes but is also one of the reasons of altered taste sensation in smokers. These taste changes are hypothesized to be due to reduction in density of fungiform papillae on the dorsum of the tongue.

AIM

The aim of this study was to assess the relationship between fungiform papillae count, blood Red Cell Distribution Width (RDW) and electrogustometric thresholds in smokers and non-smokers.

MATERIALS AND METHODS

Fungiform papillae count was assessed using digital photography and imaging software while electrogustometric thresholds were assessed using modified Transcutaneous Electric Nerve Stimulation (TENS) machine in 30 smokers and 30 non-smokers. The subjects also underwent RDW evaluation. The data collected was analyzed using Pearson's correlation coefficient.

RESULTS

Fungiform papillae counts in smokers were less than those of non-smokers and an inverse relationship was detected between smoking and fungiform papillae count. Electrogustometric thresholds were more in smokers than non-smokers and showed direct relationship with smoking. RDW was significantly more in smokers compared to non-smokers. An inverse relationship was observed between fungiform papillae count and RDW.

CONCLUSION

Our results suggest that smokers have a high taste threshold because of decrease in the number of fungiform papillae on the tongue and RDW values do show an inverse relationship with fungiform papillae density which depicts subclinical nutritional deficiency bringing atrophic changes in tongue.

Denver Papillae Protocol for Objective Analysis of Fungiform Papillae

The goal of the Denver Papillae Protocol is to use a dichotomous key to define and prioritize the characteristics of fungiform papillae (FP) to ensure consistent scoring between scorers. This protocol builds off of a need that has arisen from the last two decades of taste research using FP as a proxy for taste pore density. FP density has historically been analyzed using Miller & Reedy’s 1990 characterizations of their morphology: round, stained lighter, large, and elevated. In this work, the authors forewarned that stricter definitions of FP morphology needed to be outlined. Despite this call to action, follow up literature has been scarce, with most studies continuing to cite Miller & Reedy’s original work. Consequently, FP density reports have been highly variable and, combined with small sample sizes, may contribute to the discrepant conclusions on the role of FP in taste sensitivity. The Genetics of Taste Lab explored this apparent inconsistency in counting and found that scorers were individually prioritizing the importance of these characteristics differently and had no guidance for when a papilla had some, but not all, of the reported qualities of FP. The result of this subjectivity is highly variable FP counts of the same tongue image. The Denver Papillae Protocol has been developed to remedy this consequence through use of a dichotomous key that further defines and prioritizes the importance of the characteristics put forth by Miller & Reedy. The proposed method could help create a standard way to quantify FP for researchers in the field of taste and nutritional studies.

Pre-treatment with amifostine protects against cyclophosphamide-induced disruption of taste in mice

Cyclophosphamide (CYP), a commonly prescribed chemotherapy drug, has multiple adverse side effects including alteration of taste. The effects on taste are a cause of concern for patients as changes in taste are often associated with loss of appetite, malnutrition, poor recovery and reduced quality of life. Amifostine is a cytoprotective agent that was previously shown to be effective in preventing chemotherapy-induced mucositis and nephrotoxicity. Here we determined its ability to protect against chemotherapy-induced damage to taste buds using a mouse model of CYP injury. We conducted detection threshold tests to measure changes in sucrose taste sensitivity and found that administration of amifostine 30 mins prior to CYP injection protected against CYP-induced loss in taste sensitivity. Morphological studies showed that pre-treatment with amifostine prevented CYP-induced reduction in the number of fungiform taste papillae and increased the number of taste buds. Immunohistochemical assays for markers of the cell cycle showed that amifostine administration prevented CYP-induced inhibition of cell proliferation and also protected against loss of mature taste cells after CYP exposure. Our results indicate that treatment of cancer patients with amifostine prior to chemotherapy may improve their sensitivity for taste stimuli and protect the taste system from the detrimental effects of chemotherapy.

