Section through the anterior part of the area pellucidain front of the primitive streak.
Junction between the white-yolk spheres and the hypoblast cells at the passage from the area pellucida to the area opaca.
Section through anterior part of area pellucida in front of embryonic shield.
Surface-view of area pellucida of an eighteen-hour chick-embryo.
The layer of cells lining the interior of the vesicle next to the zona pellucida forms Rauber's "Deckschichte" or prochorion.
The zona pellucida appears thickened, and contains many spermatozoa which failed to penetrate the ovum.
The ovum is, the reader will remember, first surrounded by the transparent structureless ovolemma or zonapellucida (Figures 1.
In the course of further growth the area pellucida soon becomes pyriform, the narrower extremity being the posterior.
At the edge of the area pellucida the hypoblast becomes continuous with a thickened rim of material, underlying the epiblast, and derived from the original thickened edge of the blastoderm and the subjacent yolk.
The area pellucida gradually assumes an oval form, and at the same time becomes divided into a posterior opaque region and an anterior transparent region.
During these changes in external appearance there grow from the sides of the primitive streak two lateral wings of mesoblast cells, which gradually extend till they reach the sides of the area pellucida (fig.
This ring is regarded by these authors as representing the peripheral part of the area pellucida of Birds, which does not become converted into the body of the embryo.
In the region of the area pellucida there is placed below the epiblast a more or less irregular layer of cells.
The areapellucida is at this stage nearly spherical.
Near the front border of the areapellucida (1) it has the general characters of the hypoblast of the duck's blastoderm just described.
Foulis regards the zona pellucidaas a product of the ovum and not of the follicle.
The primitive streak is however the most interesting structure in the area pellucida at this stage.
We may now pass to the consideration of the part of the area pellucida in front of the primitive streak.
The simplest method of testing the point is by measuring the distance between the front end of the primitive streak and the front border of the area pellucida at different stages of growth of the primitive streak.
These cells, especially in front, are characterized by their numerous yolk spherules, and give the impression that part of the area pellucida has been, so to speak, reclaimed from the area opaca.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "pellucida" in a variety of sentences. We hope that you will now be able to make sentences using this word.
