Specification of the Body Axes and The Body Plan Embryos can be thought of as being constructed with three orthogonal spatial axes (cephalocaudal, dorsoventral and laterolateral), plus a temporal axis. In mammalian embryos, axes cannot be specified at very early…
Genes in Development Study of secondary oocytes before and after fertilization, and of the selection of embryos for implantation after in vitro fertilization, has identified the range of maternal genes ready for expression to ensure cleavage, morula and blastocyst formation. Embryonic…
Conceptus with a Bilaminar Embryonic Disc At stage 6 the conceptus is composed of the walls of three cavities. The large chorionic cavity is surrounded by a meshwork of trophoblast and developing villi, and lined with extraembryonic mesoblast. The chorion,…
Implantation Implantation involves the initial attachment of the trophoblastic wall of the blastocyst to the endometrial luminal epithelium, stimulating the decidual response. The blastocyst is present within the uterine cavity for some 72 hours prior to implantation, and during this…
Understanding the spatial and temporal developmental processes that take place within an embryo as it develops from a single cell into a recognizable human is the challenge of embryology. The control of these processes resides within the genome; fundamental questions…
Introduction From a morphological point of view, most anatomy textbooks have described the skeletal muscles of the human body as being discrete actuators with clear origins and insertions ( ). Recent analyses of published anatomical cadaveric studies have challenged this…
Main nerve trunks contain many thousands of axons. When a trunk is stretched, but not ruptured, by dislocation of, say, the femoral or humeral heads, or by the nearby passage of a bullet, the axons within that nerve may respond…
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Introduction Biological electron microscopy (EM) is pivotal in life science research. A measure of its ubiquity is the diversity of its capacity, e.g. three-dimensional structural information about proteins and viruses at Å resolution; three-dimensional reconstructions of cellular organelles and tissues…