Meeting Abstract

P2.152  Sunday, Jan. 5 15:30  Structural characterizations of the Poeciliopsis fish placenta PANHUIS, T.M.*; KWAN, L.; FRIS, M.; TUHELA-REUNING, L.; RODD, F.H.; ROWE, L.; Ohio Wesleyan University; University of Toronto; Ohio Wesleyan University; Ohio Wesleyan University; University of Toronto; University of Toronto tmpanhui@owu.edu

Fish species in the genus Poeciliopsis are livebearers (i.e. viviparous) and vary in their degree of embryonic maternal provisioning. Variation in Poeciliopsis maternal provisioning has been quantified using the matrotrophic index (MI) and species fall into three MI categories: none, (lecithotroph; MI<0.7), moderate matrotroph (0.7<MI<5), and extensive matrotroph (MI>5). Regardless of reproductive-trophic mode, individual Poeciliopsis embryos develop within a maternal ovarian follicle until birth. In matrotrophic species, however, the follicle is specialized to act as a placental-like tissue aiding in embryonic nutrient transfer. In addition, embryonic surface structures and the pericardial sac are believed to efficiently absorb maternal nutrients. The goal of this project is to characterize and compare the maternal and embryonic placental structures across a range of Poeciliopsis species, which vary in their MI value. Surface structure variation of the maternal follicle and embryonic body and sac was examined using scanning electron microscopy. Quantification of follicle thickness variation between species was analyzed with a sectioning, staining, and Image J measurement approach. Our results underscore the placenta structural differences between Poeciliopsis species and shed light on surface structures and follicle remodeling necessary for different modes of Poeciliopsis viviparity.