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This dissertation, "The Physiological Role of Transforming Growth Factor-beta in Gastrointestinal Development in the Pig" by Jie, Mei,, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled THE PHYSIOLOGICAL ROLE OF TRANSFORMING GROWTH FACTOR-BETA IN GASTROINTESTINAL DEVELOPMENT IN THE PIG Submitted by Jie Mei for the degree of Doctor of Philosophy at The University of Hong Kong in April 2004 Transforming growth factor-beta (TGF-β) has been detected in the milk of various species, including the pig. The concentration of TGF-β in the colostrum is particularly high. It has been speculated that milk-borne TGF-β may play a role in the postnatal adaptation of the gastrointestinal tract in suckling animals. However, a prerequisite for any physiological effects of milk-borne TGF-β in suckling animals is the presence of TGF-β receptors in the mucosa of the intestine. The objectives of the present study were to investigate (i) the developmental changes of TGF-β receptors in the intestinal mucosa in foetal and neonatal pigs, (ii) the effects of intestinal exposure to milk-borne TGF-β on intestinal TGF-β receptor expression, and (iii) the changes of endogenous expression of TGF-β in the intestinal mucosa of neonatal pigs in association with weaning. Western blot analysis and immunohistochemical staining showed the presence of the three types of TGF-β receptors (RI, RII and RIII) along the small intestine in foetal and postnatal pigs. In foetal pigs of 90 and 105 days of gestation, the receptors were predominantly localized at the intestinal crypts. At birth, the staining