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Immunohistochemical localization of parathyroid hormone-related protein in developing mouse Meckel's cartilage and
12nd Department of Orthodontics, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.
Abstract:
In order to clarify the role of parathyroid hormone-related protein (PTHrP) during Meckel's cartilage and mandibular development, an immunohistochemical study of PTHrP and its receptor, PTH/PTHrP receptor, was designed to examine their localization in the anterior region of Meckel's cartilage including the rostrum, which is known to contribute to the development of the mandible. Meckel's cartilage was first observed on day 13 of gestation and PTHrP was faintly localized in the chondrocytes. On day 16 of gestation, at the stage of elongation and initiation of endochondral ossification in Meckel's cartilage, PTHrP was localized in the chondrocytes located in the area showing interstitial growth and in and around the nuclei of hypertrophic chondrocytes undergoing endochondral ossification. At day 18 of gestation, endochondral ossification was spread over the entire area proximal to the molar region in Meckel's cartilage, except in the mesial fusion site formed by immature chondrocytes. PTHrP was localized in the osteoblasts adjacent to the calcified matrix, but had disappeared from the chondrocytes forming Meckel's cartilage. The localization of PTH/PTHrP receptor was similar to that of PTHrP. These results show that localization of PTHrP is spatially and temporally related to the growth of Meckel's cartilage.
Insights
Parathyroid hormone-related protein (PTHrP) plays a key role in Meckel
Area of Science:
- Developmental Biology
- Endocrinology
- Skeletal Biology
Background:
- Meckel's cartilage is crucial for mandibular development.
- Parathyroid hormone-related protein (PTHrP) is implicated in skeletal development.
- The specific role of PTHrP in Meckel's cartilage development requires clarification.
Purpose of the Study:
- To investigate the localization and role of PTHrP and its receptor during Meckel's cartilage and mandibular development.
- To examine the spatiotemporal expression patterns of PTHrP and PTH/PTHrP receptor in the developing mandible.
Main Methods:
- Immunohistochemical analysis of PTHrP and PTH/PTHrP receptor.
- Examination of embryonic tissues from gestation days 13, 16, and 18.
- Focus on the anterior Meckel's cartilage, including the rostrum.
Main Results:
- PTHrP was detected in Meckel's cartilage chondrocytes early in development (gestation day 13).
- During elongation and ossification (day 16), PTHrP localized to interstitial growth zones and hypertrophic chondrocytes.
- By day 18, PTHrP shifted to osteoblasts, while the receptor showed similar localization patterns.
- PTHrP expression correlated with Meckel's cartilage growth phases.
Conclusions:
- PTHrP localization is spatially and temporally linked to Meckel's cartilage development.
- PTHrP and its receptor are involved in regulating chondrocyte and osteoblast activity during mandibular formation.
- These findings elucidate the role of PTHrP signaling in craniofacial skeletal development.