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Period: 2019 BCE to
Preimplantation Period
*Ovum and sperm penetrates the egg
*Chromosomes from sperm and egg join together
* Mitosis occurs after fertilization and the cells turn into blastocyctes. -
Period: to
Embryonic Period
*Induction
*Proliferation
*Differentiation
*Morphogenesis
*Maturation -
Period: to
Second Week of Prenatal Development
*Blastocyst grows due to increased proliferation.
* creates embryonic cell layers within blastocyst.
*Bilaminar embryonic disc developes from blastocyst. -
Third Week of Prenatal Development
Conceptus implantion in the uterus wall is complete and trophoblast cells continue to invade uterine wall in the process of early placentation (villi formation). Within the conceptus, gastrulation converts the bilaminar embryo into the trilaminar embryo (ectoderm, mesoderm, endoderm). Morphological changes include an epithelial to mesenchymal cell transition and folding of the embryonic disc. Carnegie stages 7 to 9 covers this period of human embryo development. -
Fourth and Fifth Week of Prenatal Development
Around the fourth week, the head begins to form quickly followed by the eyes, nose, ears, and mouth. The cardiovascular system is where the earliest activity begins as the blood vessel that will become the heart start to pulse. During the fifth week, buds that will form the arms and legs appear -
Period: to
Fetal Period
*Physiological processes of maturation of individual tissue types and organs.
*Final Palate forms and nasal cavity is completed by 12th week
*Fetal heartbeat and movements at the end of the fourth month -
Period: to
Sixth Week of Prenatal Development
*Maxillary processes fuse together forming the upper lip.
*The medial nasal processes contribute to the philtrum of the nose. -
Period: to
Seventh Week of Prenatal Development
*upper lip is completed
*secondary palate is formed
*Muscle cells of the mesoderm differentiate and migrate to mandibular muscle. -
Period: to
Eighth Week of Prenatal Development
*All facial structures are complete -
Period: to
Birth