Rat EGF (Epidermal Growth Factor) is a growth factor peptide belonging to the EGF family of ligands, which also includes transforming growth factor-α (TGF-α), amphiregulin (AREG), heparin-binding EGF-like growth factor (HB-EGF), betacellulin (BTC), and epiregulin (EREG) that signal through the epidermal growth factor receptor (EGFR/ErbB1) to regulate cell proliferation, differentiation, and tissue repair. In rats (Rattus norvegicus), EGF is produced by epithelial cells, fibroblasts, macrophages, and glandular tissues, with particularly high expression in the submandibular (salivary) glands, which serve as a major source of circulating EGF. Binding of EGF to EGFR activates intracellular signaling pathways such as MAPK/ERK, PI3K–AKT, and JAK/STAT, promoting cell proliferation, survival, and tissue regeneration during development and after injury. In rat physiology, EGF plays key roles in skin repair, gastrointestinal epithelial maintenance, and organ development. Rats are widely used as animal models for studying epithelial biology, wound healing, and gastrointestinal disease, and EGF signaling has been investigated in rat models of gastric ulcer healing, where EGF promotes regeneration of gastric mucosal epithelium and restoration of mucosal integrity, providing insights into growth factor–mediated tissue repair relevant to human medicine.