Pseudopupil
{{short description|Dark spot on the compound eyes of some invertebrates}}
File:Prohierodula picta Mantis (cropped).jpg showing the black pseudopupil in its compound eyes]]
File:Pseudosquilla.JPG has three regions, each with its own pseudopupil.]]
In the compound eye of invertebrates such as insects and crustaceans, the pseudopupil appears as a dark spot which moves across the eye as the animal is rotated.{{cite journal |author1=M. F. Land |author2=G. Gibson |author3=J. Horwood |author4=J. Zeil |year=1999 |title=Fundamental differences in the optical structure of the eyes of nocturnal and diurnal mosquitoes |journal=Journal of Comparative Physiology A |volume=185 |issue=1 |pages=91–103 |doi=10.1007/s003590050369 |s2cid=9114187 |url=http://web.neurobio.arizona.edu/gronenberg/nrsc581/eyedesign/differencesnightdaymosquitoes.pdf |access-date=2008-07-27 |archive-url=https://web.archive.org/web/20160304134808/http://web.neurobio.arizona.edu/gronenberg/nrsc581/eyedesign/differencesnightdaymosquitoes.pdf |archive-date=2016-03-04 |url-status=dead }} This occurs because the ommatidia that one observes "head-on" (along their optical axes) absorb the incident light, while those to one side reflect it.{{cite journal |author1=Jochen Zeil |author2=Maha M. Al-Mutairi |name-list-style=amp |year=1996 |title=Variations in the optical properties of the compound eyes of Uca lactea annulipes |journal=The Journal of Experimental Biology |volume=199 |issue=7 |pages=1569–1577 |doi=10.1242/jeb.199.7.1569 |url=http://jeb.biologists.org/cgi/reprint/199/7/1569.pdf |pmid=9319471}} The pseudopupil therefore reveals which ommatidia are aligned with the axis along which the observer is viewing.
Pseudopupil analysis technique
The pseudopupil analysis technique is used to study neurodegeneration in insects like Drosophila, where specimens are genetically engineered with transgenes to model neurodegenerative diseases such as Huntington's chorea. An adult Drosophila eye consists of nearly 800 unit ommatidia which are repeated in a symmetrical pattern. Each ommatidium contains 8 photoreceptor cells, each of which forms a rhabdomere (rhabdomeres 7 and 8 overlap vertically; therefore, only rhabdomere 7 is visible externally). Neurodegeneration leads to loss or degradation of photoreceptors.{{Cite book|last1=Song|first1=Wan|last2=Smith|first2=Marianne R.|last3=Syed|first3=Adeela|last4=Lukacsovich|first4=Tamas|last5=Barbaro|first5=Brett A.|last6=Purcell|first6=Judith|last7=Bornemann|first7=Doug J.|last8=Burke|first8=John|last9=Marsh|first9=J. Lawrence|chapter=Morphometric Analysis of Huntington's Disease Neurodegeneration in Drosophila |date=2013|title=Tandem Repeats in Genes, Proteins, and Disease|volume=1017|pages=41–57|doi=10.1007/978-1-62703-438-8_3|issn=1940-6029|pmid=23719906|series=Methods in Molecular Biology|isbn=978-1-62703-437-1|url=https://escholarship.org/uc/item/46p4153p}} By visualizing and counting the intact rhabdomeres, degradation level can be measured. Thus, analyzing the pseudopupil can permit empirical study of neurodegeneration.
References
{{reflist|2}}
{{Commons category|Pseudopupils}}
{{vision in animals}}
{{eye-stub}}