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Cell death in exorbital lachrymal gland of anophthalmic mutant rat during postnatal development
Abstract:
Regression in the exorbital lachrymal gland was observed in congenital blind mutant rats lacking eyeballs and optic nerves. The morphological changes during postnatal development in acinar cells of the lachrymal gland of mutant rats were compared with those of normal rats at day 13 (before the opening of the eyes), day 30 (15 days after opening of the eyes) and the adult (90 days). Atrophy of the lachrymal gland is most likely to be associated with absence of functional signals. During regression, there is a massive elimination of cells from the acini; no fibrosis or immune reaction (lymphocytic infiltration) was observed in the gland. This atrophy in the lachrymal gland of blind rats was not associated with the biochemical markers of apoptosis. Present observations indicate that cell elimination from the lachrymal gland in blind rats is a special type of apoptosis, where cell homeostasis is not required.
Insights
Congenital blindness in rats leads to significant atrophy of the exorbital lachrymal gland. This regression involves massive cell elimination, a unique form of apoptosis not linked to typical biochemical markers.
Area of Science:
- Developmental biology
- Ophthalmology
- Cell biology
Background:
- The exorbital lachrymal gland plays a crucial role in tear production and ocular surface health.
- Functional signals, particularly visual input, are hypothesized to influence gland development and maintenance.
- Congenital blindness, characterized by the absence of eyeballs and optic nerves, presents a unique model to study sensory deprivation effects on gland development.
Purpose of the Study:
- To investigate the morphological changes and cellular processes in the exorbital lachrymal gland of congenital blind mutant rats during postnatal development.
- To compare the lachrymal gland development in blind rats with that of normal rats at key postnatal stages.
- To elucidate the mechanism of cell elimination during gland regression in the absence of visual input.
Main Methods:
- Morphological analysis of acinar cells in the exorbital lachrymal gland of congenital blind mutant rats and normal rats.
- Comparative study at three postnatal time points: day 13 (pre-eye opening), day 30 (post-eye opening), and day 90 (adult).
- Assessment for signs of fibrosis, immune reaction (lymphocytic infiltration), and biochemical markers of apoptosis.
Main Results:
- Congenital blind rats exhibited significant regression and atrophy of the exorbital lachrymal gland compared to normal rats.
- Massive cell elimination from acini was observed during regression, without evidence of fibrosis or lymphocytic infiltration.
- The observed atrophy was not associated with standard biochemical markers of apoptosis, suggesting an atypical cell elimination pathway.
Conclusions:
- Absence of functional signals, likely visual, is strongly associated with the atrophy of the exorbital lachrymal gland in blind rats.
- Cell elimination during lachrymal gland regression in blind rats represents a specialized form of apoptosis, distinct from pathways requiring cell homeostasis.
- These findings highlight the critical role of sensory input in the normal development and maintenance of exorbital lachrymal gland structure and function.