Epigenetic Remodeling of Pharyngeal Arch Derivatives: Analyzing the Impact of Maternal Microplastic Exposure on Craniofacial Morphogenesis
- May 7
- 2 min read
Updated: May 17
https://doi.org/10.66715/ijcar/2026v2.i1.7686 | 2026 | Volume 2 | Issue 1 | Page 76-86
Dr. Jayaprakash B R, Professor and HOD, Department of Anatomy, Alva's Institute of Medical Sciences and Research Center, Moodubidire, Dakshina Kannada District, Karnataka State, Pin- 574227
Abstract
Background: Craniofacial anomalies constitute a significant proportion of congenital birth defects worldwide. While genetic mutations are well-documented etiological factors, emerging evidence points toward environmental toxicants as potent disruptors of embryonic development. Among these, microplastics (MPs) have surfaced as ubiquitous environmental pollutants capable of crossing the placental barrier. This study investigates the impact of maternal microplastic exposure on craniofacial morphogenesis, specifically evaluating the epigenetic remodeling (DNA methylation and histone modifications) within neural crest cells migrating into the pharyngeal arches.
Methodology: An experimental rodent model study was conducted at Alva's Institute of Medical Sciences. Pregnant Wistar rats (n = 40) were randomly assigned to four cohorts: a control group and three experimental groups exposed to varying concentrations of polystyrene microplastics (0.1 mg/L, 1.0 mg/L, and 10 mg/L} via drinking water throughout gestation days (GD) 1–18.
Morphological Analysis: Embryos harvested at GD 18 underwent stereomicroscopic examination to assess skeletal and cartilaginous anomalies of the first and second pharyngeal arch derivatives (Meckel's cartilage, hyoid apparatus, mandibular and maxillary components).
Molecular & Epigenetic Analysis: Tissue segments from the pharyngeal arches were isolated to analyze global DNA methylation profiles, histone H3 acetylation levels, and the expression patterns of core morphogenetic genes (Hoxa2, Pax9, and DlX5/6) using RT-qPCR and Western blotting.
Results
Maternal exposure to high concentrations of microplastics (10{ mg/L}) resulted in a 34/% incidence of visible craniofacial dysmorphism, including mandibular hypoplasia, cleft palate, and malformations of the auditory ossicles derived from the second arch. Molecular assays revealed:
Epigenetic Dysregulation: A significant, dose-dependent increase in global DNA hypermethylation within the pharyngeal arch tissue, alongside a corresponding down-regulation of histone H3K9 acetylation.
Gene Silencing: The key homeobox genes regulating jaw and skeletal identity—specifically Hoxa2 and DlX5—exhibited marked transcriptional silencing due to promoter hypermethylation (p < 0.01).
Cellular Apoptosis: Histological tracking confirmed accelerated apoptosis and restricted migration of cranial neural crest cells into the distal margins of the first pharyngeal arch.
Conclusion
Maternal microplastic ingestion induces severe craniofacial phenotypic variations by altering the epigenetic landscape of pharyngeal arch derivatives. This study demonstrates that MPs do not merely act as mechanical barriers or basic cytotoxins; rather, they disrupt the critical, time-sensitive epigenetic programming required for neural crest cell differentiation. These findings highlight an urgent public health concern regarding plastic pollution and provide a novel epigenetic framework for understanding environmentally induced craniofacial birth defects.
Keywords: Pharyngeal Arches, Craniofacial Morphogenesis, Microplastics, Epigenetics, DNA Methylation, Neural Crest Cells, Anatomy, Karnataka.