Histological investigation of the eyelids of Egyptian agama
Histological investigation of the upper and lower eyelids of T .mutabilis revealed that the histological structure of both
eyelids’ external and internal surfaces is similar (Figs. 3 and 4)\RL.
The histological structure of the upper and lower eyelids and the
superior extension of T . mutabilis revealed that the
superior extension and the external surface of the upper eyelid are
composed of keratinized stratified squamous epithelium with 2-4
nucleated cell layers, covered with a hard keratin layer forming the
horny epidermal scales. The horny scales are connected by hinge regions
(Figs. 3 and 4). The internal surface of the upper eyelid is composed of
stratified cuboidal epithelium with 2-5 nucleated cell layers with oval
and rounded nuclei. The superficial cells have small protrusions (Figs.
4C1 and C2)\RL.
The dermal layer (stroma) located between the external and internal
surfaces is formed of fibrous connective tissue filled with densely
packed collagen fibers of varying orientations, blood vessels, muscle
fibers, and two types of pigment cells: iridophores and melanophores.
Iridophores contain brownish-yellow granules and are located beneath the
basement membrane of the keratinized stratified squamous epithelium.
Melanophores appear as black cells with dendrite-like extensions
scattered within the dermis (Figs. 3 and 4)\RL.
Histological investigation of the nictitating membrane of T .mutabilis revealed that it has two surfaces: an external surface
(upper surface) and an internal surface (basal surface) (Fig. 5). The
external surface of the nictitating membrane is composed of stratified
squamous epithelium. In contrast, the internal surface comprises one or
two nucleated cell layers with rounded nuclei connected to the
conjunctival epithelium. The connective tissue stroma of the nictitating
membrane is mainly made up of collagen fibers running in transverse
directions and containing blood vessels (Fig. 5d). The conjunctival
epithelium consists of one to three nucleated layers, and the connective
tissue comprises collagen fibers, blood vessels, and hyaline cartilage
(Fig. 5e).