No regular follicle is formed, but the odcyte absorbs nutriment from the remaining odgonia.
In many embryo Lamellibranchs a centro-dorsal primitive shell-gland or follicle has been detected.
At one point this is continuous with a layer of cells called the stratum granulosum which lines the outer wall of the follicle, but elsewhere the two layers are separated by fluid, the liquor folliculi.
When the follicle bursts, as it does in time, the ovum escapes on to the surface of the ovary.
In the centre of this antipedal area there has appeared (often at a very early period) a gland-like depression or follicle of the integument.