Leydig's organ (named after the German histologist
Franz Leydig who first described it in 1857) is a unique structure found only in some, but not all,
elasmobranchs (
shark
Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...
s and
rays). Nestled along the top and bottom of the
esophagus
The esophagus (American English), oesophagus (British English), or œsophagus (Œ, archaic spelling) (American and British English spelling differences#ae and oe, see spelling difference) all ; : ((o)e)(œ)sophagi or ((o)e)(œ)sophaguses), c ...
, it produces
red blood cells, as do the
spleen and special tissue around the
gonad
A gonad, sex gland, or reproductive gland is a Heterocrine gland, mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gon ...
s. Heterophilic and
eosinophilic granulocytes are produced, closely resembling structures of mammalian
plasma cells. Leydig's organ is part of the immune system.
[Mattisson, A., & Faänge, R. (1982). The Cellular Structure Of The Leydig Organ In The Shark, ''Etmopterus spinax'' (L.). The Biological Bulletin, 162(2), 182–194. doi:10.2307/1540813]
Notes
References
*
Fish anatomy
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