For example, after comparing the external embryonic morphologies of 39 species of vertebrates, including representatives from agnathans, cartilaginous fishes, bony fishes, amphibians, reptiles, birds, and mammals, Richardson et al. (1997) concluded that there is no vertebrate phylotypic stage.
Based on microscopic observation of the external embryonic features at 25 °C, the developmental stage was assigned according to Campos-Ortega and Hartenstein's table [ 26, 27].
Matricellular proteins are a set of non-structural extracellular matrix (ECM) proteins, mainly including thrombospondins (TSPs), OPN, tenascins, SPARC, POSTN and CCNs, which do not exert a primary role in tissue architecture but regulate similar biological functions in response to external stimuli during embryonic development, tissue injury, inflammation and tumor progression (Bornstein, 1995).
To describe the external development of embryonic series I suggest the following protocol: Ordering: Primarily, specimens should be ordered by a comparative synopsis of the embryos' age and the development of reference organs, such as the number of somites, or as often used, the limb bud development [78] [79].
Embryos were scored as gastrulation defective if Z2/ Z3 were found to remain among the external layer of embryonic nuclei (Powell-Coffman et al. 1996).
There are many experimental advantages of the zebrafish, including the ability to generate large numbers of optically translucent embryos by external fertilization, rapid embryonic maturation, a high degree of cellular and developmental homology to mammals, permeability to small molecules, a nearly complete genome sequence, and a variety of mutants and functional genomic and genetic tools.
In vitro fertilization separates the internal and external portions of the embryonic program.
Our work highlighting the early abca12 expression in the EVL seems to support the conclusions that EVL forms the external layer of the embryonic and larval dermis and represents the initial differentiation of a true epidermis (Fukazawa et al., 2010).
Again, proper development of the genital tubercle and the embryonic anlage of external genitalia in the male phenotype also require coordinated outgrowth of the mesodermally-derived mesenchyme and extension of the endodermal urethra within an ectodermal epithelial capsule.
A key part of the job will be to oversee the external action service, the EU's embryonic diplomatic service, which has almost 200 offices all over the world.
Herein we test the hypothesis that the basement membrane protein laminin α5 (LAMA5) plays a key role in the development of the mouse genital tubercle, the embryonic anlage of the external genitalia.