Age-related changes in electrogustometry thresholds, tongue tip vascularization, density, and form of the fungiform papillae in humans

The aim of the study was to investigate age-related changes in electrogustometry (EGM) thresholds, in morphology and density of the fungiform papillae (fPap) and in vessels' shape and density at the tip of the human tongue.In 156 nonsmokers (74 males, 82 females; age range: 10-80 years), divided in age groups, EGM thresholds at the chorda tympani area, at the soft palate area, and at the area of the vallate papillae were recorded bilaterally. Morphology and density of the fPap and blood vessels' density and morphology at the tip of the tongue were examined using contact endoscopy (CE). EGM thresholds at the chorda tympani area were significantly higher in both men and women ←60 years of age than in younger individuals. At the soft-palatine area, EGM thresholds were significantly higher in men aged 20-29 years and ←60 years compared with men of other age groups. In women older than 50 years, thresholds at all 3 areas were significantly higher than in the younger age groups. No significant differences in EGM thresholds between the two sexes at all locations tested were detected. The density of fPap decreased significantly in men aged >50 years and in women aged >60 years compared with younger individuals. Vascular density decreased significantly and vascular morphology worsened at the tip of the tongue in subjects older than 60 years of age compared with younger subjects. The study showed statistically significant differences in EGM thresholds between the right and the left side of the tongue and between the two sexes. Aging is associated with a progressive increase in EGM thresholds. Density of fPap plays an important role for taste acuity in females aged >60 years and males aged ←50 years. Morphology of fPap and vessels' density and morphology at the tip of the tongue, as tested by CE, emerge as factors influencing taste function in subjects of both sexes aged >60 years.

Comparison of two doses of breast milk and sucrose during neonatal heel prick

BACKGROUND

The aim of the present study was to test analgesic effects of double- versus single-dose breast milk and compare this effect with efficacy of double- versus single-dose sucrose in a group of healthy term newborns during heel prick blood sampling.

METHODS

Healthy newborns (n= 142) were consecutively allocated to one of the six groups: group 1, single-dose breast milk; group 2, single-dose sterile water; group 3, single-dose 12.5% sucrose; group 4, two doses breast milk; group 5, two doses sterile water; and group 6, two doses 12.5% sucrose before the heel prick. The medians for crying time and the pain scores according to the neonatal facial coding system were recorded.

RESULTS

Crying times were 117 s, 126 s, 82 s, 128 s, 117 s, and 95 s in groups 1-6, respectively (P= 0.053). The mean pain scores were 4.60, 5.82, 3.91, 4.94, 5, and 4.05 in groups 1-6, respectively (P= 0.068). There was a significant difference between the groups for mean pain scores at 1 min and 3 min. There was a significant difference between the single-dose sucrose group and single-dose sterile water group at 1 min (P= 0.002). The babies in the sucrose group were active awake, whereas the ones in the breast milk group were asleep before heel prick.

CONCLUSION

Two doses of sucrose solution were not superior to single-dose sucrose. Neither single nor double doses of breast milk were effective in relieving pain in neonates. Two milliliters breast milk does not reduce response to pain during minor painful procedures in term neonates even when two doses have been given. Further studies are needed.

Change of the human taste bud volume over time

OBJECTIVE

The specific aim of this study is to measure the taste volume in healthy human subjects over a 2.5-month period and to demonstrate morphological changes of the peripheral taste organs.

MATERIAL AND METHODS

Eighteen human taste buds in four fungiform papillae (fPap) were examined over a 10-week period. The fungiform papillae investigated were selected based on the form of the papillae or the arrangement of surface taste pores. Measurements were performed over 10 consecutive weeks, with five scans in a day once a week. The following parameters were measured: height and diameter of the taste bud, diameter of the fungiform papilla and diameter of the taste pore.

