Human Embryo: Fertilisation to Implantation

Also called

embryo development · human embryo development · early embryonic development · fertilisation · fertilization · zygote · cleavage · blastomere · morula · blastocyst · blastula · trophoblast · inner cell mass · blastocoel · zona pellucida · hatching · implantation · embryo implantation · oviduct · fallopian tube · ampulla · endometrium · placenta formation · human reproduction · class 12 human reproduction · NCERT human reproduction

Topics

• Fertilisation normally takes place in the ampulla of the oviduct (fallopian tube).
• Only one sperm fertilises the egg; the egg and sperm pronuclei come together in the zygote.
• Cleavage is a series of mitotic divisions: 2, 4, 8, 16 cells (blastomeres).
• During cleavage the cell number rises but the cells get smaller…
• A morula is a solid ball of 8 to 16 or more blastomeres; it reaches the uterus at about this stage.
• A blastocyst has an outer trophoblast, an inner cell mass at one side and a fluid-filled cavity, the blastocoel…
• The blastocyst hatches from the zona pellucida before it can implant.
• Implantation happens in the endometrium of the uterus, usually in the upper part of the body of the uterus…
• The trophoblast attaches to and invades the endometrium; it forms the embryo's side of the placenta (chorion…
• The inner cell mass gives rise to the embryo proper (via the epiblast) and to the amnion and yolk sac linings.
• Mother's blood fills spaces next to the trophoblast; the embryo's blood stays in its own vessels and does not mix with…

About this model

A GLB file of about 1778 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Uterus outer surface and left ovary: HuBMAP Human Reference Atlas, CCF 3D Reference Object Library (Kristen Browne et al., NIH/NIAID; derived from the NLM Visible Human Project), humanatlas.io, CC BY 4.0. Re-oriented, cut in a frontal section, simplified; right ovary is a mirrored copy. Zona pellucida shape: "Human egg cell" (isolated zona pellucida) by Julio Hidalgo, Tactiles, https://tactiles.eu/tactiles/human-egg-cell/, CC BY-SA 4.0. Trimmed to a half shell, simplified, mirrored and recoloured. Cavity, endometrium, oviducts, fimbriae, cells, blastocyst, close-ups, markers, stage cards and animation were made for Lably. This model is shared under CC BY-SA 4.0. | CC BY-SA 4.0. Contains the zona pellucida shape from Tactiles (CC BY-SA 4.0) and uterus/ovary surfaces from the HuBMAP Human Reference Atlas (CC BY 4.0), so this model is shared under CC BY-SA 4.0.

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