The trophoblast (from Greekthrephein: to feed) is considered to be the first of all embryonic annexes. It secretes hCG in order to maintain progesterone secretion and sustain a pregnancy. Embryos (and one tadpole) of the wrinkled frog (Rana rugosa). ... HCG may stand for Human chorionic gonadotropin (usually abbreviated with a lowercase h: hCG) H computer graphics (pornographic drawings in H games) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...
The invasion of a specific type of trophoblast (extravillous trophoblast) into the maternal uterus is a vital stage in the establishment of pregnancy. Failure of the trophoblast to invade sufficeintly may be important in the development of some cases of pre-eclampsia.
The cells of the morula are at first closely aggregated, but soon they become arranged into an outer or peripheral layer, the trophoblast, which does not contribute to the formation of the embryo proper, and an inner cell-mass, from which the embryo is developed.
Fluid collects between the trophoblast and the greater part of the inner cell-mass, and thus the morula is converted into a vesicle, the blastodermic vesicle (Fig.
The inner cell-mass remains in contact, however, with the trophoblast at one pole of the ovum; this is named the embryonic pole, since it indicates the situation where the future embryo will be developed.
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