Write a Note on fate of three germinal layers.
Write a Note on fate of three germinal layers.
Answer :
The vertebrate embryo begins as a uniform region of pluripotent cells, which soon transforms through a process called gastrulation into a more complex structure with three layers of differentiated cell types. These three germ layers are called endoderm (inner layer), mesoderm (middle layer) and ectoderm (outer layer) and will give rise to all cells and tissues of the adult organism.
- Endoderm (inner layer) → digestive and respiratory system
- Mesoderm (middle layer) → muscles, bones and dermis
- Ectoderm (outer layer) → epidermis, hair, nails, eyes and nervous system
Fate of Three Germinal Layers:
During gastrulation three primary germinal layers are formed. From these layers formation of tissues and organ takes place called as histogenesis, whatever the structures are developed from germ layers called as fate of germ layers.
Fate of Ectoderm:
Nervous system, pituitary adrenal medulla, proctodaeum, stomodaum, nasal cavity, enamel of teeth, external and internal ear, retina, lens, cornea, conjunctiva, Sweat glands, nails, hairs,epidermis of skin pineal gland etc.
Fate of Mesoderm:
Dentine of teeth, middle ear, lymphatic vessels, blood and blood vessel, heart, adrenal cortex, dermis of skin, muscles, connective tissue, bones, cartilage, kidneys, testis, ovaries, bone marrow, urinary and genital ducts, spleen etc.
Fate of Endoderm: Middle ear, epithelium of mid gut (pharynx to colon), glands of stomach and intestine, liver, pancreas, anterior pituitary, thyroid gland, parathyroid glands, thymus gland, eustachian tube, epithelium of urethra incuding associated glands, tongue, tonsils, lungs, larynx, trachea, bronchi, urinary bladder, vagina, vestibule, etc.