Antra are lacking in a few insectivores (Hemicentetes, Euriculus) because the granulosa cells swell and multiply to form corpora lutea, masses of yellow tissue.
The result in mammals is the formation of solid masses called corpora lutea, recognizable as prominent reddish-yellow bulges on the ovary.
Corpora lutea produce the hormone progesterone, which is essential for the maintenance of pregnancy.
The conversion of postovulatory follicles into structures more or less resembling mammalian corpora lutea has been demonstrated in numerous viviparous reptiles, amphibians, and elasmobranchs; in certain other fishes, including cyclostomes; and in some oviparous amphibians and reptiles.
All lemurs are characterized by a reflective layer (tapetum) behind the retina in the eye, but no fovea or macula lutea; a hairless, moist tip to the muzzle; a noninvasive (epitheliochorial) placenta; comblike forward-directed lower front teeth (with the exception of the aye-aye); and a claw ("toilet claw") on the second toe of the foot.
Two species of lotus, the sacred lotus (Nelumbo nucifera) and the American lotus (Nelumbo lutea), are the sole members of the aquatic family Nelumbonaceae.
Yellow birch, also called Silver Birch, orSwamp Birch, (Betula alleghaniensis, or B. lutea), ornamental and timber tree of the family Betulaceae, native to the northeastern part of North America.
A race of hybrids, developed by crossing the tree peony with the yellow Chinese P. lutea, has both single and double flowers, sometimes tinged with red.
The garden pansy (V. wittrockiana) is a hybrid, one of whose parents is V. tricolor, which is a weed of European grainfields, the other parents being V. lutea and V. altaica.
The other species is the American lotus, or water chinquapin (N. lutea, or N. pentapetala), found in the eastern United States and southward to Colombia.
The small central area of retina that subserves the most acute vision, called the macula lutea, has only one source of blood supply, the underlying choroid.
