Isolation of Intact Eyeball to Obtain Integral Ocular Surface Tissue for Histological Examination and Immunohistochemistry

Summary

This protocol describes a method for the isolation of the mouse eyeball with eyelid, ocular surface, anterior and posterior segments in relatively intact position.

Abstract

Ocular surface (OS) consists of an epithelial sheet with three connected parts: palpebral conjunctiva, bulbar conjunctiva and corneal epithelium. Disruption of OS would lead to keratitis, conjunctivitis or both (keratoconjunctivitis). In experimental animal models with certain genetic modifications or artificial operations, it is useful to examine all parts of the OS epithelial sheet to evaluate relative pathogenetic changes of each part in parallel. However, dissection of OS tissue as a whole without distortion or damage has been challenging, primarily due to the softness and thinness of the OS affixed to physically separate yet movable eyelids and eyeball. Additionally, the deep eye socket formed by the hard skull/orbital bones is fully occupied by the eyeball leaving limited space for operating dissections. As a result, direct dissection of the eyeball with associated OS tissues from the facial side would often lead to tissue damages, especially the palpebral and bulbar conjunctiva. In this protocol, we described a method to remove the skull and orbital bones sequentially from a bisected mouse head, leaving eyelids, ocular surface, lens and retina altogether in one piece. The integrity of the OS sheet was well preserved and could be examined by histology or immunostaining in a single section.

Introduction

The ocular surface consists of a continuous sheet of regionalized epithelium including palpebral conjunctiva, bulbar conjunctiva and cornea¹. Many glandular structures are associated with the ocular surface epithelium and together generate a layer of tear film protecting the cornea surface from drying and environmental invasions². Disruption of OS would lead to keratitis, conjunctivitis or both (keratoconjunctivitis). Both genetic factors and environmental irritants or their interactions contribute to pathological alterations of the OS^3,4. Accordingly, a variety ....

Protocol

All procedures involving the use of mice were approved by the Animal Care and Use Committee, Zhongshan Ophthalmic Center, and adhered to ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.

1. Dissection of eyeball with intact ocular surface and eyelids

1. Dissect the head.
   1. Euthanize postnatal day 10 (P10) and P28 mice (see the Table of Materials for mouse strains) by cervical dislocation, cut the head off the neck by a pair of sharp sc.......

Discussion

One critical reminder for preparation of the intact eyeball is that all orbital bones must be removed completely, especially the juga and lacrimal bones, which are small and located near the bottom of eye socket. Any left-over bones may complicate the ensuing histology. In case a tiny piece of bone was not completely removed from dissection by accident, it may be picked out from the embedding paraffin block using a pair of sharptweezers. The hole left behind should be filled with melted paraffin after this operation.

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Materials

Name	Company	Catalog Number	Comments
1× Phosphate buffered saline (PBS)	Transgen Biotech	FG701-01
50ml centrifuge tube	Corning	430829
Adhesive microscope slides	Various
Alexa Fluor 488 Phalloidin	Invitrogen/Life Technologies	A12379	Suggested concentration 1:500 - 1,000
Alexa Fluor 568 Phalloidin	Invitrogen/Life Technologies	A12380	Suggested concentration 1:500 - 1,000
Anti-K12 antibody	Abcam	ab124975	Suggested concentration 1:1,000
Anti-K14 antibody	Abcam	ab7800	Suggested concentration 1:800
Citric acid	Various
Cover slide	Various
Curved forceps	World Precision Instruments	14127
Dissecting microscope.	Olmpus	SZ61
Ethyl alcohol	Various
Fluorescent Microscope	Zeiss	AxioImager.Z2
Fluoromount-G Mounting media	SouthernBiotech	0100-01
Micro dissecting scissors-straight blade	World Precision Instruments	503242
Microwave ovens	Galanz	P70D20TL-D4
Mouse strains	C57/BL6 and Sv129 mixed
No.4 straight forceps	World Precision Instruments	501978-6
Normal Goat Serum	Various
Paraformaldehyde (PFA)	Various		Prepare a 4% solution in 1× PBS and filter with 0.45μm filter membrane
Tissue culture dish	Various
Trisodium citrate	Various
Triton X-100	Sigma-Aldrich	SLBW6818