[Crustacea, general] Thin ventromedial plates, born on coxae of some pereiopods in female peracarids forming the marsupium, or brood pouch.

[Crustacea: Amphipoda] Thin plates which overlap to form a pouch beneath the pereon (marsupium) in which the eggs are hatched and the young develop (amphipods lack planktonic larvae and new-borns resemble miniature adults). These structures are located on pereopods 2-5, medial to the gills, and present only in mature females. In Gammaridea oostegites have marginal setae in the latest stages of development, whereas in Hyperiidea these setae are absent. In genus Rhabdosoma (Hyperiidea) the oostegites are reduced in size, and their function taken over by the gills.

Alternative form for Oostegites : Oostegite.