Development and teratology of sensory organs Anna Mac Gillavry Danylevska 22.5.2023 diencephalon 3rd brain ventricle Development of the eye ectoderm mesenchyme lens placode optic cup stalk of optic cup intraretinal space of optic cup Development of the optic cup and the lens outer layer of cup intraretinal space inner layer of cup stalk of optic cup lumen of stalk of optic cup lens vesicle ectoderm neuroectoderm (wall of diencepalon) intraretinal space diencephalon wall lens vesicle lumen of stalk of optic cup anterior epithelium of lens ectoderm eyelid pigmented layer of retina nervous layer of retina intraretinal space mesenchyme + retinal pigmented layer retinal nervous layer camera oculi ant. eyelid ectoderm conjunctival sac mesenchyme Eye abnormalities • Coloboma – in most cases coloboma iridis, frequently associated with other eye abnormalities; optic nerve coloboma is linked to PAX2 gene mutations – renal coloboma syndrome – autosomal dominant https://atrl.net/forums/topic/430624-girl-comes-forward-claiming-to-be-the-missing-madeleine-mccann/ • Iridopupillary membrane • Sclerocornea • Peters anomaly • Congenital cataracts – genetically determined or rubella virus! • Persistent hyaloid artery (in 3 % of full term infants) – amblyopia, vitreous haemorrhage, retinal detachment • Microphtalmia – 1,5-1,9 in 10000, cytomegalovirus, toxoplasmosis • Anophtalmia – 0,18-0,4 in 10000 • Congenital aphakia/aniridia – mutation in PAX6 results in aniridia; WAGR syndrome – microdeletion in chromosome 11 (PAX6 and WT1) • Cyclopia and synophtalmia (loss of midline tissue holoprosencephaly) – alcohol, maternal diabetes, mutations in SHH and abnormalities in cholesterol metabolism Development of the inner ear otic placode mesenchyme ectoderm otic pit dorsal aorta otic pit wall of rhombencephalon otocyst the 1st ectodermal cleft Development of the membranous labyrinth utricular part of otocyst saccular part of otocyst tubular process of sacculus T. W. Sadler, Langman’s medical embryology, 12th edition Development of the middle ear Meckel‘s cartilage rhombencephalon utriculus sacculus 1st ectodermal cleft middle ear ossicles wall of inner ear primitive cavum tympani wall of inner ear Development of the external ear T. W. Sadler, Langman’s medical embryology, 14th edition External ear defects • Anotia • Microtia - (1 in 6000-12000) usually one ear is affected, the external accustic meatus is absent or narrowed – conductive hearing loss • Preauricular appendages and pits All of the frequently occurring chromosomal syndromes and most of the less common have ear anomalies as one of their characteristics!!! (Langman’s medical embryology, T. W. Sadler, 14th edition, p. 359) Anotia | Children's Hospital of Philadelphia (chop.edu) Congenital hearing loss Sensorineural (hair cells or auditory nerve ganglia) vs. conductive (most commonly stapes) - genetic factors: 50% cases (e.g. Treacher Collins syndrome, Down syndrome - perinatal infections: rubella virus, cytomegalovirus, herpes simplex - prematurity - maternal diabetes - isotretinoin!