Type and distribution of cells in goat temporomandibular joint discs and its significance in tissue engineering design

Weina SHU; Hong KANG; Weiping ZHANG; Xin LI; Guangjie BAO

ABSTRACT

BACKGROUND:

There is no common cognition in the cell type in the temporomandibular joint(TMJ)discs,and names describing TMJ disc cells also vary a lot.

OBJECTIVE:

To characterize the type and the distribution of cells in the TMJ disc of goats DESIGN,TIME AND

SETTING:

A single sample observation was completed in Cettutar and Motecutar Biologicat Center and Electron Microscope Center of Lanzhou University from March to May in 2007.MATERlALSTMJ discs were obtained from two one-month-old healthy goats that were slaughtered freshly.

METHODS:

Bilateral TMJ discs of goats were cut off completely and were divided into 6 parts by 3 cuts in the major axis direction (mediolaterally)and 2 cuts in the minor axis direction(anteroposteriorly).Then the marked samples were fixed in 10%neutral formalin Iiquid for 24 hours and embedded by paraffin.MAIN OUTCOME

MEASURES:

Hematoxylin and eosin staining were used to identify regional variation of cell type and cellnumbers.Toluidine blue staining and collagen type Ⅰimmunohistochemical assay were performed to test the distribution of collagens.Transmission etectren microscopy was used to observe the ultrastructure of cells of goat TMJ discs.

RESULTS:

TMJ discs were comprised of cells and collagen fibers distributing unevenly.Collagens were mostly type Ⅰ.Collagen fibers were wave or crimping and approximately parallel to each other.with cells scattered in their matrix.Fibroblast-like cells and chondrocyte-like cells were the main two types of cells existing,with the former predominating over the later in a ratio of 2.051 approximately.There were no significant regional differences in cell type and distribution statistically.Transmission electron microscopy denoted that fibroblast-iike cells have fairly larger fusiform or irregular nuclei with very few organelles,while the chondrocyte-like cells exhibited round or elliptical nuclei,well defined pericellular electron lucent zones,unconspicuous cytocysta and non-distinctive pseudopodia

CONCLUSION:

There are no significant differences in type,number and arrangement of cells in TMJ discs of one-month-old goats statistically,with Fibroblast-like cells predominating slightly over chondrocyte-like cells.