development of the angle of the anterior chamber

1. EMBRYOLOGYOFANGLEOFANTERIORCHAMBER
PRESENTER : DR.MAHENDAR

2. BENNINGHOFF SCHEMATIC
REPRESENTATION OF ANGLE.

3. 1. Retina-optic nerve;
• 2. Accommodation apparatus (lens, zonule, ciliary body with
ciliary muscle and choroid);
• 3. Diaphragm-iris;
• 4. Motility apparatus (sclera and extrinsic muscles);
• 5. Eyelids, lacrimal system, conjunctiva, and cornea.

4. ANATOMY OF ANTERIOR CHAMBER

5. • The sclera (yellow) extends into three prongs in its anterior end.
• the anterior one : the limbus.
• the middle one : the scleral septum.
• the posterior one is smaller : the spur.
• These three prongs form two channels: the anterior chamber lodges the
optical element – the cornea – and the posterior chamber houses the
filtration element – the Schlemm canal and the trabecular meshwork

6. THEROIES
Proposed theories of angle development are :
1. cleavage and separation
2. Atrophy and Resorption

7. CHRONODYNAMICS OF NORMAL ANTERIOR
CHAMBER ANGLE DEVELOPEMENT
• The anterior (cranial) part of the neural tube constitutes the
prosencephalon, which gives the lateral evagination forms the
primitive optic groove on its sides and then the optic vesicle.
• On day 26, the optic vesicle approaches the embryonic
ectoderm.
• On day 27, the crystalline plaque can be distinguished in this
ectoderm.

10. 2ND MONTH
• Day 33 - crystalline vesicle separated from ectoderm .
• Day 40 - the mesoderm surrounding the optic cup grows in between
the two so that there is a homogeneous mass of mesoderm
between the lens and the surface epithelium.
• Day 50 - incipient anterior chamber.
• Angle of anterior chamber occupied by the mesenchymal cells of
neural crest origin.

12. 3RD MONTH
• Ciliary body begins to appear.
• Iris development begins.
• The ciliary processes develop at the end of the 3rd month of
gestation.
• Abundant endothelized angle mesoderm.
• The primordium of the chamber angle appears between the 3rd and
5th month of gestation.

13. RETICULAR SYSTEM

14. TYPES OF MESODERMAL REMNANTS
• This triangle is bounded to the front by an external longitudinal
system of fibers making up the tendon of the Brücke muscle and
extending from the Schwalbe line to the longitudinal muscle.
• Remnants of the external longitudinal system will give rise to
trabecular formations attached to the external wall of the chamber
angle, which are later lined with the Henle layer and with pigment.

15. • Toward the back, it is bounded by the internal longitudinal
system .
• This system gives rise to the iris root, especially to the
avascular part (radiated cords).
• it extends from the iris base up to the radiated fibers of the
ciliary muscle (Ivanoff muscle) and it is the source of the future
iris root.

17. 4TH MONTH
• Ciliary processes fully formed.
• Schlemm‘s canal appears in the second half of the 4th month
which is developed from the small plexus of venous canaliculi
of endodermal origin.
• Uveal trabecular and corneoscleral differentiated (cellular).
• Abundant endothelized angle mesoderm

19. 5TH MONTH
• The anterior chamber appears in the middle of the 5th month.
• Schlemm‘s canal (endothelial vacuolization).
• Mesodermal resorption begins .
• The core of the trabeculae starts to form (cellular-fibrillary) .
• Iris fully developed.

20. 6TH MONTH
• At the beginning of the 6th month, the lens touches the
posterior surface of the cornea only at its posterior pole.
• The iridopupillary membrane, the central part of which later
gives rise to the pupillary membrane, and its peripheral part to
the iris stroma, is located in front of the lens capsule.
• In the middle of the 6th month anterior chamber development
finishes.

21. • Formation of aqueous humor.
• Mesodermal resorption continues.
• Posterior displacement of ciliary muscle starts.
• Formation of dilator pupillae begins.
• Sphincter muscle is fully differentiated.

22. 7TH MONTH
• the anterior chamber just reaches the Schwalbe line.
• Behind it, the mesodermal tissue has a very tight mesh; it extends
over the whole area from the scleral trabecular meshwork to the
radiated muscle and the ciliary process.
• Fenestration of the pretrabecular endothelial (Barkan) membrane.
• Posterior displacement of ciliary muscle.
• Circular part of ciliary muscle starts to develop from the radial muscle.

25. 8TH MONTH
• The anterior chamber enlarges in a distal direction.
• The meshes of the mesodermal tissue are looser .
• Disappearance of endothelial membrane.
• Displacement of ciliary muscle.
• Resorption of mesoderm are completed.
• Angle of anterior chamber is formed completely.

27. 9TH MONTH
• The anterior chamber enlarges even further.
• Limit of the anterior chamber past the scleral spur.
• The mesodermal tissue is reduced to a thin layer that will
later become the Busacca trabecular conjunctival layer, also
known as the Rohen iridoscleral membrane.
• Pupillary membrane disappear completely.
• Trabecular meshwork is less pigmented.
• Radial part attached to the longitudinal part of the ciliary
muscle.

29. AT 5 YEARS
• Dilator pupillae reaches the adult proportions by 5 years of
age.
• Iris stromal pigment develops after the birth.
• Angle recess formation is completed.

30. CHRONODYNAMICS OF NORMAL ANTERIOR
SEGMENT DEVELOPMENT