Eye and Ear Slide Number 1.  Cross-section through the anterior surface of the lens.  The anterior 
layer of epithelial cells is marked by an arrow.  The remainder of the lens that can be seen in this 
picture is comprised of secondary lens fibers.

Slide Number 2.  Cross-section through the iris.  Recall that the iris is comprised of cells that are 
derived from both the neural retina and uveal (choroidal) layers of the eye.  Arrowhead marks 
pigmented epithelial cell layer located at the most posterior portion of the iris.  This surface of the iris 
is positioned adjacent to the lens.  The sphincter pupillae muscle is marked by the arrow.  The 
remainder of the iris is comprised of connective tissue.

Slide Number 3.  Cross-section through the limbic region of the tunica fibrosa.  Note change in 
density and clarity of endothelial cell layer between cornea (arrow head) and sclera (arrow).  
Longitudinal lines through cornea are an artifact of sectioning.

Slide Number 4.  Cross-section through the three layers of the eye.  Sclera, choroid and neural retina.  
Note extensive vascularization of choroid layer.  Recall that the layer of pigmented cells most closely 
associated with the photoreceptor outer segments, the retinal pigmented epithelial cells (arrow), is 
derived from the neural retinal layer, not from the choroid.  The white space between the choroid and 
sclera is an artifact of fixation.

Slide Number 5.  Cross-section through the ciliary body and lens of the eye.  Note the ciliary 
processes (CP) and ciliary muscle (CM).  As well as some of the zonule fibers (ZF) and the edge of 
the lens itself (L).  Recall that the ciliary process is comprised of cells from both the neural retinal 
and uveal (choroidal) layers.

Slide Number 6.  Cross-section through the cornea.  Recall that the cornea is comprised of 5 layers.  
Most superficial is a layer of epithelial cells that is 5 to 6 cells thick.  Following this layer is 
Bowman’s membrane, a cell free layer of random crossing collagen fibers.  Next is the stroma which 
constitutes 90% of the total thickness of the cornea.  It is comprised of parallel collagen fibers, 
fibroblasts and lymphoid cells.  Next is Descemet’s membrane, the basement membrane for the final 
layer, the endothelial cell layer.

Slide Number 7.  Cross-section through the neural retina.  The different layers of the retina are 
labeled.  OS: photoreceptor outer segments, IS: photoreceptor inner segments, EN: external nuclear 
layer, EP: external plexiform layer, IN: inner nuclear layer, IP: inner plexiform layer, GC: ganglion 
cell layer.  Finally the arrow labels the retinal pigmented epithelial cells (RPE).

Slide Number 8.  Cross-section through the organ of Corti in the mammalian cochlea.  Arrowhead 
marks inner hair cell.  Arrows mark three outer hair cells.  The overlying tectorial membrane (TM) is 
somewhat decreased in size as a result of fixation.  Recall that in a living organ of Corti the 
stereociliary bundles from the hair cells are embedded in the tectorial membrane.  Dendrites from 
neurons located in the spiral ganglion (SG) to make contact with hair cells.