Befruktningens process

APC/C promotes transition from meiosis to mitosis during embryonic development.

Rapid cell division occurs without growth phases (cell shrinks) during the first 36 hours, resulting in the formation of two identical blastomeres (totipotent cells that can generate all types of tissue) up to the 8-cell stage.

During the 8-cell stage, compaction occurs, cells express e-cadherin, and junctions are formed, giving cells polarization. The collection of 16 cells is called a morula.

After the formation of 32 or more cells, a blastocyst is formed, consisting of a trophoblast (epithelial layer), a blastocoel (contains a sodium-potassium pump), and an inner cell mass (embryonic stem cells).

The inner cell mass is pluripotent, and hippo-signaling mediators facilitate cell position-dependent differentiation in the morula.

Hatching of the blastocyst is marked by the release of zonal pellucid (ZP) and the initiation of implantation. During implantation, trophoblasts bind to the endometrium via L-selectin, releasing enzyms and growth factors that lead to an inflammatory reaction, swelling of the endometrium, and increased blood vessel permeability.

The placenta is formed by cells derived from the inner cell mass and the inner trophoblasts. The placental tissue includes the corion (outer embryonic membrane), which forms villi with capillaries containing oxygenated fetal blood, and the intervillous space, which contains maternal blood.

The embryonic membranes are formed by the omformation of the inner cell mass into the embryonic disc, consisting of two layers: the epiblast facing the placenta (pluripotent cells that give rise to the amnion and later all germ layers) and the hypoblast, which gives rise to the extraembryonic membranes such as the chorion and the yolk sac.

Displacement of epiblast cells by the hypoblast through the primitive streak leads to the formation of the definitive endoderm and the overlying extraembryonic mesoderm, with the hypoblast disappearing.

The cells undergo epithelial-mesenchymal transition (EMT), and the notochord (a transient structure) sends signals to the ectoderm, causing it to thicken along the longitudinal axis.

The neural plate is formed and receives signals from the notochord, inducing somites to form along the lateral edges of the neural plate. The neural plate folds into the neural tube, creating a midline structure that eventually becomes the central nervous system and forms the brain and spinal cord.

The neural crest cells, derived from the neural plate, migrate and differentiate to form pigment cells, the peripheral nervous system, the adrenal glands, and various structures of the face and skull.

Mesoderm, formed from axial, paraxial, intermediate, and lateral regions, develops into various structures, including the axial skeleton, the limbs, the muscles, the heart, the circulatory system, and the skin.

The differentiation of mesoderm depends on the region of the primitive streak through which the cells ingress. Somites, formed from paraxial mesoderm, give rise to the skeletal muscles and the vertebral column, and they are called the primitive segments.

APC/C promotes transition from meiosis to mitosis during embryonic development.

Rapid cell division occurs without growth phases (cell shrinks) during the first 36 hours, resulting in the formation of two identical blastomeres (totipotent cells that can generate all types of tissue) up to the 8-cell stage.

During the 8-cell stage, compaction occurs, cells express e-cadherin, and junctions are formed, giving cells polarization. The collection of 16 cells is called a morula.

After the formation of 32 or more cells, a blastocyst is formed, consisting of a trophoblast (epithelial layer), a blastocoel (contains a sodium-potassium pump), and an inner cell mass (embryonic stem cells).

The inner cell mass is pluripotent, and hippo-signaling mediators facilitate cell position-dependent differentiation in the morula.

Hatching of the blastocyst is marked by the release of zonal pellucid (ZP) and the initiation of implantation. During implantation, trophoblasts bind to the endometrium via L-selectin, releasing enzyms and growth factors that lead to an inflammatory reaction, swelling of the endometrium, and increased blood vessel permeability.

The placenta is formed by cells derived from the inner cell mass and the inner trophoblasts. The placental tissue includes the corion (outer embryonic membrane), which forms villi with capillaries containing oxygenated fetal blood, and the intervillous space, which contains maternal blood.

The embryonic membranes are formed by the omformation of the inner cell mass into the embryonic disc, consisting of two layers: the epiblast facing the placenta (pluripotent cells that give rise to the amnion and later all germ layers) and the hypoblast, which gives rise to the extraembryonic membranes such as the chorion and the yolk sac.

Displacement of epiblast cells by the hypoblast through the primitive streak leads to the formation of the definitive endoderm and the overlying extraembryonic mesoderm, with the hypoblast disappearing.

The cells undergo epithelial-mesenchymal transition (EMT), and the notochord (a transient structure) sends signals to the ectoderm, causing it to thicken along the longitudinal axis.

The neural plate is formed and receives signals from the notochord, inducing somites to form along the lateral edges of the neural plate. The neural plate folds into the neural tube, creating a midline structure that eventually becomes the central nervous system and forms the brain and spinal cord.

The neural crest cells, derived from the neural plate, migrate and differentiate to form pigment cells, the peripheral nervous system, the adrenal glands, and various structures of the face and skull.

Mesoderm, formed from axial, paraxial, intermediate, and lateral regions, develops into various structures, including the axial skeleton, the limbs, the muscles, the heart, the circulatory system, and the skin.

The differentiation of mesoderm depends on the region of the primitive streak through which the cells ingress. Somites, formed from paraxial mesoderm, give rise to the skeletal muscles and the vertebral column, and they are called the primitive segments.