Article

Development and Maturation of the Pediatric Human Vocal Fold Lamina Propria

Harvard University, Cambridge, Massachusetts, United States
The Laryngoscope (Impact Factor: 2.14). 02/2005; 115(1):4-15. DOI: 10.1097/01.mlg.0000150685.54893.e9
Source: PubMed

ABSTRACT

To identify characteristic patterns of maturation of the human vocal fold lamina propria as it develops into a mature structure.
Histologic evaluation of sectioned true vocal folds from 34 archived larynges ages 0 to 18 years using hematoxylin-eosin, trichrome, Alcian blue pH 2.5, Weigert reticular, and Miller's elastin stain.
Pathology department at a tertiary care children's hospital.
At birth and shortly thereafter, there exists a relative hypercellular monolayer of cells throughout the lamina propria. By 2 months of age, there are the first signs of differentiation into a bilaminar structure of distinct cellular population densities. Between 11 months and 5 years, two distinct patterns are seen: 1) this bilaminar structure and 2) a lamina propria where there exists a third more hypocellular region immediately adjacent to the vocalis muscle (this region is similar to the superficial hypocellular region found just deep to the surface epithelium). By 7 years of age, all of the specimens exhibit this transition between the middle and the deeper layers according to differential density of cell populations. A lamina propria structure defined by differential fiber composition (elastin and collagen fibers) is not present until 13 years of age and then is present throughout adolescence.
Using the classic adult model of fiber composition and density to differentiate the layered structure of the lamina propria of the human vocal fold may not adequately allow for a thorough description of the process of maturation and development. Rather, distinct regions of cell density are seen as early as 2 months postpartum, and the model of cellular distribution may serve better to describe the lamina propria as it develops. Cell-signaling processes that shape the formation of the lamina propria appear to produce layered populations of differential cell density that in turn will later produce differential fiber compositions. Early development therefore can be followed by evaluating the maturation of these differing cell populations. Future studies are needed to quantify these cell distribution patterns, to study the cell signaling processes that trigger this maturation, and to correlate these findings with mechanical modeling.

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    • "Applying hierarchical multiple regression, a significant predictor of the individual fo range in crying was the ratio mean E2/SHBG (Table 2). There was a negative association between mean E2/SHBG and the fo range (standardized linear regression coefficient: −0.55, t[19]= −2.796, P = 0.012; Figure 2). Girls deviate from the regression line more than boys; theHighest concentrations were found at the fourth and eighth week with values declining to prepubertal levels at 20 weeks. "
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    ABSTRACT: Objective: To evaluate whether the puberty-like sex hormone surge during the first months of life (mini-puberty) affects fundamental frequency (fo) in infant crying as one would derive from hormone influences on voice in adults. Study design: Populational prospective study. Participants: Twenty healthy normal-hearing infants (nine boys) were recruited for participation. Methods: Spontaneously uttered cries were collected from each infant at 8 weeks of age. The cries were acoustically analyzed for mean fo and fo range. The fo properties were correlated to the average serum levels of bioavailable estradiol (E2) (mean E2/sex hormone-binding globulin [SHBG]) and testosterone (T) (mean T/SHBG) across the second month of life. Results: Whereas no significant hormone effect was found for mean fo, a significant negative correlation (r = -0.55) was found between fo range and mean E2/SHBG. No indication for a T influence on fo features was found at this age. Although girls showed a slightly higher mean E2 concentration than boys did, the observed differences in cry fo range were judged to be reflective of an infant's serum concentration of E2 rather than a sex-based difference. Conclusion: In the absence of laryngeal size differences between female and male infants, the result was interpreted as indicative of an E2 influence on viscoelastic properties of the vocal folds. In our opinion, the investigation of young infants' vocalizations during the early postnatal surge of sex steroids (mini-puberty) may advance our understanding of the mechanisms mediating average sex differences in vocal development and early communication.
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    • "In other words, production is importantly " supralaryngeal, " with the tongue, mandible, and lips used to flexibly and dynamically create the many sounds of each different language. Human vocal-fold structure and response also show important developmental changes (Schweinfurth and Thibeault, 2008; Hartnick et al., 2005). One evident consequence is that the vibration regimes underlying the psycheshattering shrieks and screams characteristic of young children become difficult, if not impossible, for adults to produce. "

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    • "Other investigators have described the presence of fibrous structures , such as collagen and elastic fibres, in the lamina propria of the vocal folds of fetuses after 21 weeks of age (Fayoux et al. 2004). Despite the controversy regarding the distribution of extracellular matrix components in the vocal fold lamina propria, it has been established that after birth the vocal fold continues its process of development and maturation, mediated by exogenous stimuli, mainly phonation, until it attains the highly complex structure seen in adults (Hartnick et al. 2005). On the basis of these observations, and in the light of current knowledge regarding the ultrastructural and histochemical properties of elastic and collagenous system fibres, we conceived this study to investigate the structural organization of the lamina propria of the fetal vocal fold during the late prenatal period. "
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