(In pollen) innermost layer of cells of the pollen sac wall that nourish the developing pollen grains;
Membrane in spore-generating area of ferns.
A layer of specialized reflecting cells in the choroid behind the retina of the eye.
A layer of fibers from the corpus callosum forming the roof and lateral walls of the inferior and posterior horns of the lateral ventricles of the brain. This layer separates the optic radiation from the ventricle and passes to the temporal and occipital lobes.