Tongue development in stillborns autopsied at different gestational ages

Macrophage is crucial for tongue development by regulating myogenesis and vascularization

BACKGROUND

Abnormal tongue development is a craniofacial deformity that affects dental-maxillofacial esthetics and function. Recent evidence has identified macrophages as multi-functional immune cells crucial for heart and brain development. However, it is still unknown whether macrophages affect tongue development. Therefore, this study aims to assess the distribution, phenotype, and roles of macrophages in the developing tongue.

METHODS

In this study, immunohistochemical (IHC) and multiplex immunofluorescence (mIF) staining were conducted on C57BL/6 mice at embryonic day (E) 13.5, E14.5, E16.5, and E18.5 to analyze the distribution and phenotype of macrophages. Hematoxylin-Eosin (HE), IHC, IF, and mIF staining were also performed on embryonic CX3 CR1-CreERT2; Rosa-DTA conditional macrophage-depleted mice to investigate the effects on fetal tongue development and elucidate mechanisms from myogenesis, vascularization, and cell apoptosis. Statistical significance between the two groups was determined using unpaired two-tailed Student's t-tests. For comparisons involving three or more groups, one-way analysis of variance (ANOVA) followed by Tukey's multiple comparison tests was utilized. A significance level of P < 0.05 was set for statistical significance.

RESULTS

Macrophages were present in the developing tongue from E13.5 to E18.5, with a majority being of the M2 phenotype. Depletion of macrophages resulted in abnormal tongue morphology, decreased tongue height, width, and size, as well as reduced and disorganized muscle fibers. Depletion of macrophages also increased apoptosis. Vascular morphogenesis was impacted, with reductions in the luminal and vascular wall cross-sectional areas of the lingual artery. Vascular endothelial cells were reduced and disorganized with decreased expression of VEGFA and TGF-β1. Moreover, macrophages were located near vascular endothelial cells and secreted pro-angiogenic factors, suggesting their involvement in promoting vascularization.

CONCLUSIONS

Our findings indicate that macrophages play crucial roles in fetal tongue development by affecting myogenesis, cell apoptosis, and vascular growth.

Fetal Micro and Macroglossia: Defining Normal Fetal Tongue Size

OBJECTIVES

Abnormal fetal tongue size is a phenotypic feature of various syndromes including Beckwith-Wiedemann, Pierre-Robin, oromandibular limb hypoplasia, chromosomal aberrations, etc. Current data regarding normal fetal tongue size are limited. Hence, micro/macroglossia are subjectively determined. The aim of the study was to construct a contemporary fetal tongue nomogram and to assess its clinical contribution.

METHODS

A prospective cross-sectional study was performed in well dated, low risk, singleton pregnancies. Fetal tongues were measured by 5 trained sonographers. Highest quality images were selected. Intra- and interobserver variability was assessed. Tongue length, width, area, and circumference 1st to 99th centiles were calculated for each gestational week. Based on the normal tongue size charts, we created a Tongue Centile Calculator.

RESULTS

Over 18 months, 664 tongue measurements were performed. A cubic polynomial regression model best described the correlation between tongue size and gestational age. The correlation coefficient (r² ) was 0.934, 0.932, 0.925, and 0.953 for tongue length, width, area, and circumference, respectively (P < .001). Intra- and interobserver variability had high interclass correlation coefficients (>0.9). Using the new charts, we were able to identify 2 cases of macroglossia, subsequently diagnosed with Beckwith-Wiedemann, and 4 cases of microglossia, 3 associated with Pierre-Robin sequence, and 1 associated with persistent buccopharyngeal membrane.

CONCLUSIONS

We present novel fetal tongue size charts from 13 to 40 weeks of gestation. Clinical application of these nomograms may be beneficial in the prenatal diagnosis of syndromes or malformations associated with abnormal fetal tongue size.

Morphometric development of the tongue in fetal cadavers

PURPOSE

The tongue is a specific organ for the sense of taste. It consists of the striated muscle and mucous membrane. Furthermore, it helps the functions of speech, chewing, and swallowing. In this study, we aimed to reveal some morphometric properties of the tongue in fetal cadavers.

METHODS

The study was conducted on a total of 45 fetal tongues (25 male tongues, 20 female tongues) aged between 17 and 40 weeks. The fetuses were divided into three groups as trimester II, trimester III, and full term. For each tongue, the length, width, area, free tongue length, and the terminal sulcus angle were measured using Image J program. The free tongue length/tongue length ratio was examined.

RESULTS

The obtained data were compared according to the trimester groups and genders. It was determined that the tongue length, width, area, and free tongue length increased during the trimesters and that there was no significant difference in the terminal sulcus angle and the free tongue length/tongue length ratio between the trimesters. No significant difference was found in all parameters between the genders.

CONCLUSIONS

This study presented significant data on morphometric development of the tongue. These data are thought to be useful for determining the anomaly and variations of the tongue.