ORGANOGENESIS-EYE EMBRYOLOGY

Organogenesis is an organ formation which is prepared by the embryo having three layered structure with separation of following layers.

ECTODERM

MESODERM

ENDODERM

Organ is formed by different groups of cells which interacts among themselves, and may consist of several component made up of different tissues after derived from different germinal layers.

Eye is an extremely complex organ, the cells that make up the various parts of the eye are contributed by

ECTODERM

MESODERM

 

• The retina, lens, are made up of ectodermal
• The cornea, iris, ciliary body are formed from cellular contributions of both ectoderm and mesoderm.
• The extrinsic and intrinsic muscles are purely mesodermal and so are the choroid and sclera
• The eyelid, lacrimal gland are ectodermal

 

Development of eyeball can be considered to commence around 22 of pregnancy when the embryo has 8-pairs of somites and is around 2mm in length.

 

STAGE OF GROWTH AND DEVELOPMENT-EMBRYONIC AND FETAL PERIOD

Embryo size – 2.6mm (3^rd week) – development of optics pit on either side of cephalic end of forebrain

Embryo size – 3.5mm (4^th week) – primary optic vesicle invaginates

Embry size – 5.5-6mm – development of embryonic fissure

Embryo size – 10mm (6^th week) – retinal layers, lens vesicle formed

Embryo size – 20mm (9week) – sclera, cornea, EOM differentiated

Embryo size – 25mm (10week) – lumen of optic nerve obliterated

Embryo size – 50mm (3^rd month) – optic tracts completed

Embryo size – 60mm (4^th month) – hyaloid vessels develop

Embryo size – 230-265mm (8^th month) – foetal nucleus of lens is completed.

Embryo size – 265-300mm (9^th month) – except macula, retina is fully developed

 

 

 

 

 

 

 

 

 

 

 

 PRIDHI PANWAR

  ASSISTANT PROFESSOR

  UCBMSH DEHRADUN

  OPTOMETRY DEPARTMENT