part of ostium lateral ostial inflow tract Hemolymph inflow tract of the dorsal vessel (Lehmacher et al., 2012). It is formed by a pair of ostial cells flanking a pore through which hemolymph enters the dorsal vessel (Lehmacher et al., 2012). The pore can be closed to prevent outflow during the systolic phase (Lehmacher et al., 2012). Ostia have identical morphology at the adult and larval stages (Lehmacher et al., 2012). fly_anatomy.ontology FBbt:00003166 lateral valve ostiolar valve ostial valve cell cluster organ dorsal vessel