Organogenesis and Germ Layer Derivates | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Derivatives of Different Embryonic Layers:

(a) Ectodermal Derivatives:

1. Stomodeal Part of Mouth:

   • Originates from the outermost embryonic layer (ectoderm).

2. Pituitary:

   • The pituitary gland, a crucial endocrine organ.

3. Salivary Glands, Tongue:

   • Structures related to the mouth and digestion.

4. Central Nervous System:

   • Brain and spinal cord development.

5. Organs of Special Senses:

   • Eyes, ears, and other sensory organs.

6. Adrenals:

   • Adrenal glands, part of the endocrine system.

7. Lens of the Eye, Internal Ear:

   • Components of the eye and ear.

8. Epidermis of Skin, Nails, Hair, Sebaceous Glands:

   • Skin layers, nails, hair, and oil glands.

(b) Mesodermal Derivatives:

1. Spleen:

   • An organ involved in the immune system.

2. Organs of Urogenital Systems:

   • Structures related to the urinary and reproductive systems.

3. Skeletal System:

   • Bones and connective tissues.

4. Dermis or Corium:

   • The deeper layer of skin.

5. Vertebral Column, Sternum:

   • Backbone and breastbone.

(c) Endodermal Derivatives:

1. Primary Tissues of Digestive Tract:

   • Initial structures of the digestive system.

2. Pharyngeal Part of the Mouth:

   • Part of the throat and mouth.

3. Thymus:

   • An organ involved in the immune system.

4. Pancreas, Liver:

   • Organs related to digestion and metabolism.

5. Respiratory Epithelium:

   • Tissues lining the respiratory tract.

Both Ectodermal and Endodermal Derivatives:

• Mouth, Teeth:
  • Components originating from both outer and inner embryonic layers.

Common Origin of Blood Vessels and Cells:

• Blood vessels and cells come from mesenchyme, an early formative tissue, with angioblast as the initial cells.

In Simple Terms:

• Different body organs and structures come from specific layers during embryonic development.
• Ectodermal derivatives involve things like the nervous system, senses, and skin.
• Mesodermal derivatives include bones, muscles, and organs of the immune and reproductive systems.
• Endodermal derivatives are related to digestive and respiratory organs.
• Some structures, like the mouth and teeth, have contributions from both outer and inner layers.
• Blood vessels and cells have a common origin in the mesenchyme, with angioblasts playing a crucial role.