from The Century Dictionary and Cyclopedia
- n. In embryology, a layer of cells; specifically, the same as germ-layer, or one of the embryonic layers of cells — ectoderm, mesoderm, entoderm — from which the organs of the animal body are developed.
Sorry, no etymologies found.
B longitudinal section through the axis, g primitive-gut cavity, a primitive mouth-aperture, i inner cell-layer (entoderm, endoblast, gut-layer), e external cell-layer (outer germinal layer, ectoderm, ectoblast, or skin-layer).
The outer covering is the simple cell-layer of the epidermis (E).
Its functions are represented by the simple cell-layer of the ectoderm, which the lower Metazoa have inherited from the Gastraea
As regards the remaining organs of the Amphioxus, we need only mention that the gonads or sexual glands are developed very late, immediately out of the inner cell-layer of the body-cavity.
In these cases the simple cell-layer of the ectoderm is at once skin, locomotive apparatus, and nervous system.
The episomites or dorsal coelom-pouches of the Acrania, Cyclostomes, and Selachii (Figure 1.161 h) first develop from their inner or median wall (from the cell-layer that lies directly on the skeletal plate