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Apoptosis and lens vesicle development
1Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto, Nagasaki, Japan.
Purpose:
To study the development of the rat lens vesicle in relation to apoptosis.
Materials And Methods:
Fetuses of Wistar Kyoto rats were removed by laparotomy on day 10-15 of gestation. Some fetuses were fixed in 2% paraformaldehyde and embedded in paraffin for a TUNEL technique examination of DNA fragmentation. Macrophages were stained immunohistochemically with antibody. Some fetuses were fixed in 4% glutaraldehyde and 1% osmic acid and embedded in Luveak 812, then examined with a transmission electron microscope (TEM).
Results:
On day 11 of gestation (E11) before the start of lens invagination, apoptotic changes were noted in the cells between the surface ectoderm and optic vesicle, with the appearance of phagocytic cells. Apoptotic cells were present at the junction of the surface ectoderm and the lens placode, in the ventral and dorsal thirds of the lens placode and in the outer layer of the optic vesicle in the same axes on E12. Apoptotic changes appeared in the lens stalk, surface ectoderm and the anterior lens epithelium on E12.5. The lens vesicle was detached completely from the surface ectoderm by E13 and some cells had the typical characteristics of macrophages in the extracellular space between the surface ectoderm and the anterior lens epithelium. Apoptotic changes were confirmed by the TUNEL method, and macrophages were stained immunohistochemically.
Conclusions:
Apoptosis may have a major role during the whole process of lens vesicle development. Apoptosis may eliminate the cells between the surface ectoderm and the optic vesicle, help trigger invagination and facilitate separation from the ectoderm. Apoptosis might aid in the bowing of the optic vesicle during lens invagination.
Insights
Apoptosis plays a key role in rat lens vesicle development, eliminating cells to facilitate invagination and separation from the ectoderm. This programmed cell death is crucial for proper lens formation.
Area of Science:
- Developmental Biology
- Cell Biology
- Ophthalmology
Background:
- Lens vesicle development is a complex process involving precise cellular events.
- Apoptosis, or programmed cell death, is a fundamental biological mechanism.
- Understanding cell fate during embryonic development is crucial for developmental biology.
Purpose of the Study:
- To investigate the role of apoptosis in the development of the rat lens vesicle.
- To correlate apoptotic changes with specific developmental stages of the lens vesicle.
Main Methods:
- Utilized Wistar Kyoto rat fetuses from day 10-15 of gestation.
- Employed TUNEL technique for DNA fragmentation analysis (apoptosis detection).
- Used immunohistochemistry for macrophage staining and transmission electron microscopy (TEM) for ultrastructural examination.
Main Results:
- Apoptotic changes and phagocytic cells were observed as early as day 11 of gestation, prior to lens invagination.
- Apoptotic cells were identified at critical junctions, including the surface ectoderm, lens placode, and optic vesicle.
- Macrophages were present in the extracellular space, aiding in the clearance of apoptotic cells during lens vesicle separation.
Conclusions:
- Apoptosis is integral to lens vesicle development, from initial invagination to final separation.
- Programmed cell death aids in eliminating cells between the ectoderm and optic vesicle, promoting invagination.
- Apoptosis likely contributes to the morphogenetic shaping of the optic vesicle during lens formation.