The sclerotic plates of the White Leghorn chicken

Chondrocranium and skeletal development of Phrynops hilarii (Pleurodira: Chelidae)

“…They are a plesiomorphy of several extant sauropsid groups (Franz-Odendaal 2006). Despite their general presence in turtles, mention of their development was usually omitted in the accounts of skeletal development of turtles (Andrews 1996;Franz-Odendaal 2006), in contrast with the detailed studies available for birds (Nelson 1942;Hall 1981). Andrews (1996) studied several cryptodirans and concluded that the scleral ossicles of this group develop by endochondral ossification.…”

Collagen organization in the chicken cornea and structural alterations in the retinopathy, globe enlarged (rge) phenotype—An X-ray diffraction study

“…2). This may be attributed to X-ray absorption and non-collagenous scatter from the scleral ossicles, a ring of bony plates which circumscribes the avian eye (Nelson, 1942;Murphy et al, 1995). Nevertheless, more peripherally, extensive areas of radial collagen can be clearly observed (Fig.…”

Intramembranous ossification of scleral ossicles in Chelydra serpentina

“…Their development has, however, only been studied in birds. In this taxon, the scleral ossicles are induced by transient scleral papillae, outgrowths of the conjunctival epithelium, and undergo an intramembranous mode of ossification (Curtis and Miller, 1938;Nelson, 1942;Murray, 1943;Coulombre et al, 1962;Coulombre, 1965;Hall, 1981, 1983;Hall, 1981;Pinto and Hall, 1991). There are 13-14 scleral ossicles in each eye of the domestic chicken (Gallus gallus).…”