Anterior segment growth and peripheral neural pathways in chick.
OBJECTIVE
To learn if peripheral nerve pathways are necessary for corneal expansion and anterior segment growth under a 12-hr light:dark cycle or for the inhibition of corneal expansion under constant light rearing.


METHODS
Recently hatched White Leghorn chicks under anesthesia received unilateral ciliary ganglionectomy (CGx), cranial cervical ganglionectomy (Sx), or section of the ophthalmic nerve (TGx), along with sham-operated and/or never-operated control cohorts. Chicks were reared postoperatively under either a 12-hr light:dark cycle or under constant light. After 2 weeks and with the chicks under anesthesia, corneal radii of curvature and diameters were obtained with a photokeratoscope, refractometry and A-scan ultrasonography were performed, and the axial and equatorial dimensions of enucleated eyes were measured with digital calipers. Corneal areas were calculated from corneal curvatures and diameters.


RESULTS
Despite the rich peripheral innervation to the eye, the selective denervations performed here exerted remarkably limited effects on corneal expansion and anterior segment development in chicks reared under either lighting condition. Ophthalmic nerve section did reverse in large part the inhibition of equatorial expansion of the vitreous chamber occurring under constant light rearing.


CONCLUSIONS
The ciliary, sympathetic, or ophthalmic peripheral nerve pathways to the eye are not required either for corneal expansion and anterior segment development under a 12-hr light:dark cycle or for the inhibition of corneal expansion under constant light rearing. The ocular sensory innervation may be a means for regulating vitreous cavity shape.
Stone
Richard A
RA
Department of Ophthalmology, University of Pennsylvania, School of Medicine, Scheie Eye Institute, Philadelphia, Pennsylvania 19104-6075, USA. stone@mail.med.upenn.edu
Sugimoto
Reiko
R
Capehart
Cheryl
C
Pendrak
Klara
K
Lin
Ton
T
D000818:Animals; D000831:Animals, Newborn; D000869:Anterior Eye Segment / Q000254:growth & development* / Q000294:innervation*; D002645:Chickens; D002924:Ciliary Body / Q000294:innervation; D003315:Cornea / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000294:innervation; D003623:Dark Adaptation; D015171:Ganglionectomy; D009334:Neck Muscles / Q000294:innervation; D009434:Neural Pathways / Q000502:physiology; D009882:Ophthalmic Nerve / Q000502:physiology / Q000601:surgery; D010525:Peripheral Nerves / Q000502:physiology*; D012668:Trigeminal Ganglion / Q000502:physiology / Q000601:surgery; D014463:Ultrasonography