TGF-ß1 Inhibits Growth and Branching Morphogenesis In Embryonic Mouse Submandibular and Sublingual Glands in Vitro: (Salivary glands/extracellular matrix/epithelium/mesenchyme/organ culture).

Members of the TGF-ß superfamily of polypeptides are key regulators in developmental processes. Several studies have shown that expression of TGF-ß mRNA and protein are developmentally regulated and that both are prominently expressed in tissues undergoing epithelial-mesenchymal interactions such as branching morphogenesis. It has been shown that TGF-ß1 protein is present in E 14 mouse submandibular glands at a time when branching is already establihsed. Here we demonstrate by RT-PCR and immunofluorescence that both TGF-ß1 mRNA and protein are present in E 13 submandibular and sublingual glands at a time when branching is being initiated. Addition of TGF-ß1 to E 13 rudiments resulted in reductions in organ size and inhibition of branching. Sensitivity to TGF-ß1 depended on the developmental stage of the rudiments (early or late E 13) and the dose of growth factor used. TGF-ß1 Also caused epithelial abnormalities, notably treated organs had elongated ducts. The effects were most pronounced in the sublingual gland. Taken together these results suggest a regulatory role for endogenous TGF-ß1 in the growth and morphogenesis of mouse salivary glands.

Growth and Morphogenesis of Embryonic Mouse Organs on Non-Coated and Extracellular Matrix-Coated Biopore Membrane: (organ-culture/growth/morphogenesis/extracellular matrix/Biopore).

Embryonic mouse salivary glands, pancreata, and kidneys were isolated from embryos of appropriate gestational age by microdissection, and were cultured on Biopore membrane either non-coated or coated with type I collagen or Matrigel. As expected, use of Biopore membrane allowed high quality photomicroscopy of the living organs. In all organs extensive mesenchymal spreading was observed in the presence of type I collagen or Matrigel. However, differences were noted in the effects of extracellular matrix (ECM) coatings on epithelial growth and morphogenesis: salivary glands were minimally affected, pancreas morphogenesis was adversely affected, and kidney growth and branching apparently was enhanced. It is suggested that these differences in behaviour reflect differences in the strength of interactions between the mesenchymal cells and their surrounding endogenous matrix, compared to the exogenous ECM macromolecules. This method will be useful for culture of these and other embryonic organs. In particular, culture of kidney rudiments on ECM-coated Biopore offers a great improvement over previously used methods which do not allow morphogenesis to be followed in vitro.