Introduction Flashcards
Embryology
The study of development from fertilization to birth
Fertilization
The fusion of the sperm and “egg”
Cleavage
Early divisions in the embryo
Blastulation
creation of a hollow cavity
Gastrulation
migration of cells to form major tissue layers
Organogenesis
development of organs
Developmental Events
Fertilization, Cleavage, Blastulation, Gastrulation, Organogenesis
Developmental Stages
Embryo, Fetus, Newborn
Early embryo
1st three weeks, dated by fertilization age. Fertilization to gastrulation. Cells created, but organs not yet forming.
Embryo organogenesis
Shape of structures change. Weeks 4-8. Organs form.
Fetus
9 weeks - birth. Organs have mature shape, and develop further functions.
Conception
beginning of life. Starts at fertilization
Pregnancy
the condition of a woman carrying developing offspring in her body. Lasts from fertilization to birth.
Conceptus
the zygote/embryo/fetus
Embryo/fetus proper
part of embryo/fetus that contribute to structures that remain after birth
Extraembryonic/extrafetal membranes
parts of embryo/fetus that don’t remain after birth
Fertilization age
age of conceptus. Starts at fertilization. Used by embryologists
Menstrual age
fertilization age + 2 weeks. imprecise
Gestational age
either fertilization or menstrual age
Trimesters
three three month periods dated from menstrul age. Used by medical professionals
Carnegie Stages
Developmental stages in vertebrates. Only covers embryonic (not fetal) development. Categorized by visible structures, not days or size.
