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. Author manuscript; available in PMC: 2016 Oct 1.
Published in final edited form as: Exp Eye Res. 2015 May 26;139:1–12. doi: 10.1016/j.exer.2015.05.011

Figure 2. Rat Optic Nerve Head Macroscopic and Microscopic Relationships II.

Figure 2

Horizontal (panels - A, B, C and D) and vertical (panels - E, F, G and H) sagittal views of the rat ONH centered upon the scleral portion of the neurovascular canal (A and E). Panels (C) and (G) are digital horizontal and vertical sagittal sections (location relative to the ONH marked as C’ and G’ in (A) and (E) of the same histomorphometric reconstruction in which acquired transverse section images were shown in Figure 1. Panels D and H are the same sections showing the delineation of the different structures. The process of creating digital radial sagittal sections from the histomorphometric volume is explained in Figure 3, below. Panels (B) and (F) are histologic sections of another eye acquired in locations similar to (C) and (G). Note the continuity of the choroidal and perineural vascular plexus within both sections. Most published descriptions of the rat ONH show horizontal (C) or vertical (G) sagittal sections of the ONH that are cropped close to the end of the sclera which has the effect of emphasizing the similarities of the neurovascular canal to the scleral canal of the primate. However within the horizontal (C) and vertical (G) digital sagittal sections of the histomorphometric reconstructions, the importance of the vascular plexus that surrounds the nerve within the neurovascular canal, the sclera sling and the inferior arterial vessels can be appreciated. Note also the general temporal slant of the nerve in (B) and the superior slant of the nerve in (F). Taken together, these observations within horizontal and vertical sagittal sections confirm the general superior temporal path of the optic nerve tissues suggested within the serial transverse section images of Figure 1 (see Figure legend). Note that within panels (C) and (G) of Figure 2, the dark shadows extending upward from the sclera are a result of the fact that in serial transverse sectioning from the vitreous (top) to the orbital optic nerve (bottom) the dark choroidal pigment can be seen until the sectioning plane passes through it, creating the appearance of a shadow within the retina and vitreous . CRV- Central retinal vein, LPCA- Long Posterior Ciliary Arteries. CRA-Central Retinal Artery; N – Nasal; T – Temporal; I – Inferior; S – Superior.