from The Century Dictionary and Cyclopedia

  • n. The primitive chorion; the outer envelop of an ovum: in man and some other animals specially known as the zona pellucida.


Sorry, no etymologies found.


  • In Figure 1.138 the tufted it prochorion (dd apostrophe) encloses the germinal vesicle, the wall of which consists of the two primary layers.

    The Evolution of Man — Volume 1

  • At the same time, small structureless tufts or warts are deposited on the surface of the outer ovolemma or prochorion, which has been raised above the embryonic vesicle (Figures 1.112 to 1.114 a).

    The Evolution of Man — Volume 1

  • From this stage the envelope is called the external membrane, the primary chorion or prochorion (a).

    The Evolution of Man — Volume 1

  • But in most animals they at once begin to change; the change consists partly in the formation of connections with the yelk, which serve to nourish the ovum, and partly of external membranes for their protection (the ovolemma, or prochorion).

    The Evolution of Man — Volume 1

  • AC amniotic cavity, UV yelk-sac or umbilical vesicle, ALC allantois, al pericoelom or serocoelom (inter-amniotic cavity), sz serolemma (or serous membrane), pc prochorion (with villi).)

    The Evolution of Man — Volume 1


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