Chapter 21: Development of Multicellular Organisms

Development

It refers to the process by which a single-celled zygote transforms into a complex multicellular organism with specialized tissues and organs.

Embryogenesis

It is the stage of development in which the zygote undergoes rapid cell divisions and differentiation to form the basic body plan of the organism.

Organogenesis

Cells organize into precise patterns and structures, forming organs such as the heart, lungs, brain, and limbs.

Cell migration

It is essential for shaping tissues and organs during development. Cells move in a directed manner, guided by chemical gradients and adhesive interactions.

Pattern formation

It refers to the process by which spatially ordered structures and arrangements arise during development, resulting in the diverse patterns observed in organisms.

Morphogens

They are signaling molecules that form concentration gradients, and their distribution provides spatial cues for cells to adopt specific fates and organize into patterns.

Reaction-diffusion systems

It proposes that the interaction between diffusible substances can generate spatial patterns through their diffusion and reaction kinetics.

Developmental timing

It refers to the precise coordination and control of developmental events, ensuring that they occur in the correct sequence and at the appropriate time during an organism's development.

Morphogenesis

It refers to the process by which cells and tissues organize and shape themselves to form the intricate structures and organs of an organism during development.

Cell division

It contributes to tissue growth and expansion, increasing the number of cells and providing the material for morphogenetic events.

Cell differentiation

It involves the acquisition of specific cell fates and functions, leading to the formation of distinct tissue types.

Cell adhesion

It plays a crucial role in shaping tissues and organs during morphogenesis.

Cell migration

It is essential for rearranging cells and tissues, allowing them to establish proper connections and generate complex architectures.

Neurulation

It is the process by which the neural tube is formed, giving rise to the central nervous system.

Organogenesis

It involves the formation and differentiation of specific organs and tissues from germ layers, leading to the development of complex structures such as the heart, lungs, liver, and limbs.

Gastrulation

It involves the rearrangement of cells into three germ layers (ectoderm, mesoderm, and endoderm), establishing the body plan of the embryo.

Growth

It refers to the increase in size, mass, and complexity of an organism over time.

Cell division

It is the primary mechanism of growth, allowing for the increase in cell number and tissue expansion.

Cell differentiation

It accompanies growth, as undifferentiated cells acquire specialized functions and contribute to tissue organization and complexity.

Cell enlargement, or cell hypertrophy

It involves an increase in cell size through the accumulation of cellular components and organelles.

Extracellular matrix (ECM)

It plays a crucial role in growth by providing structural support, organizing tissues, and regulating cellular behavior.

Neural development

It refers to the process by which the nervous system, including the brain and spinal cord, forms and matures during embryonic and postnatal stages.

Neurogenesis

the production of new neurons, occurs in specific regions of the developing brain, such as the ventricular zone and subventricular zone.

Synaptogenesis

It is the process by which synapses, the specialized junctions between neurons, are formed. It involves the precise alignment of pre- and postsynaptic elements.

Synaptic refinement

It occurs through a combination of activity-dependent mechanisms and synaptic pruning, ensuring the formation of functional neural circuits.

Myelination

the process of insulating axons with a myelin sheath, enhances signal transmission and promotes efficient neural communication.