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The placenta (pl.: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation.It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate maternal and fetal circulations, and is an important endocrine organ, producing hormones that regulate both maternal and fetal ...
Menstrual cycle The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that makes pregnancy possible. The ovarian cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone. The uterine cycle governs the preparation and maintenance of the lining of the ...
The placenta can be defined as an organ formed by the sustained apposition or fusion of fetal membranes and parental tissue for physiological exchange. [1] This definition is modified from the original Mossman (1937) [2] definition, which constrained placentation in animals to only those instances where it occurred in the uterus.
Hormones are synthesized in certain organs, including the ovaries, placenta, and pituitary gland. [1] These hormones have essential functions in pregnancy test, maintaining the uterine lining, fetal development, preventing premature labor, and the initiation and support of labor.
The function of these shunts is to bypass the lungs and maintain proper circulation to important fetal tissue. In the fetal stage, the lungs fill with fluid and collapse because the fetus is within the amniotic sac and the placenta is providing the oxygen it needs to grow.
Trophoblasts are specialized cells of the placenta that play an important role in embryo implantation and interaction with the decidualized maternal uterus. [5] The core of placental villi contain mesenchymal cells and placental blood vessels that are directly connected to the fetus’ circulation via the umbilical cord.
If implantation occurs, the corpus luteum will continue to produce progesterone for eight to twelve weeks, after which the placenta takes over this function. [6] In the absence of fertilization, hCG is not produced and the corpus luteum will atrophy in 10–12 days (Luteolysis or luteal regression).
The endometrium is the innermost lining layer of the uterus, and functions to prevent adhesions between the opposed walls of the myometrium, thereby maintaining the patency of the uterine cavity. [12] During the menstrual cycle or estrous cycle, the endometrium grows to a