RESULTS

The findings of this exploratory study indicated that (1) taste bud volumes changed over a 10-week period, (2) the interval between two volume maxima within the 10-week period was 3-5 weeks, and (3) the diameter of the fPap did not correlate with the volume of a single taste bud or with the volume of all taste buds in the fPap within the 10-week period.

CONCLUSIONS

This exploratory in vivo study revealed changes in taste bud volumes in healthy humans with age-related gustatory sensitivity. These findings need to be considered when studying the effect of denervation of fungiform papillae in vivo using confocal microscopy.

Cracking taste codes by tapping into sensory neuron impulse traffic

Insights into the biological basis for mammalian taste quality coding began with electrophysiological recordings from "taste" nerves and this technique continues to produce essential information today. Chorda tympani (geniculate ganglion) neurons, which are particularly involved in taste quality discrimination, are specialists or generalists. Specialists respond to stimuli characterized by a single taste quality as defined by behavioral cross-generalization in conditioned taste tests. Generalists respond to electrolytes that elicit multiple aversive qualities. Na(+)-salt (N) specialists in rodents and sweet-stimulus (S) specialists in multiple orders of mammals are well characterized. Specialists are associated with species' nutritional needs and their activation is known to be malleable by internal physiological conditions and contaminated external caloric sources. S specialists, associated with the heterodimeric G-protein coupled receptor T1R, and N specialists, associated with the epithelial sodium channel ENaC, are consistent with labeled line coding from taste bud to afferent neuron. Yet, S-specialist neurons and behavior are less specific than T1R2-3 in encompassing glutamate and E generalist neurons are much less specific than a candidate, PDK TRP channel, sour receptor in encompassing salts and bitter stimuli. Specialist labeled lines for nutrients and generalist patterns for aversive electrolytes may be transmitting taste information to the brain side by side. However, specific roles of generalists in taste quality coding may be resolved by selecting stimuli and stimulus levels found in natural situations. T2Rs, participating in reflexes via the glossopharynygeal nerve, became highly diversified in mammalian phylogenesis as they evolved to deal with dangerous substances within specific environmental niches. Establishing the information afferent neurons traffic to the brain about natural taste stimuli imbedded in dynamic complex mixtures will ultimately "crack taste codes."

Gustatory impairment in patients undergoing head and neck irradiation

OBJECTIVES

To determine whether radiation alters taste function and structure.

RESEARCH DESIGN

Prospective, longitudinal study.

METHODOLOGY

Testing prior to starting radiation, and 2 weeks, 2 months, and 6 months after completing radiation.

RESULTS

Relative to controls, patients had lower taste identification test scores for bitter, salty, and sour tastes. Sour taste also showed a significant group-by-time interaction (P = .03). Taste pores were decreased in the irradiated group, with a significant group-by-time interaction (P = .03).

CONCLUSION

Head and neck cancer patients have decreased taste function, and radiation adversely affected sour taste and taste pores.

Regional differences in taste bud distribution and alpha-gustducin expression patterns in the mouse fungiform papilla

The regional differences between distribution patterns and alpha-gustducin expression patterns of the fungiform (FF) taste buds were investigated in the adult mouse, using hematoxylin-eosin staining and immunofluorescence histochemistry on the most anterior region of the tongue (the first millimeter) through the intermediate region of the tongue (the last 1-4 mm). Paraffin sections were prepared from the tip to posterior regions (anterior and intermediate region containing the FF taste buds) of the adult mouse tongue. Results indicate that there were significant regional differences in size and density of taste buds, the cell counts of the single taste bud, and the alpha-gustducin-immunoreactive taste buds between the 2 regions. The taste bud had a characteristic onion-like appearance, and the alpha-gustducin-immunoreactive cell was spindle shaped with elongated processes extending from the base to the pore of the taste buds. These results provide a detailed insight to better understand regional descriptions of mouse taste bud density and size and alpha-gustducin expression with the mouse model.

