الفهرس 
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Abstract
Investigation of the Harderian gland of the one-
humped camel during the prenatal life revealed :
1. The primordium of the Harderian gland was first observed in foetuses as early as 60 mm CUR length. This primordium was represented by a cellular prol-iferation of the conjunctival bulbar epithelium at the angle between the primordium of the nictit-ating membrane and the primordium of the fibrous coat of the eye.
2 At 150 mm CUR length the primordium of the Harder-
ian gland was represented by four canalized tubular structures constituting the anlage of the duct system of this gland.
3.The primary elements of the glandular end-pieces were demonstrated in camel foetuses of 520 mm length as various cellular proliferations from the duct anlages.
4.The rate of proliferation of the end pieces was greatly enhanced at the periphery of the glandular lobules in foetuses of 1030 mm CVR length and reached
its maximal potency when the foetuses reached a length
of 1150 mm.
The qualitative differention of the glandular end-pieces was first demon strated in foetuses of 1150 mm CUR length. 6.In full-term foetuses , the glandular cells were differentiated into two types viz., dark and light cells.
7.The volume percentage of the parenchyma was relatively higher in male than in female camel foetuses. The rate of growth of the parenchyma was relatively faster in male than in female foetuses.
8.Small cartilagenous plates were presented within the peritubular connective tissue in camel foetuses of 150 mm CUR length.
9.The volume percentage of the cartilagenous plates increased gradually till it reached its maximum in foetuses of 720-1020 mm CUR length then decreased gradually towards the end of gestation where it reached its minimum in full-term foetuses.
10.1n foetuses of 320 mm Ck/R length some lymphocytes started to appear accumulating around some capillaries within the connective tissue below the bulbar conjun-ctival epithelium.
11.The lymphatic tissue increased towards the end of pregnancy where it was about three folds as large as that detected in 980 mm CUR length foetuses. 12.The connective tissue cells began to differentiate into some lipoblasts scattering inbetween the glandular end-pieces in foetuses of 450 mm CUR length.
13.The volume percentage of the adipose tissue demonstrated a gradual increment in both sexes towards the end of gestation and reached its maximal amount in full-term foetuses.
14.The primordium of the nictitating glands originated as pigmented epithelial cord-like proliferation of the conjunctival epithelium at the angle between the nictitating membrane and the palpebral conjunctival surface of 320 mm CUR-long camel foetuses .
15.At the end of gestation, the nictitating gland was represented by a single lobe which opened by a single excretory duct at the angle between the palpebral surface of the nict itat’ing membrane and the hairy palpebral conjunctival surface.
16.Histochemically, the foetal Harderian gland of one-humped camels started to demonstrate PAS- positive granules within their duct anlage at 430 mm CUR length. These granules increase towards the end of gestation. However, the glandular cells of the end-pieces began to demonstrate moderate PAS-positive cytoplasmic granules in foetuses of 520 mm CUR length. 17. The cells of both the glandular end-pieces as well as the ducts demonstrated various sudanophilic materials within their cytoplasm.
Investigation of the Harderian gland of the one-humped camel, during the postnatal life revealed:
1.They are compound tubulo-alveolar glands. The gland-ular end-pieces were of three types: the first type (78%) was exclusively lined by light cells. The second type (15%) was lined by both light and dark cells. However, the third type(7%) was lined exclusively by dark cells.
2.Myoepithelial cells were demonstrated between the glandular cells and the basement membrane.
3.The intralobular ducts demonstrated some oval or goblet-like mucus-secreting cells and few pigment cells.
4.The interlolular ducts presentd aciodophilic granules within their cells. The lining epithelium of these ducts contained large cylindrical or dome-shaped mucus-
secreting cells.
5.The main ducts were represented by four ducts which opened on the bulbar conjunctival epithelium. The wall of these ducts presented several large mucus-secreting cells and pigment cells. 6. The interstitial tissue presented fibroblasts and numerous plasma cells. The amount of the plasma cells increased in old specimens.
7- Lymphoid tissue demonstrated itself in diffuse
or organized manner between the end-pieces ,below
the bulbar conjunctival surface and around the intra - or interlobular ducts.
8.The volume percentage of the lymphoid tissue decreased by the advancement of age.
9.The Harderian gland was traversed by several
cartilagenous platelets which percentage decreased in old specimens.
10.Several pigment cells were demonstrated within the interlobular connective tissue interlobular ducts, main ducts and the bulbar conjunctival epithelium.
11.Several adipocytes were found either sporadically
or in various aggregations inbetween the end-pieces.
12. The cells of the different ducts showed FAS-positive granules which reaction intensity was more than
that observed within the glandular cells. 13.The glandular end-pieces showed abundant acid-mucopolysaccharides at the apical portion of their cells.
14.The glandular cells and the cell of the ducts dem-onstrated various amounts of cytoplasmic basophelia.
15.Various sudanophilic materials were demonstrated within the cells of the ducts and the glandular end-pieces.
IN CONCLUSION:
The present investigation indicated the diversity of origin of both the Harderian .and nictitating glands not only regarding the site but also upon development bases.
The role of the Harderian gland in protecting the eye ball is not only resticted to its unique secretory materials which lubricate and disinfect the conjunctiva, but also to its lymphocytic device which implysa sig-nificant immunological role and indicates a•iirect participation of this gland in the immune response.
The Harderian gland of the one-humped camel showed sex differences not only during the pre-but also during the postnatal life. This differences might be attributed to sex hormones.