title: Mapping the Time Line of Development in Each Layer of Human Foetal Retina.
abstract: BACKGROUND
  There is need to elucidate the histological developmental stages of various layers of retina, to understand the process better and provide clinically significant insights.
  
  
  OBJECTIVE
  To study the details and chronology of in utero development of different layers of retina.
  
  
  METHODS
  To study time of appearance, differentiation and organization of all layers of central retina in different gestational age groups. Retina was studied histologically in 27 foetuses from18(th) to 34(th) weeks of gestation.
  
  
  RESULTS
  We found the period of mid gestation (19(th) -21(st) week of gestation) to be the defining time for retinal layers: The bruch's membrane was fully formed at 20(th) week of gestation; the photoreceptor layer became well defined at 21(st) week of gestation; both the nuclear layers and both the plexiform layers and the ganglion cell layer became distinct at 19(th) week of gestation. Before the 19(th) week, outer and inner neuroblastic zones separated by the neuropil were seen. Well defined nerve fibre layer and inner limiting membrane was present at 18(th) week. The outer limiting membrane was first appreciated at 32(nd) week of gestation. Foetal retinal pigment epithelium was cuboidal and filled with melanin granules while no trace of lipofuscin pigment was found under fluorescent microscope.
  
  
  CONCLUSIONS
  Detailed data on retinal histogenesis and its timeline might aid in directed differentiation of retinal cell types from stem cells for therapeutic purposes.
authors.affiliation: Assistant Professor, Department of Anatomy, Post Graduate Institute of Medical Education & Research , Chandigarh, India .
authors.forename: Tulika
authors.initials: T
authors.lastname: Gupta
authors.affiliation: Professor, Department of Anatomy, Government Medical College and Hospital , Chandigarh, India .
authors.forename: Kanchan
authors.initials: K
authors.lastname: Kapoor
authors.affiliation: Professor, Department of Anatomy, Post Graduate Institute of Medical Education & Research , Chandigarh, India .
authors.forename: Daisy
authors.initials: D
authors.lastname: Sahni
authors.affiliation: Professor, Department of Anatomy, Government Medical College and Hospital , Chandigarh, India .
authors.forename: Balbir
authors.initials: B
authors.lastname: Singh
keywords: Bruch’s membrane; Foetal retinal development; Retinal histogenesis; Retinal layers; Retinal pigment epithelium