Cartilaginous fish are the oldest extant jawed vertebrates and the oldest line to have placentae. Their pivotal evolutionary position makes them attractive models to investigate the mechanisms involved in the maternal-fetal interaction. This study describes the tissue expression of the cytokine @entity1192 ( @entity1192 , @entity1356 and its specific membrane receptor, @entity1192 receptor type I (IL-1R tI) in a placental cartilaginous fish, the smoothhound shark, Mustelus canis. The presence of this cytokine has been reported in many @entity1 placentae, as well as in the placenta of a squamate reptile and this study extends these observations to the cartilaginous fishes. The uteroplacental complex in @entity14476 consists of a yolk sac modified into a functional yolk sac placenta and complimentary uterine attachment sites. Immunohistochemistry for @entity1192 , @entity1356 and the receptor reveals leucocytes of both the mother and fetus to be positive, as well as the apical aspect of paraplacental cells and the apical vesicles in the umbilical cord epithelium. Yolk sac endoderm is also positive with all the stains while the ectoderm is positive only for @entity1192 . Immunoreactivity in the uterine epithelium was obtained for @entity1192 and the receptor. The egg envelope is always negative. In light of the recent finding of @entity1356 gene in a cartilaginous fish and of the high level of conservation of proteins implicated in @entity1192 action, our data suggest that @entity1192 system is a key mediator of the materno-fetal interaction since the oldest extant placental vertebrates.

The XXXX ) system in the uteroplacental complex of a cartilaginous fish, the smoothhound shark, Mustelus canis.

@entity1 :: ('9606', 'Species') :: ['mammalian'] @entity14476 :: ('63405', 'Species') :: ['M. canis'] @entity1192 :: ('3552', 'Gene') :: ['IL-1 alpha', 'IL-1', 'interleukin-1', 'IL-1) alpha'] @entity1356 :: ('3553', 'Gene') :: ['IL-1 beta']
@entity1356 :: (3553,Gene) :: ['interleukin 1 (IL-1']
