title: Topography of the "vitreous structures" (tractus; membranelles) with respect to the layers of embryonal blood vessels.
abstract: BACKGROUND
  It is believed that the vascular or primary vitreous, with the exception of the later Cloquet's canal, gradually disappears and is substituted by the avascular or secondary vitreous. It is known that it is possible topographically to objectify mats of fibril concentrations (membranelles or tractus) of stronger light reflection inside the adult vitreous. These concentrations open up in the shape of a funnel from the papilla or Cloquet's canal towards the front of the vitreous.
  
  
  METHODS
  This was a light microscopy investigation on human eyes between the embryonal stage of 3.2 cm and the fetal stage of 12.5 cm and eyes 8 months and 2 years old with persistent vessels of the vitreous.
  
  
  RESULTS
  The investigation showed that at the embryonal stage, the vitreous body is threaded from behind by branches (mats) of the hyaloid artery and from in front by vessels (mats) that go over the rim of the optic cup, i.e., the later vitreous base. Vitreous structures, in the form of horsetail-shaped fibril concentrations, could already be observed histologically in the fetal stage with the disappearance of embryonal blood vessels. These structures begin in the vitreous base, go into the vitreous, run parallel to the retina, and then go to the back of the vitreous and towards the lens. The physiological mats of vitreal fibril concentrations (membranelles or tractus) and the pathological branches of the persistent hyaloid artery, topographically correspond to the mats of the obliterated embryonal blood vessels of the vitreous. These mats grow in relation to the bulbous growth.
  
  
  CONCLUSIONS
  In these investigations an attempt has been made to clarify the question of which embryonal blood vessels. which embryonal and fetal lengths, which different physiological tractus of the vitreous body and which different pathological features of the persistent hyaloid artery correspond.
authors.forename: H
authors.initials: H
authors.lastname: Pau
mesh_terms: D001158:Arteries / Q000196:embryology*; D005123:Eye / Q000098:blood supply / Q000196:embryology; D005333:Fetus / Q000033:anatomy & histology*; D005865:Gestational Age; D006801:Humans; D014822:Vitreous Body / Q000033:anatomy & histology* / Q000098:blood supply* / Q000196:embryology