The optic nerve of the cat: appearance and loss of axons during normal development.
The number of axons in the optic nerve has been estimated in cats ranging in age from mid-gestation to adulthood. At mid-gestation the number of axons present in the nerve (218,000) already exceeded adult levels. The number of axons, nevertheless, more than doubled over the next 10-20 days, reaching a maximum of 450,000-483,000. In the last prenatal week and the first postnatal week, the number of axons declined rapidly, stabilizing at adult levels 2-3 weeks after birth. Myelination began just before birth and reached adult levels (over 95% of axons myelinated) 6-8 weeks after birth. Several mechanisms which may underlie the loss of axons are discussed.
D000818:Animals; D001369:Axons / Q000502:physiology* / Q000648:ultrastructure; D002415:Cats; D005260:Female; D005333:Fetus; D009186:Myelin Sheath / Q000502:physiology; D009900:Optic Nerve / Q000196:embryology / Q000254:growth & development* / Q000648:ultrastructure; D011247:Pregnancy