Choroid
1. sclera (sclera)
2. choroid ( choroid )
3. Schlemm's canal ( sinus venosus sclerae )
4. Arterial vascular ring ( arterial circle iridis major )
5. cornea ( cornea )
6. iris ( Iris )
7. pupil ( pupilla )
8. anterior chamber ( camera anterior bulbi )
9. posterior chamber ( camera posterior bulbi )
10. ciliary body ( corpus ciliare )
11. lens ( lens )
12. vitreous body ( corpus vitreum )
13. retina ( Retina ) and pigment epithelium
14. Optic nerve ( Nervus opticus )
15. Zonular fibers ( Fibrae zonulares )
16. Vascular supply ( Vasa ophthalmicae )
Outer eye skin ( tunica externa bulbi ): 1. +
5.Middle eye skin ( tunica media bulbi ): 2. + 6 . + 10.
Inner eye skin ( tunica interna bulbi ): 13.
The choroid , also choroid or choroid called, is the largest section of the middle eye skin ( Tunica media bulbi ). It forms the middle layer between the white skin of the eye ( sclera ) and the retina ( retina ) in the back half of the eyeball.
layers
The choroid consists of different layers:
- Lamina suprachor (i) oidea
- Lamina vasculosa
- Tapetum lucidum
- Lamina chor (i) oidocapillaris ( Choriocapillaris )
- Lamina basalis .
The lamina suprachor (i) oidea is the outermost layer and consists of elastic connective tissue and pigmented connective tissue cells.
The lamina vasculosa is the outer vascular layer facing the sclera and contains the larger arteries and veins . They are embedded in connective tissue, which is also heavily pigmented. It can be divided into two sub-layers with vessel diameters decreasing towards the retina: the Sattler layer close to the retina and the Haller layer close to the sclera.
The tapetum lucidum is not present in all mammals , for example it is absent in humans , pigs and rabbits . Most mammals, on the other hand, have a pigment-poor area in the back of their eyes. This consists either of flattened cells (e.g. in predators ), some with crystal deposits (e.g. dog) or specially arranged connective tissue fibers (e.g. horses , ruminants ). These cause a diffraction and reflection of the light and act like a residual light amplifier, since they direct the light again to the photoreceptors of the retina. Therefore, the tapetum lucidum is especially important for crepuscular species. It also causes the eyes of illuminated animals to light up in the dark.
The lamina chor (i) oidocapillaris or choriocapillaris is the terminal branching of the choroid and forms a vascular layer a few micrometers thick facing the retina, which ensures the nutrition of the outer layers of the same. The quasi-membrane consists of a fine network of fenestrated capillaries, which above the basement membrane of the pigment epithelium forms a segmented network characterized by three-finger end connections. The choriocapillaris is supplied with the layer of the next larger vessels (the Haller layer of the choroid) via lower arterioles and venules. The closely connected endothelial cells of the blood vessels and the closely connected epithelial cells of the retinal pigment epithelium (RPE) surrounding them together form the blood-retina barrier .
The lamina basalis (synonym: Complexus basalis, Lamina vitra or Bruch's membrane ) lies directly on the pigment layer of the retina and creates the connection to it.
Until the development of deep penetrating optical coherence tomography, the blood-filled choroid could not be shown with sufficient resolution in the living person. The dynamics of the choroid also in connection with the maintenance of various physiological parameters, as well as the influence on accommodation and eye growth as well as diseases such as myopia or age-related macular degeneration are not yet sufficiently understood and are the subject of current research.
Remarks
- ↑ In the current as an international standard for human anatomical terms applicable Terminologia Anatomica of 1998 instead choroid the name choroid preferred. In the Nomina Anatomica Veterinaria , which is binding for veterinarians , the alternative spelling of the choroid is followed in brackets. In the current edition of the German standard work for vertebrate zoology (Westheide & Rieger, 2010) only the spelling choroid is used.
- ↑ Debora L. Nickla, Josh Wallman: THE MULTIFUNCTIONAL choroid . In: Progress in retinal and eye research . tape 29 , no. 2 , March 2010, ISSN 1350-9462 , p. 144–168 , doi : 10.1016 / j.preteyeres.2009.12.002 , PMID 20044062 , PMC 2913695 (free full text).
- ↑ SS Hayreh: segmental nature of the choroidal vasculature. In: British Journal of Ophthalmology . tape 59 , no. 11 , November 1, 1975, ISSN 1468-2079 , pp. 631-648 , doi : 10.1136 / bjo.59.11.631 , PMID 812547 ( bmj.com [accessed January 7, 2017]).
- ^ Heimann K .: The Development of the Choroid in Man. (PDF) In: www.karger.com. Karger Publishing, December 17, 1971, accessed on January 7, 2017 (English): “The primitive choriocapillaris forms during the first 2 months; the layers, which eventually become Haller's layer and Sattler's layer. "
- ↑ Boris Považay, Bernd Hofer, Cristiano Torti, Boris Hermann, Alexandre R. Tumlinson: Impact of enhanced resolution, speed and penetration on three-dimensional retinal optical coherence tomography . In: Optics Express . tape 17 , no. 5 , March 2, 2009, ISSN 1094-4087 , p. 4134-4150 , PMID 19259251 ( nih.gov [accessed January 7, 2017]).
literature
- Paul Simoens: organ of vision , organum visus. In: Franz-Viktor Salomon, Hans Geyer, Uwe Gille (Ed.): Anatomy for veterinary medicine. 2nd, revised and expanded edition. Enke, Stuttgart et al. 2008, ISBN 978-3-8304-1075-1 , pp. 579-612.
- Wilfried Westheide, Reinhard Rieger (Hrsg.): Special zoology. Part 2: vertebrates or skulls. 2nd Edition. Elsevier - Spektrum Akademischer Verlag, Munich 2010, ISBN 978-3-8274-2039-8 .