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The face and neck development of the human embryo refers to the development of the structures from the third to eighth week that give rise to the future head and neck.They consist of three layers, the ectoderm, mesoderm and endoderm, which form the mesenchyme (derived form the lateral plate mesoderm and paraxial mesoderm), neural crest and neural placodes (from the ectoderm). [1]
[11]: 165 This is a horseshoe-shaped area near to the head of the embryo. By day 19, following cell signalling , two strands begin to form as tubes in this region, as a lumen develops within them. These two endocardial tubes grow and by day 21 have migrated towards each other and fused to form a single primitive heart tube, the tubular heart .
The embryo becomes embedded in the endometrium in a process called implantation. In most successful pregnancies, the embryo implants 8 to 10 days after ovulation. [7] The embryo, the extra-embryonic membranes, and the placenta are collectively referred to as a conceptus, or the "products of conception".
The embryo measures 4 mm (1 ⁄ 8 in) in length and begins to curve into a C shape. The heart bulges, further develops, and begins to beat in a regular rhythm. Septum primum appears. [1] Pharyngeal arches, grooves which will form structures of the face and neck, form. The neural tube closes. The ears begin to form as otic pits. Arm buds and a ...
Drawing of the head of a four-week-old human embryo. From Gray's Anatomy. Embryo drawing is the illustration of embryos in their developmental sequence. In plants and animals, an embryo develops from a zygote, the single cell that results when an egg and sperm fuse during fertilization. In animals, the zygote divides repeatedly to form a ball ...
1 - morula, 2 - blastula 1 - blastula, 2 - gastrula with blastopore; orange - ectoderm, red - endoderm. Embryology (from Greek ἔμβρυον, embryon, "the unborn, embryo"; and -λογία, -logia) is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses.
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The cervical sinus is a structure formed during embryonic development.It is a deep depression found on each side of the neck.It is formed as the second pharyngeal arch (hyoid arch) grows faster than the other pharyngeal arches, so they become covered.