Ultrastructural analysis of fibroblasts of the laryngeal lamina propria in presbyphonia

• Grant number: 25/12207-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2025
• End date: September 30, 2026
• Field of knowledge: Health Sciences - Medicine - Pathological Anatomy and Clinical Pathology
• Principal Investigator: Regina Helena Garcia Martins
• Grantee: Amanda Machado
• Host Institution: Faculdade de Medicina (FMB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Introduction: As occurs throughout the body, the structures of the larynx also undergo the process of senescence, especially the vocal folds. After the age of 65, approximately 20% of people complain of vocal changes due to several factors, especially changes in the mucous membrane of the vocal folds and atrophy of the vocal muscle. Previous studies have demonstrated an increase in collagen fibers in the lamina propria of the vocal folds of elderly individuals, as well as a decrease in elastic fibers and hyaluronic acid, important components in the flexibility of the vocal folds during phonation. The exact pathophysiological mechanisms that justify these findings are not fully elucidated. The hypotheses are limited to the increase or lack of control of fibroblast activity or the slower rate of degradation and renewal of the fibrous matrix. Fibroblasts play a crucial role in the maintenance, development and repair of the extracellular matrix, in addition to the synthesis of the fibrous matrix, aiding in tissue repair. Objective: to analyze the ultrastructure of fibroblasts in the lamina propria of the larynxes of elderly individuals, comparing them to the larynxes of young adults in order to identify relevant structural changes that may add information to the pathophysiology of presbyphonia and thus better direct treatments. Case series and methods: 17 vocal folds of individuals autopsied at the Autopsy Service of the Pathology Department of the Botucatu School of Medicine will be included in this study and distributed into two groups according to age range: Control group (n-8 - age between 18 and 40 years) and elderly group (n-8 - age above or equal to 75 years). The vocal folds will be dissected, fixed in 2.5% glutaraldehyde and prepared for transmission electron microscopy study. After preparation, the slides will be analyzed frame by frame to identify the fibroblasts, which will be photographed at increasing magnifications and analyzed for: shape, nucleus/cytoplasm ratio, chromatin configuration, organelles (endoplasmic reticulum, mitochondria, Golgi complex) and presence of vesicles. The Image J program will be used to calculate the nucleus/cytoplasm ratio. The number of fibroblasts estimated in the analyses of each group will be close to 100 to 150. Only fibroblasts with a characteristic spindle-shaped appearance will be selected for statistical analysis of the results. (AU)