الفهرس 
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Abstract
The aim of this work is clarifing the histological structure, the
histochemical and enzymatic activity, scanning electron microscopy and
ultrastructure of the camel cornea in different ages.
This work was carried out on the cornea of99 camel (66 male and
33 female) in different ages from right and left eyes from apparently healthy
camels which classified into three groups according to the age: young age
(1.5-3 years), middle age (5-8 years) and old age (over 8 years).
The camel cornea was consisted offour layers, this layers were; the
epithelium, the stroma (substantia propria), Descemet s membrane and the
endothelium. The corneal epithelium was stratified squamous nonkeratinized,
it represented about 24 % of the total corneal thickness. The
numbers of cell layers were 12 to 16 layers of epithelial cells. Its thickness
and number of layers increased with advancing the age. These layers
consisted of three types of cells: outer flattened squamous cells, middle
polyhedral cells and a single layer of basal columnar cells rested on
basement membrane. The basement membrane in the young age (1.5-3
years) was non wavy, in the middle age (5-8 years) was undulated in some
areas only but in the old age (over 8 years) was undulated along the course
of the cornea.
The epithelium of the camel cornea contained glycogen granules,
especially in the young age (1.5-3 years) in the superficial layers and
decreased with increasing the age. The nuclei of the epithelial cells
characterized by indentations especially in the basal columnar and middle
polyhedral cells. The cytoplasm of basal and polyhedral cells contained
many cytoplasmic organelles in the young and middle ages but in the old
age, it contained few organelles and many vesicles. The polyhedral cells
form numerous cytoplasmic processes interdigitated with each other and
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joined with numerous desmosomes. The basal cells attached with the
basement membrane through hemidesmosomes. the intercellular spaces
were increased in width toward the corneal surface.
With scanning electron microscopy the surface of the epithelium
carries numerous microvilli and microplicae. The microplicae increased in
the young ages but the microvilli increased in the adult ages.
The stroma of the cornea represented about 71 % of the total corneal
thickness and formed from parallel bundles of collagen fibrils which
increased in the intensity toward Descemet s membrane. Keratocytes were
the cellular element of the stroma which lie in between the collagen bundles
and appeared flattened and had long cytoplasmic processes parallel to the
collagen bundles. It had more active elongated nucleus and more
cytoplasmic organelles in the young and middle ages cornea. Its intensity
decreased with the age.
The stroma contained proteoglycans and glycoproteins. The proteoglycans
consists of sulfated acidic mucopolysaccharides bind with protein. The
amount of acidic mucopolysaccharides in the anterior stroma larger than that
of the posterior stroma.
Descernets membrane was very thick membrane, represented about
4.5 % of the total corneal thickness and its thickness increased with the
increasing the age and contained low amount of acidic mucopolysaccharides
and rich with glycoproteins. By electron microscopy appeared as parallel
laminae of amorphous material separated by narrow slits.
The endothelium was a single layer of flattened cells, it represented
about 0.5 % of the total corneal thickness. With SEM it appeared hexagonal
in shape and studded with short microvilli on its surface.
The limbus is the junction between the cornea and sclera and differ
from the cornea in the following:
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The limbal epithelium was lower in the numbers oflayers (9 to 12 layers),
decreased in its thickness and the limbal epithelium was pigmented
especially basal layer and rested on a wavy basement membrane. The
connective tissue of the limbus was more loosely and irregularly in the
anterior limbus and increased in the intensity of the collagen fibrils toward
Descernet’ s membrane. Also the connective tissue of the limbus was rich in
blood vessels and lymphatic channels and contained different type of cells
(fibroblasts, melanocytes, lymphocytes, mast cells, macrophages and plasma
cells). In between the collagen bundles some elastic fibers were present and
nerve fibers were present under the epithelium.
The acid phosphatase enzyme gave a reaction especially in the
corneal epithelium, this reaction increased in the superficial layers of young
ages camel and decreased with increasing the age but in the stroma and
Descemet s membrane gave a weak reactions. ”
The alkaline phosphatase enzyme gave a slight reaction in middle
and superficial layers of the epithelium in all ages. It gave moderate reaction
in the basal layer of the epithelium in the young age and decreased with the
increasing the age. The stroma gave moderate reaction in the young age and
decreased with advanced age.
The succinic dehydrogenase enzyme showed a moderate reaction in
the basal cells of the epithelium in all ages but gave a slight reaction in the
middle and superficial layers in all ages but the stroma and Descernet’ s
membrane gave a weak reaction.
The ATPase showed strong reaction in the epithelium of the young
ages especially in the superficial layers and the reaction decreased toward
the basement membrane and also decreased with the increasing the age. But
stroma and Descemet’ s membrane gave slight reaction in all ages. The
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endothelium gave a moderate reaction in the young ages and decreased with
the age.
The acetylcholinestrase gave a positive reaction 10 the anterior
stroma and basal epithelium in all ages.
The lipid presents in the epithelium in low amount in the young age
and increased with the increasing the age.