Ultrastructure investigation of the upper and lower eyelids ofElanus caeruleus
Transmission electron microscopical study of the eyelids skin ofElanus caeruleus revealed melanocytes of spherical to oval shape
and are located mainly in the basal layer of the epidermis. Moreover,
they have an oval nucleus with clumps of condensed chromatin. The
cytoplasm of the melanocytes has numerous melanin granules and the
cytoplasmic processes of melanocytes were also clearly observed (Fig.7a
&b).
The keratinocytes in stratum spinosum are characterized by a large
rounded euchromatic nucleus. They are tightly connected by numerous
tonofilaments (keratin filaments) crossing the intercellular spaces and
extending into junctions between the cells (Fig.7a &b).
The Langerhans cells are non-pigmented, and found in the basal and
spinosum layers. They are characterized by pale cytoplasm, deeply
indented and heterochromatic nucleus and the presence of specific
Langerhans granules. In addition, free ribosomes, mitochondria and some
membranous vesicles of variable size (Fig. 7a & c). The stratum corneum
constitutes the superficial layer, which lacks nuclei and is formed of
wavy keratin (fig .7a)
The ultrastructure of the conjunctival epithelium of the lower eyelid
revealed irregular cytoplasmic extensions emerging from the cell
surface. Moreover, the epithelial cell contains a round and euchromatic
nucleus and is enriched with smooth endoplasmic reticulum, few
mitochondria and numerous membranous vesicles of varying size (Fig. 7d).
.
Morphological
investigation of the nictitating membrane of Elanus caeruleus
The nictitating membrane of Elanus caeruleus is a white opaque
membrane, have palpebral and bulbar surfaces (Fig.8a). Anatomical and
scanning electron microscopy of
the nictitating membrane
revealed several folds on their
surfaces (Figs.8 a& c). the irregular surface of the free margin has a
few shallow pores (Fig.8b).
Furthermore, moderate-density cytoplasmic extension appeared in the
apical cells on the bulbar surface (Fig. 8), which disappears towards
the fornix conjunctiva bulbi and the intercellular border of the bulbar
surface (Fig.8e). Many pores scattered between the folds of the bulbar
surface (Fig.8e).
The laboratory observation of the movement of the eyelids ofElanus caeruleus showed that the nictitating membrane slips
rapidly in an oblique direction from the dorsonasal angle toward the
ventrotemporal direction (Fig.9).