Maximum DNA synthesis during the midproliferative phase of the cycle (i.e. cycle days 8â10) correlates with the maximum number of mitoses in both the stromal and epithelial endometrial cellular elements, as well as with the midproliferative peak of plasma estradiol and nuclear estradiol receptors.
Some defining characteristics of angiosperms include flowers, carpels, and the presence of endosperm, a nutritive substance found in seeds, produced via a second fertilization event. However, some current studies suggest that endosperm is not unique to angiosperms.
The reproductive structures of angiosperms are formed in specialized and oftenshowy organs called flowers. In contrast to gymnosperms that produce seedsexposed in cones, angiosperms form seeds in an enclosed structure, the ripenedovary or fruit located in the center of the flower.The derivation of angiosperm meansseed in a box or case and is from the Greek words angio meaning box, case, orvessel and sperm meaning seed.ithin the embryo sac, onesperm combines with the egg nucleus to form a zygote and the second spermcombines with two other nuclei, called polar or endosperm nuclei, to form a fertilizedendosperm nucleus that divides mitotically to form endosperm (the nutritive tissue ofangiosperm seeds).