Effect of foremilk and hindmilk on simple procedural pain in newborns

BACKGROUND

Infants are exposed to painful stimuli during routine medical care in the first few days of life. The aim of the present study was to compare the effect of foremilk; hindmilk, which has been known to have more fat content than foremilk; and sterile water in reducing pain in newborns undergoing minor painful procedures.

METHODS

Sixty-two healthy term infants requiring a heel prick blood sample for screening tests were randomly allocated to receive 2 mL of foremilk, hindmilk or sterile water. Median crying time, duration of the first cry, percent change in heart rate, maximum heart rate and neonatal facial coding system scores were recorded to assess the infants' response to pain.

RESULTS

Statistically significant differences between the three groups were not found in terms of crying time, duration of the first cry, percent change in heart rate or maximum heart rate (P = 0.19, P = 0.08, P = 0.22 and P = 0.91, respectively). When the mean pain scores of the groups were compared at 0, 1, 2 and 3 min, there was no statistically significant difference between the three groups (P = 0.58, P = 0.55, P = 0.58 and P = 0.84 for 0, 1, 2 and 3 min, respectively).

CONCLUSION

Although hindmilk has a minor superiority in terms of crying time, duration of the first cry and percent change in heart rate, it does not reach statistical significance. It is concluded that neither foremilk nor hindmilk is superior in relieving pain when compared to placebo.

A quantitative study of fungiform papillae and taste pore density in adults and children

Male children (8-9 years) are reported to have a higher sensitivity than male adults to the sweet tastant sucrose when small regions of the anterior tongue are stimulated. The present study investigated the hypothesis that the higher sensitivity was due to a greater density of fungiform papillae and taste pores (buds), since it has been reported in adults that increased densities of these two structures correlates with increased taste suprathreshold sensitivity [Physiol. Behav. 47 (1990) 1213]. Quantitative measures of the number and size of papillae and pores in two areas of the tongue that had been shown to have a higher sensitivity for sucrose were achieved in 20 male children 8-9 years of age and 20 adults 18-30 years of age, using videomicroscopy and NIH Image software. Customized templates and a red food dye were used to define the equivalent tongue locations across the 40 subjects and taste pores were stained with methylene blue. Children were found to have substantially smaller papillae than adults but significantly higher papilla densities in both areas. Similar numbers of taste pores per papilla were found for both groups, resulting in children having much higher taste pore densities in each area than adults. Other differences included smaller taste pore diameters in children compared to adults, and the papillae tended to be rounder in children. Overall, the results support the hypothesis that the higher densities of fungiform papillae and taste pores in children underlie their greater sensitivity for sucrose in the two areas. In addition, the anatomical differences between adults and children indicate the sense of taste is in a state of development during mid-childhood.

Reduction of pain response in premature infants using intraoral sucrose

The potential of sucrose to reduce the pain response in a group of healthy premature infants was investigated. Fifteen infants of 32-34 weeks postmenstrual age were tested in a blind crossover manner on two separate occasions no more than two days apart. Either 1 ml of 25% sucrose solution or sterile water was syringed into the baby's mouth 2 minutes before routine heel lancing. Response to the painful stimuli was measured by duration of cry and by facial expression (pain score). There was a significant reduction in the duration of first cry, the percentage of time spent crying in the 5 minutes after heel prick, and the pain score in the sucrose treated group. It is concluded that sucrose has analgesic effects in healthy premature infants.

Effect of non-sucrose sweet tasting solution on neonatal heel prick responses

A substance commercially described as 'sugar free,' used as a sweetener for paracetamol suspension, was evaluated on measures of neonatal pain. Sixty infants were randomly allocated to receive one of four solutions before heel stab blood sampling: sterile water (placebo); 25 or 50% sucrose (weight/volume); and the commercial sweet-tasting solution. There was a significant reduction in crying time and pain score 3 minutes after the painful stimulus in all groups compared with the controls. It is concluded that this sweet-tasting solution has analgesic effects as potent as those of concentrated sucrose solutions.