Embryonic Development: Morula and Blastula Stages

Embryonic Development

Morula Stage (Days 3-4)

• A solid ball of cells formed by continuous cell division
• Composed of 16-32 cells
• Cells are compacted and separated by small gaps
• No distinct shape or structure

Blastula Stage (Days 5-6)

• Fluid-filled cavity (blastocoel) forms within the morula
• Cells flatten and spread to form the blastoderm
• Distinct inner cell mass (ICM) and trophectoderm (TE) layers emerge
• ICM will develop into the embryo, while TE will form the placenta

Gastrulation Stage (Days 7-10)

• Complex cellular movements resulting in the formation of three primary germ layers:
  1. Ectoderm: gives rise to skin, nervous system, and sensory organs
  2. Mesoderm: forms muscles, bones, and connective tissue
  3. Endoderm: develops into lining of digestive system and other internal organs
• Gastulation establishes the basic body plan and organization of tissues

Organogenesis Stage (Days 10-8 weeks)

• Germ layers differentiate into specific tissues and organs
• Major organ systems begin to form, including the nervous, circulatory, and digestive systems
• Embryo undergoes rapid growth and development
• Organogenesis sets the stage for further development and refinement of organ systems

Fetal Development Stage (8 weeks-birth)

• Continued growth and refinement of organ systems
• Development of sensory organs and limbs
• Maturation of nervous system and brain function
• Preparation for life outside the womb

Embryonic Development

Morula Stage (Days 3-4)

• A solid ball of cells is formed through continuous cell division, comprising 16-32 cells
• Cells are compacted and separated by small gaps, but have no distinct shape or structure

Blastula Stage (Days 5-6)

• A fluid-filled cavity called the blastocoel forms within the morula
• Cells flatten and spread to form the blastoderm, with distinct inner cell mass (ICM) and trophectoderm (TE) layers emerging
• The ICM will develop into the embryo, while the TE will form the placenta

Gastrulation Stage (Days 7-10)

• Complex cellular movements result in the formation of three primary germ layers
• The three primary germ layers are:
  • Ectoderm: gives rise to skin, nervous system, and sensory organs
  • Mesoderm: forms muscles, bones, and connective tissue
  • Endoderm: develops into the lining of the digestive system and other internal organs
• Gastrulation establishes the basic body plan and organization of tissues

Organogenesis Stage (Days 10-8 weeks)

• Germ layers differentiate into specific tissues and organs
• Major organ systems begin to form, including the nervous, circulatory, and digestive systems
• The embryo undergoes rapid growth and development
• Organogenesis sets the stage for further development and refinement of organ systems

Fetal Development Stage (8 weeks-birth)

• Continued growth and refinement of organ systems
• Development of sensory organs and limbs
• Maturation of nervous system and brain function
• Preparation for life outside the womb