Template:Frog Cornea Timeline table

From Embryology
Frog Cornea Timeline
Stage Event
stage 25 cornea starts from a simple embryonic epidermis overlying developing optic vesicle
stage 30 detachment of lens placode, cranial neural crest cells start to invade the space between the lens and the embryonic epidermis to construct the corneal endothelium.
stage 41 second wave of migratory cells containing presumptive keratocytes invades the matrix, leading to formation of inner cornea and outer cornea. A unique cell mass (stroma attracting center) connects the two layers like the center pole of a tent.
stage 48 secondary stromal keratocytes individually migrate to the center and form the stroma layer.
stage 60 stroma space is filled by collagen lamellae and keratocytes, and the stroma attracting center disappears. At early metamorphosis, embryonic epithelium gradually changes to adult corneal epithelium, covered by microvilli.
stage 62 embryonic epithelium thickens and cell death is observed in the epithelium, coinciding with eyelid opening.
After metamorphosis cornea has attained the adult structure of three cellular layers, epithelium, stroma, and endothelium, and between the cellular layers lie two acellular layers (Bowman's layer and Descemet's membrane)
Table data from Xenopus laevis[1] | frog | vision
  1. Hu W, Haamedi N, Lee J, Kinoshita T & Ohnuma S. (2013). The structure and development of Xenopus laevis cornea. Exp. Eye Res. , 116, 109-28. PMID: 23896054 DOI.