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In vitro analysis of the spatial organization of chondrogenic regions of avian mandibular mesenchyme
Author(s) -
Langille Robert M.
Publication year - 1994
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/aja.1002010106
Subject(s) - chondrogenesis , anatomy , mesenchyme , quail , biology , cartilage , limb bud , zone of polarizing activity , mandible (arthropod mouthpart) , limb development , microbiology and biotechnology , embryo , embryogenesis , ectoderm , endocrinology , botany , genus
The mechanism(s) which control patterning in the face remain elusive, due in large part to the absence of morphologically identifiable controlling regions such as the AER of the limb bud. In order to identify the controlling region(s) and timing of patterning in the face, an investigation was launched to determine the spatial organization of tissues within this region, beginning with the chondrogenic zones of the avian (chick and quail) mandible. The mandibles from HH stage 23/24 chick and equivalent stage quail embryos were initially bisected in three planes giving rostral or caudal, proximal or distal, and medial or lateral halves. The mesenchyme from these various regions was isolated, plated out in high density micromass cultures, and grown for 4 days. Additionally, further cultures were grown, consisting of mandibular mesenchyme subdivided into quarters along the long axis of the mandible (e.g., rostro‐proximal quarter) as well as the bisecting of medial or lateral halves (e.g., medialrostral quarter). Nodule number and area were determined by morphometric analysis for each culture as well as whole mandible controls. The demarcation between chondrogenic and non‐chondrogenic regions was dramatic. Of the bisected halves, proximal and lateral were the most chondrogenic with the lateral subdivision displaying much more cartilage than whole mandible. The nodules of the lateral cultures fused into a sheet of cartilage. In constrast mesenchyme from the medial half was virtually non‐chondrogenic. When ranked by the amount of chondrogenesis, the order was, lateral > proximal = whole = core > distal > caudal > rostral > periphery ≫ medial. Interestingly, when subdivided further an altered pattern appeared. For example, the rostromedial quarter displayed a sheet of cartilage; more than the disto‐lateral or even the proximolateral which, based on the bisected‐mandible data, should have yielded the most cartilage. One possible explanation for the variance in the cartilage produced by the quartered mandibles from the amount predicted by the bisected‐mandible data is that further isolating portions of the mesenchyme changed the ratios of other cell types in the cultures and that cell‐cell interactions affect chondrogenic differentiation as suggested for limb mesenchyme. © 1994 Wiley‐Liss, Inc.