التعريف: Pseudocleavage begins just as the oocyte and sperm pronuclei appear at the anterior and posterior poles, respectively, of the elongated embryo. During this process, waves of cortical contraction sweep from posterior to anterior, and eventually become confined to the anterior membrane. A single large constriction, known as the pseudocleavage furrow, forms and subsequently regresses
التعريف: A taxon is Vulnerable when the best available evidence indicates that it meets any of the criteria A to E for Vulnerable, and it is therefore considered to be facing a high risk of extinction in the wild.
التعريف: A sheet of saline water separated from the open sea by sand or shingle banks. The sheet of water between an offshore reef, especially of coral and mainland. The sheet of water within a ring or horseshoe shaped atoll.