Introductory Remarks.<br>Methodology.<br>General Observations on the Staging of Postimplantation Mouse Embryos.<br>General Observations on the Plates.<br>Embryogenesis.<br>Assessment of Developmental Stage of Pre- and Postimplantation Mouse Embryos Based on the Staging System of Theiler (1989):<br>Preimplantation Period.<br>Stages 1-5.<br>Postimplantation Period.<br>Stages 6-26.<br>Scanning Electron Micrographs, and Special Systems: External Appearance of Intact Embryos Isolated between 7.5-9.5 Days p.c. (Text Associated with Plate 42).<br>External Appearance of Intact Embryos Isolated between 9.5-11.5 Days p.c., and<br>Differentiation of the Limbs over the Period from 9.5-117.5 Days p.c. (Text Associated with Plates 43-145).<br>External Appearance of Intact Embryos Isolated between 11.5-118.5 Days p.c. (Text Associated with Plate 46).<br>Differentiation of the Cephalic Region in Embryos Isolated between 9.5-111.5 Days p.c.--Scanning Electron Microscopy Series (Text Associated with Plate 47).<br>Differentiation of the Eye--Scanning Electron Microscopy and Histological Series (Text Associated with Plates 48-153).<br>Differentiation of the Pituitary (Text Associated with Plates 54-157).<br>Development of the Tongue (Text Associated with Plate 58).<br>Closure of the Palate (Text Associated with Plates 59-162).<br>Morphology of the Spinal Cord (Text Associated with Plate 63).<br>Early Stages in the Development of the Heart (Text Associated with Plates 64 and 65).<br>Differentiation of the Lungs (Text Associated with Plate 66).<br>Histochemical Demonstration of Primordial Germ Cells (Text Associated with Plate 67).<br>Differentiation of the Urogenital Ridges, Gonads, and Genital Duct System (Text Associated with Plates 68-171).<br>Differentiation of the Kidney (Text Associated with Plate 72).<br>Discontinuities Occasionally Found in the Visceral Yolk Sac (Text Associated with Plates 73 and Plate 74, a-1f).<br>Differentiation of the Placenta (Text Associated with Plate 74, g-1i and Plate 75).<br>Disposition of the Extra-embryonic Membranes Associated with Various Types of Twinning (Text Associated with Plates 76-179).<br>Asynchronous Implantation (Text Associated with Plate 80).<br>Embryo Code Numbers for Serially-Sectioned Embryos Illustrated in Plates 1-141.<br>Chapter References.