Animal Development II: Gastrulation & Organogenesis

Study Notes

Animal Development II: Gastrulation and Organogenesis

Gastrulation is the rearrangement of cells in the blastula to create embryonic tissue layers, resulting in a gastrula
Organogenesis is the process of organ and tissue formation through cell division and differentiation, culminating in morphogenesis (shape and body organization).
Four general stages in early animal development: fertilization, cleavage, gastrulation, and organogenesis.
Three crucial outcomes of gastrulation: formation of germ layers (endoderm, mesoderm, ectoderm), formation of the archenteron (embryonic gut), and the appearance of body axes.
Germ layers develop into tissues and organ systems.
Gastrulation involves dramatic cell movements across and inside the embryo.
Triploblasts (animals with three germ layers) have cells moving into the blastocoel during gastrulation
Diploblasts (animals with two germ layers) have radial symmetry and fewer tissue types than triploblasts.
Epithelial tissue comprises tightly packed cells that line body cavities and cover surfaces, forming barriers and enabling nutrient absorption.
Connective tissue supports and connects tissues; common types include loose connective tissue, dense connective tissue, adipose tissue, bone, cartilage, and blood.
Muscle tissue enables movement and functions in contraction via actin and myosin
Three types of muscle tissue: smooth, skeletal, and cardiac.
Nervous tissue senses stimuli and transmits information, composed of neurons and glial cells.
Four extra-embryonic tissues in amniotes: amnion, chorion, allantois, and yolk sac, with varying functions.
The amnion protects the embryo.
The chorion facilitates oxygen and carbon dioxide exchange.
The allantois stores waste and aids in respiration.
The yolk sac encloses nutrients.
Placental mammals have internalized the egg, using structures like the chorion to enable gas exchange between mom and fetus and the amnion for aqueous development.
Chorion, amnion, yolk sac and allantois work together, facilitating nutrient and waste transport in mammals' internal development
Organogenesis involves germ layer differentiation into various organs.
The nervous system develops from ectoderm.
Notochord (mesoderm-derived) is a rod-shaped structure that signals neural plate cells to fold into a neural tube, developing into the brain and spinal cord.
Hox genes play a crucial role in determining the body plan and segment identity in animals, through controlling large numbers of other genes through transcription factors.

Additional Notes

Multiple stages of chick development are key to understand the timeline of embryonic development
The text refers to figures, but they are not included in this summary.
Diagrams/figures would provide a better understanding of the processes.