Chapter 3.1 Overview of Embryology Flashcards
Embryology deals with the developmental events that occur during the
Prenatal period
The prenatal period is the first
38 weeks of human development that begin with the fertilization of the secondary oocyte and end with birth
The prenatal period is broken down into shorter periods
- The pre-embryonic period
- The embryonic period
- The fetal
The pre-embryonic period is
The first 2 weeks of development (the first 2 weeks after fertilization), when the single cell produced by fertilization (the zygote) becomes a spherical, multicellular structure (a blastocyst). This period ends when the blastocyst implants in the lining of the uterus
The embryonic period includes
The third through eighth weeks of development. Time during which rudimentary versions of the major organ systems appear in the body, which is now called the embryo
Includes the remaining 30 weeks of development prior to birth, when the organism level is called a fetus. During this period, the fetus continues to grow, and its organs increase in complexity
The fetal period
The developmental processes that occur in the pre-embryonic and embryonic periods are known collectively as
Embryogenesis
Embryogenesis and its stages are separated into
Cleavage, gastrulation, and organogenesis
The zygote divides by mitosis to form a multicellular structure called a blastocyst
Cleavage
The blastocyst cells form three primary germ layers, which are the basic cellular structures from which all body tissues develop
Gastrulation
The three primary germ layers arrange themselves in ways that give rise to all organs in the body
Organogenesis
Following birth, an individual spends a great portion of his or her life undergoing
Maturation
During maturation the body grows and develops, and these organs become mature
Sex organs
The sex organs (ovaries in the female, testes in the male) then begin to produce sex cells, or gametes through a process called
Gametogenesis
