Study on cornea histogenesis in sheep embryo

Abstract

In this study, 36 samples of sheep fetal at different and modal ages have been used. Sample after preparation and determination of age immediately fixed and anatomic and histological studies were done. In Histological studies in addition to conventional H&E staining, two staining that include Masson trichrome and verhuff staining was used. The yield results revealed that cornea is distinct in the second month of embryonic period and in the next ages spends the stages of growth. From the beginning in cornea formed in horizontal ellipse type so the internal curve of is larger than external curve. The growth process from the point of longitudinal diameter, transverse diameter and corneas height from the border of sclera is ascending with the raising of age. Upper and lower eyelids was impacted in the early and late time of the second month and separated from together again in the third month of embryonic period. Third eyelid approximately appears in 120 days of age in the internal angle of the eye. Histology of external epithelial tissue growth observed from simple cubic to six layers stratified cubic form. Matrix has been strengthened from point of cells (fibroblast) and a filaments (collagen) with the rising of age. Increases in the elastic filaments are appreciable at the end of embryonic stages. Desmit membrane appears as limiting membrane in the early time of the second month of embryonic period in the beneath of internal epithelial tissue and also growth with rising of age. Desmit membrane has any elastic filaments. No Bowman layer or the external limiting membrane was seen in this animal. Tricrummasson staining confirms collagen filaments and verhuff staining confirm elastic filaments growth with rising of age.

Keywords

• sheep
• Eye
• Cornea
• Histogenesis