Syncytiotrophoblast
Encyclopedia
Syncytiotrophoblast is the epithelial covering of the placenta villous tree. It is a unique tissue in that it is a multi-nucleated, terminally differentiated syncytium, extending to 13m^2. It lacks proliferative capacity and instead is maintained by fusion of underlying cytotrophoblast cells.
It is the outer syncytial layer of the trophoblast
s and actively invades the uterine wall
.
They form the outermost fetal
component of the placenta (also known as 'syntrophoblast') and massively increase the surface area available for nutrient exchange between the mother and the fetus.
The syncytiotrophoblast secretes progesterone
in addition to human chorionic gonadotropin
(hCG) and human placental lactogen (HPL)
; hCG prevents degeneration of the corpus luteum
. Progesterone serves to maintain the integrity of the uterine lining and, until the syncytiotrophoblast is mature enough to secrete enough progesterone to support pregnancy (in the fourth month of embryonic development), it is aided by the corpus luteum graviditatis.
It is the outer syncytial layer of the trophoblast
Trophoblast
Trophoblasts are cells forming the outer layer of a blastocyst, which provide nutrients to the embryo and develop into a large part of the placenta. They are formed during the first stage of pregnancy and are the first cells to differentiate from the fertilized egg...
s and actively invades the uterine wall
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
.
They form the outermost fetal
Fetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...
component of the placenta (also known as 'syntrophoblast') and massively increase the surface area available for nutrient exchange between the mother and the fetus.
The syncytiotrophoblast secretes progesterone
Progesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...
in addition to human chorionic gonadotropin
Human chorionic gonadotropin
Human chorionic gonadotropin or human chorionic gonadotrophin is a glycoprotein hormone produced during pregnancy that is made by the developing embryo after conception and later by the syncytiotrophoblast .. Some tumors make this hormone; measured elevated levels when the patient is not...
(hCG) and human placental lactogen (HPL)
Human placental lactogen
Human placental lactogen , also called human chorionic somatomammotropin, is a polypeptide placental hormone. Its structure and function is similar to that of human growth hormone. It modifies the metabolic state of the mother during pregnancy to facilitate the energy supply of the fetus. HPL has...
; hCG prevents degeneration of the corpus luteum
Corpus luteum
The corpus luteum is a temporary endocrine structure in mammals, involved in production of relatively high levels of progesterone and moderate levels of estradiol and inhibin A...
. Progesterone serves to maintain the integrity of the uterine lining and, until the syncytiotrophoblast is mature enough to secrete enough progesterone to support pregnancy (in the fourth month of embryonic development), it is aided by the corpus luteum graviditatis.
