Qcm 1 D'embryologie

The correct answer is "Un embryon triblastique." Gastrulation is a key process during embryonic development where the single-layered blastula transforms into a three-layered structure called the gastrula. The gastrula consists of three primary germ layers: ectoderm, mesoderm, and endoderm. These layers give rise to various tissues and organs in the developing embryo. Therefore, the result of gastrulation is the formation of a triblastic embryo.

The correct answer is Blastocyste. La blastula des mammifères est appelée blastocyste. La blastocyste est une étape du développement embryonnaire des mammifères qui se produit après la division de la morula. Elle est caractérisée par la formation d'une cavité remplie de liquide appelée blastocèle et par la différenciation des cellules en deux types : le trophoblaste, qui formera le placenta, et la masse cellulaire interne, qui se développera en embryon.

The correct answer is "Externe : le syncytiotrophoblaste et interne ; le cytotrophoblaste". The trophoblast is composed of two layers: the outer syncytiotrophoblast and the inner cytotrophoblast. The syncytiotrophoblast is responsible for implantation and hormone production, while the cytotrophoblast is involved in cell division and differentiation.

The correct answer is "Ectodermique". The neural plate, which later develops into the neural tube and eventually forms the central nervous system, originates from the ectoderm during embryonic development. The ectoderm is one of the three primary germ layers in the early embryo, and it gives rise to various tissues and structures, including the nervous system, skin, and hair.

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The correct answer is that the primitive streak marks the beginning of gastrulation and the cells of the epiblast migrate towards the primitive streak before invagination.

Partial segmentation only affects a part of the egg. It does not involve the entire egg. Partial segmentation is found in telolecithal and centrolecithal eggs.

The given answer is correct because it states that Spina bifida is a congenital malformation in humans and it is a defect in the closure of the neural tube in the caudal (lower) part of the body. Spina bifida is a condition where the spinal cord and the surrounding bones do not form properly, leading to various neurological and physical disabilities.

The correct answer is "Ectophyle ou hypoblaste et entophyle ou épiblaste." This answer is correct because it states that the secondary blastula is composed of ectophyle or hypoblaste and entophyle or épiblaste. The ectophyle or hypoblaste refers to the outer layer of cells in the blastula, while the entophyle or épiblaste refers to the inner layer of cells. Therefore, this answer accurately describes the composition of the secondary blastula.

The correct answer is "L’œuf se segmente d’autant plus vite qu’il est moins chargé de vitellus" and "La segmentation totale se rencontre dans les œufs oligolécithes et hétérolécithes". This means that the speed of segmentation in an egg is faster when it has less yolk, and total segmentation occurs in eggs with a small amount of yolk (oligolécithes) and unevenly distributed yolk (hétérolécithes).