Korean J Ophthalmol.  2005 Sep;19(3):213-218. 10.3341/kjo.2005.19.3.213.

Morphological Characteristics and Intercellular Connections of Corneal Keratocytes

• Kang GM
• Ko MK

• KMID: 754427
• DOI: http://doi.org/10.3341/kjo.2005.19.3.213

Abstract

PURPOSE
To investigate the morphological characteristics of keratocytes and the interconnection of keratocytes with adjacent keratocytes using the flat preparation method and scanning electron microscopy with a frontal section of the human corneal stroma. METHODS: The thin, corneal collagen lamellae were carefully dissected from the cornea (n=7), which had been stained by the flat preparation method. The remaining tissue was fixed in 3% glutaraldehyde and observed by transmission electron microscopy following the frontal section. RESULTS: The flat preparation revealed the corneal fibroblasts between the lamellae of the collagen fibers and showed that the ramifying cellular processes of the keratocytes were in contact with the cytoplasmic processes or cell bodies of neighboring fibroblasts. Two types of discrete subpopulations of keratocytes were identified: a smaller, cellular type of keratocyte with spindle-shaped nucleus with heterochromatin, and a larger, cellular type with a large indented nucleus with relatively scanty cytoplasm. Collagen fibers ran parallel to each other toward the fenestration of the cytoplasmic wall of the keratocyte. CONCLUSIONS: These flat preparation method results showed that the keratocytes within the corneal stroma are interconnected with the adjacent keratocytes, which indicates the presence of a functional communicating network through the keratocyte circuits within the stroma. A smaller, cellular type of keratocyte with spindle-shaped nucleus was morphologically differentiated from a larger, cellular type with a large, indented nucleus by flat preparation and transmission electron microscopy.

Keyword

Collagen; Electron microscopy; Flat preparation; Intercellular space; Keratocyte

MeSH Terms

Middle Aged
Microscopy, Electron, Transmission
Microscopy, Electron, Scanning
Intercellular Junctions/*ultrastructure
Infant
Humans
Corneal Stroma/*cytology/pathology
Child, Preschool
Child
Cell Size
Aged
Adult
Adolescent

Figure

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  Fig. 1. Multi-directional arrangement of the keratocytes is shown in the flat preparation of the thick—layered, lamellar flap. H—E stain X100.

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  Fig. 2. (A) Star—shaped Cytoplasmic processes are evident in the keratocytes 0f thin—Iayered7 lamellar flap. (B) The nuclei occupy most of the central part of the keratocyte with spindle-shaped cytoplasmic processes. Long, slender cytoplasmic processes are also shown. Flat preparation, H-E stain X400.

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  Fig. 3. (A) One-directionally arranged keratocyte showing the typical, long, slender cytoplasmic processes. (B) Two patterns of keratocytes staining are observed: small cell with strong staining (arrowhead) and large cell with weak staining (arrow). Flat preparation, H—E stain X400.

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  Fig. 4. (A) Syncytial arrangement of the keratocytes showing the thin, slender cytoplasmic processes connected by cellular junctions on one lamellar plane of collagen fibers in the frontal section. (B) Cytoplasmic processes formed by several keratocytes showing a star—shaped arrangement. Bar, 1 pm.

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  Fig. 5. (A) The indented nucleus occupying the major part of the cell. The cytoplasm surrounds the nucleus and has numerous microorganelles such as many stacks of rough endoplasmic reticulum and Golgi bodies with vesicles. Bar, 0.1 pm. (B) Two discrete subpopulations of keratocytes are connected by intercellular junction. The small, cellular type of keratocyte has a spindle—shaped nucleus with heterochromatin and the large, cellular type of keratocyte has a large, indented nucleus with relatively scanty cytoplasm. Bar, 1 pm.

• 

  Fig. 6. (A) Small cellular type of keratocyte has a prominent nucleoli with peripheral heterochromatin in addition to numerous microorganelles Within the cytoplasm. (B) Three or more keratocytes are connected by intercellular junction. The cells have many stacks of rough endoplasmic reticulum, and Golgi bodies with vesicles within the cytoplasm. Bar7 0.1 pm.

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  Fig. 7. The ketatocyte has multiple fenestrations on the Cyto—plasmic wall. The collagen fibers tun toward the fenestrations of the cytoplasmic wall of the keratocyte. Bar, 0.1 pm.

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  Fig. 8. (A) Many keratocytes are alternated with collagen fibers in this oblique section. Bar7 1 pm. (B) (C) Higher magnification of Fig 8A. Collagen fibers run parallel to each other toward the fenestration of the Cytoplasmic wall of the keratocyte. Bar, 0.1 pm.

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