Ovarian changes and development of the branchial placenta occurring in Jenynsia lineata (Cyprinodontiformes, Anablepidae)

DI CESARE, LUCA; BARBEITO, CLAUDIO G.; SANTAMARÍA MARTÍN, CARLOS; MONTES, MARTÍN M.; URIBE, MARI C.; PLAUL, SILVIA E.

JOURNAL OF MORPHOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2023 vol. 284

0362-2525

In viviparous teleosts, intraovarian gestation occurs intrafollicularly, as in poeciliids,or intraluminally, as in goodeids and anablepids. Furthermore, there are two differentforms of embryonic nutrition: lecithotrophy and matrotrophy; depending on thespecies, these can be exclusive or coexist during gestation. In matrotrophic species,nutrients are transmitted from the mother to the embryo and are especiallyimportant in species with intraluminal gestation. Jenynsia lineata is a South Americanviviparous teleost with intraluminal gestation, characterized by eggs with scarceyolk, which is resorbed when embryos are 6 mm long, thus developing a branchialplacenta. Using histological, histochemical, and immunohistochemical techniques,the present study describes the characteristics and changes of the ovarian mucosa inJ. lineata during gestational and nongestational phases, and analyzes the embryonicpharyngeal epithelium in the branchial placenta. The ovaries of 30 adult femalespecimens were processed using histological techniques and stained withhematoxylin‐eosin, Masson´s trichrome, and Alcian Blue pH 2.5/periodic acid Schiffreagent. To detect cell proliferation, we used antiproliferating cell nuclear antigenantibody. In nonpregnant females, eosinophilic granular cells (EGCs) and lymphocytes were identified in the lamina propria of the tunica mucosa, and melanomacrophage centers (MMCs) and fibroblasts were identified adjacent to tissue debris inthe ovarian folds´. In the cellular debris, an embryo in resorption was observed. Inpregnant females, the ovarian mucosa has thin vascularization branches entering theopercular chamber of the embryos, in close contact with the forming gill processes,thereby establishing a branchial placenta. Active cell replacement was observed inthese ovarian branches. The identification of fibroblasts, lymphocytes, EGCs, andMMCs adjacent to tissue debris could indicate that these cell types are involved inthe embryonic resorption process. Considering the new data obtained in this studyon the branchial placenta of J. lineata, we conclude that cell proliferation could beinvolved in the development of maternal–embryonic interaction.