Abstract
Purpose: :
During mouse corneal development the rate of proliferation, as measured by the labeling index, increases steadily in the first week of life and peaks at around P7-P10. The rate of proliferation then begins to decline rapidly prior to eye opening around P12. By P15 the proliferation is approaching the same level typically seen in adult corneal epithelium (Tseng et al, 1999). Therefore, Notch activation in the mouse cornea was evaluated during these periods by immunohistochemistry.
Methods: :
Adult C57BL/6 mice were mated and their pregnancies were timed. The newborn mice were collected on postnatal day (P) 10, P15, and P90. Frozen and paraffin sections of neonatal mouse corneas were prepared. Notch activity at each stage of development was determined by immunostaining for the Notch intracellular domain (NotchIC), the active form of Notch.
Results: :
During neonatal corneal development, NotchIC was detected in occassional basal cells at P10. By P15, NotchIC was detected in most of the basal cells and by P90 was detectable in all of the basal and early suprabasal cells of the corneal epithelium.
Conclusions: :
In the developing mouse corneal epithelium it appears that Notch activity is inversely correlated with the degree of proliferation. The inverse correlation between Notch signaling and the proliferative status of the cornneal epithelium is consistent with the idea that Notch functions in corneal epithelial differentiation.
Keywords: cornea: epithelium • proliferation • wound healing