embryology

• What is the branch of biology concerned with the development of organisms?

  Embryology
• How long does embryonic development in humans last?


  Eight weeks
• What term is used to describe the embryo after the eighth week of development?

  Fetus
• What is the normal period of gestation in humans?


  About nine months or 40 weeks
• How does embryology assist with women's reproductive health?


  It helps understand issues leading to developmental defects and malformations
• What are the key stages of embryonic development from fertilization to birth?

  • Week 1: Fertilization to Implantation
  • Week 2: Bilaminar Germ Disc
  • Week 3: Gastrulation and Trilaminar Germ Disc
  • Weeks 3-8: Organogenesis (embryonic period)
  • Week 8 to Birth: Fetal Period
• What is formed during the first week of embryonic development?


  Two-cell zygote and morula
• What happens approximately four days after fertilization?

  A blastocyst is formed
• What are the two cell layers of the blastocyst?


  Inner cell mass (embryoblast) and outer cell mass (trophoblast)
• What is the significance of the bilaminar germ disc?


  It forms the two cell layers: epiblast and hypoblast
• What forms during week 2 of embryonic development?


  The bilaminar germ disc
• What is the role of the primitive streak during gastrulation?


  It gives rise to mesenchyme and forms three cell layers
• What are the three germ layers formed during gastrulation?


  Ectoderm, mesoderm, and endoderm
• What does the ectoderm develop into?


  Nervous system, epidermis, and sensory epithelium
• What does the mesoderm give rise to?


  Muscle, connective tissue, and blood vessels
• What is the function of the endoderm?


  It forms the linings of the digestive and respiratory tracts
• What processes occur during the embryonic period (weeks 3-8)?

  • Neurulation: development of the central nervous system
  • Organogenesis: development of major organ systems
  • Formation of somites and the musculoskeletal system
  • Development of the intraembryonic coelom (body cavity)
• What is the result of the longitudinal and transverse folding of the trilaminar disc?


  It converts the flat trilaminar disc into a C-shaped, cylindrical embryo
• What happens to the yolk sac during embryo folding?


  It becomes incorporated into the embryo as the primitive gut
• What is the significance of the dorsal mesentery after folding?


  It suspends the gut tube within the embryo
• What are the stages of limb development?


  • Onset of arm bud development: 27 days
  • Well-developed arm bud: 28-30 days
  • Elongation of arm bud: 34-36 days
  • Formation of hand paddle: 36-38 days
  • Onset of finger separation: 38-40 days
  • Full separation of fingers: 50-52 days
• What is the role of paraxial mesoderm in development?


  It forms somites, which are axial musculoskeletal elements
• What is the difference between prenatal and postnatal circulatory patterns?


  They differ in the pathways and structures involved in circulation
• What happens at the end of organogenesis?


  All organ systems are formed but need further maturation
• What are the stages of postnatal development?


  • Infancy: approx. first year post-birth
  • Childhood: period between infancy and puberty
  • Puberty: between 8-13 years of age
  • Adulthood: between 18-21 years of age
• What is the significance of the notochord during development?


  It induces the overlying ectoderm to form the neural plate
• What is the role of the connecting stalk in embryonic development?


  It forms the primitive umbilical cord
• What is the function of the chorionic cavity?


  It is derived from extraembryonic mesoderm and supports the embryo
• What is the primary function of the trophoblast?


  It aids in implantation into the uterine wall
• How does the embryonic disc develop into the embryonic body?


  Through folding and cell differentiation
• How does the development of the musculoskeletal system differ between paraxial and lateral plate mesoderm?


  Paraxial mesoderm forms somites, while lateral plate mesoderm forms appendicular elements
• What is the significance of the primitive gut in embryonic development?


  It is formed from the yolk sac and is essential for nutrient absorption
• What is the first organ system to start functioning during development?

  The cardiovascular system
• What is the role of the amniotic cavity during development?


  It provides a protective environment for the developing embryo
• How does the process of maturation and development continue after organogenesis?


  It continues throughout the fetal period and into adulthood
• What is the primary source of skeletal muscle development?

  Mesenchyme surrounding the developing bones
• What happens to muscle masses during limb development?


  They separate into dorsal (extensor) and ventral (flexor) components
• What is the significance of pharyngeal arches in development?


  They are involved in the development of the head and face
• How does the development of the head and face occur?

  Through the formation of pharyngeal arches and pouches
• What is the source of the axial skeleton?

  Paraxial mesoderm (somites)