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Surface differentiation of the human corneal epithelium during prenatal development
1Alfried Krupp Labor, Universitäts-Augenklinik, Bonn, Federal Republic of Germany.
Insights
Human corneal development involves surface changes from early gestation. Microvilli and microplicae emerge around week 7, with adult-like features by week 22, indicating significant epithelial differentiation.
Area of Science:
- Developmental biology
- Ophthalmology
- Cell biology
Background:
- The anterior corneal surface undergoes significant morphological changes during embryonic and fetal development.
- Understanding these changes is crucial for comprehending normal eye development and potential congenital abnormalities.
Purpose of the Study:
- To investigate the differentiation process of the anterior corneal epithelium surface in human embryos and fetuses.
- To establish a timeline for the development of surface structures like microvilli and microplicae.
Main Methods:
- Scanning electron microscopy (SEM) was utilized to examine the surface morphology.
- Transmission electron microscopy (TEM) provided ultrastructural details of the developing corneal epithelium.
- Human embryonic and fetal samples were analyzed across a gestational range of 6.4 to 22 weeks.
Main Results:
- Microvilli and microplicae were infrequent before week 6/7 of gestation.
- These surface projections increased significantly in number starting around week 7.
- By week 22, the corneal surface morphology closely resembled that of an adult.
- Axially oriented microfilaments within microvilli (antennulae microvillares) were observed from week 16/17 onwards.
Conclusions:
- The anterior corneal epithelium exhibits distinct developmental stages characterized by the emergence and maturation of surface structures.
- The development of microvilli and microplicae follows a specific temporal pattern during human fetal development.
- The morphological maturation of the corneal surface by week 22 suggests functional readiness.
Abstract:
Using scanning and transmission electron microscopy, differentiation of the anterior surface of the corneal epithelium was studied in human embryos and fetuses with a gestation age from 6.4 to 22 weeks. Up to week 6/7 microvilli/microplicae are not often found; they arise in larger amounts beginning in week 7. During week 22, the morphological appearance of the corneal surface is almost adultlike. Antennulae microvillares and microfilaments running axially in microvilli can be found beginning with week 16/17.