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Macrophage invasion and phagocytic activity during lens regeneration from the iris epithelium in newts
1Department of Anatomy, School of Medicine, West Virginia University, Morgantown 26506.
Insights
Early lens regeneration in newts involves iris epithelial cells transforming into a new lens after lentectomy. Macrophages clear debris, facilitating this remarkable regenerative process.
Area of Science:
- Regenerative biology
- Developmental biology
- Ophthalmology
Background:
- Lens regeneration is a complex process observed in some amphibians.
- Understanding the cellular mechanisms of lens regeneration is crucial for potential therapeutic applications.
Purpose of the Study:
- To investigate the early cellular events during lens regeneration from the iris in adult newts.
- To characterize the role of macrophages and the morphological changes in iris epithelial cells post-lentectomy.
Main Methods:
- Light and electron microscopy were used to examine sectioned, plastic-embedded irises.
- Specimens were collected at regular intervals (0-15 days) after lens removal (lentectomy).
- Cellular features of macrophages and iris epithelial cells were analyzed.
Main Results:
- Macrophages infiltrated the iris epithelium, phagocytosing melanosomes and cell fragments.
- Iris epithelial cells near the pupil margin elongated, lost pigment, and developed abundant polyribosomes.
- Intercellular spaces within the iris epithelium enlarged, and depigmented cells formed a lens vesicle.
Conclusions:
- The study elucidates the initial cellular dynamics of lens regeneration in newts.
- Macrophage activity and dedifferentiation of iris epithelial cells are key early events in this regenerative process.
Abstract:
Following removal of the lens through the cornea, early stages of lens regeneration from the dorsal iris of the adult newt, Notophthalmus viridescens, were studied using light and electron microscopic observations on sectioned, plastic-embedded irises. Specimens were fixed in Karnovsky's fixative every 2 days from 0 to 12 and 15 days after lentectomy. Infiltration of the iris epithelium by macrophages and their phagocytosis of melanosomes and small fragments of iris epithelial cells were observed. These macrophages were characterized by coarse nuclear chromatin, numerous mitochondria, free ribosomes, granular endoplasmic reticulum, Golgi complexes, vesicles, lysosomes, and phagosomes containing ingested melanosomes. Lamellipodia of varying length projected from their surface. Most of the cells lying on or close to the posterior surface of the iris could be identified as macrophages by these criteria. During this period, there was enlargement of the intercellular spaces within the iris epithelium. The iris epithelial cells near the margin of the pupil elongated, lost their melanin pigment and some associated cytoplasm, and acquired abundant free polyribosomes to form a lens vesicle of depigmented cells.