introduction to developmental biology

• What are the three primary germ layers formed during gastrulation?

  • Epiblast
  • Hypoblast
  • Extraembryonic mesoderm

  
• What is the cavity that surrounds the epiblast?

  Amniotic cavity

  
• What is the name of the trophoblast cell layer that is multinucleated?

  Syncytiotrophoblast

  
• What is the name of the trophoblast cell layer that is composed of individual cells?

  Cytotrophoblast

  
• What is the definitive yolk sac primarily responsible for?

  Providing nutrition to the embryo during development

  
• What aspect of embryonic development is depicted in the image?

  Early embryonic development and the formation of basic anatomical structures

  
• How does the visualization technique used in the image aid in understanding embryonic development?

  It provides a detailed and clear view of the internal structures, allowing for easier identification and study of developmental stages

  
• What is shown in the provided images?

  The images show different stages of early embryonic development.

  
• What types of scientific fields might this image relate to?

  Genetics, molecular biology, or microscopy techniques

  
• What is developmental biology?

  • The study of the transient stages between egg and birth
  • How the egg produces an adult and the adult produces an egg and embryo
• Why study developmental biology?

  • Understand how the body plan is formed
  • Learn about anatomy more easily
  • Treat birth defects as vets
  • Learn about embryonic stem cells and their future in medicine
  • Understand cancer as essentially uncontrolled development
• What does developmental biology study about the transient stages between egg and birth?

  The transient stages between egg and birth
• What is one aspect studied in developmental biology regarding the egg?

  How the egg produces an adult
• What processes related to the adult are studied in developmental biology?

  How the adult produces an egg and an embryo
• What will you study in the Overview of the Week for developmental biology?

  • The basic processes that take the single-cell egg to the embryo
  • Through lectures, directed learning sessions, and practical sessions
  • Requires attending practical sessions with a lab coat to work with chick eggs
  • Includes topics like egg allergies
• What is the first process studied in the generation of cells?

  Growth
• What process is defined as the generation of different cells?

  Differentiation
• What term refers to the generation of tissues, organs, and the whole body?

  Morphogenesis
• What are model organisms used for in developmental biology studies?

  • Easy to breed
  • Easy to maintain in a lab
  • Have some similarity to humans
  • Short lifespan (invertebrates)
  • Easy to handle large numbers (invertebrates)
  • Easily mutated (invertebrates)
  • Genome sequenced (invertebrates)
  • Ideal genetic models (invertebrates)
  • Develop external to mother (vertebrates - anamniotes)
  • Large eggs (vertebrates - anamniotes)
  • Transparent – good for anatomical development (vertebrates - anamniotes)
  • Easily mutated (vertebrates - anamniotes)
  • Sequenced genomes (vertebrates - anamniotes)
  • Some develop external to mother (vertebrates - amniotes)
  • Mammalian transgenics (knockouts) (vertebrates - amniotes)
  • Easily experimentally manipulated (vertebrates - amniotes)
  • Closer to humans than anamniotes (vertebrates - amniotes)
  • Sequenced genomes (vertebrates - amniotes)
• Why is it necessary to use a combination of model organisms in developmental biology studies?

  • No single model is sufficient
  • Combining models provides a broader understanding of development
  • Allows the study of species differences and general development principles
  • Key to understanding changes in the body plan over time, which is relevant to evolution
• What are the first events of life in developmental biology?

  • Fertilization
  • Formation of the early embryo
• At what stage does fertilization begin in an organism's life journey?

  Fertilization is where the journey of life begins
• What must occur for fertilization to take place?

  Two germ cells must meet and fuse to form a zygote
• Where do primordial germ cells form?

  • In the ovary or testis
• What is the ploidy of primordial germ cells when they form?

  Diploid $(2n)$
• What process do primordial germ cells undergo to form sperm and egg?

  Meiosis
• What is the ploidy of sperm and egg cells?

  Haploid $(1n)$
• What is fertilisation?

  The entry of sperm into the oocyte leading to the formation of a zygote
• What becomes impenetrable after fertilization to prevent polyspermy?

  The oocyte
• What type of zygote is formed when two haploid cells fuse?

  A diploid zygote
• What cellular process is initiated after fertilisation?

  Mitotic cell division
• At what cell stage does the morula form?

  16-cell stage
• What occurs during the cleavage stage of embryonic development?

  • Cells divide and become smaller
  • These cells are called blastomeres
  • Each cell touches the zona pellucida
  • At the 16-cell stage, the embryo becomes a morula
• What do the inner core cells of the morula become?

  The embryo proper
• How are cells organised in the morula?

  • Inner core of cells
  • Superficial layer of cells
• What do the superficial layer cells of the morula become?

  Extra-embryonic membranes
• What forms during the blastocyst stage?

  • Fluid pumped into the embryo by cells on the outside to form the blastocyst cavity
  • Inner cells = Inner cell mass (embryonic stem cells)
  • Superficial layer cells = trophoblasts
  • This stage is also called a ‘blastula’
• What does the blastocyst do during hatching?

  Breaks out of the zona pellucida and starts to grow
• What influences the growth rate of the blastocyst?

  Species dependence
• What occurs during implantation in mammals?

  The hatched blastocyst implants into the uterine wall to receive nutrition and excrete waste