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1 de mai. de 2024 · Evolution of the amniotic egg gives rise to the amniotes, tetrapods that can reproduce on land and lay shelled eggs on dry land. They did not need to return to water for reproduction nor breathing.
Há 2 dias · Most reptiles lay amniotic eggs covered with leathery or calcareous shells. An amnion (5), chorion (6), and allantois (8) are present during embryonic life. The eggshell (1) protects the crocodile embryo (11) and keeps it from drying out, but it is flexible to allow gas exchange.
30 de abr. de 2024 · One question that often arises is whether turtles lay amniotic eggs. The short and bold answer is: Yes, turtles do have amniotic eggs. Similar to other reptiles, turtles possess a specialized egg structure that helps protect and nourish the developing embryos inside.
2 de mai. de 2024 · placenta, in zoology, the vascular (supplied with blood vessels) organ in most mammals that unites the fetus to the uterus of the mother. It mediates the metabolic exchanges of the developing individual through an intimate association of embryonic tissues and of certain uterine tissues, serving the functions of nutrition, respiration, and ...
- The Editors of Encyclopaedia Britannica
By “egg” I am assuming you mean the shelled, amniotic, external egg. (This excludes much earlier appearances, like the oviparous armored fish of a half a billion years ago.) That seed-like sort of egg evolved among the amniotes, vertebrates who had ventured onto the land.
Há 4 dias · Amniotic eggs, however, have internal membranes that allow the developing embryo to breathe but keep water in. Hence, amniotes can lay eggs on dry land, while amphibians generally need to lay their eggs in water. The first amniotes apparently arose in the Pennsylvanian subperiod of the Carboniferous.
3 de mai. de 2024 · The amniotic fluid index (AFI) is an estimate of the amniotic fluid volume in a pregnant uterus. It is part of the fetal biophysical profile . Technique. the uterus is divided into four imaginary quadrants with the linea nigra and a mediolateral line running through the umbilicus acting as the vertical and the horizontal axes respectively.
