SEASONAL CHANGES IN THE OVARY OF MYIOPSITTA(PSITTACIFORMES, AVES)

NETRI MARÍA CECILIA; ARIAS MARÍA NANCY; BARBEITO CLAUDIO G.; CARRIL JULIETA

Jornada; XXIV Jornada Anual de la Sociedad Argentina de Biología (SAB); 2022

Sociedad Argentina de Biología (SAB)

The aplasia of the right ovary and oviduct during embryological development is one of many adaptations associated with body weight loss and flight in birds. The appearance of the remaining left ovary in adults may change based on reproductive seasonality. The monk parakeet Myiopsitta monachus is one of the few species of Psittaciformes considered an agricultural pest. It has spread in its native range in Argentina and throughout the world. We aim to study the morpho-histology of the ovary of Myiopsitta during breeding (October–December) and non-breeding (January–August) seasons. Four adult specimens (two from each season) were analyzed. Ovaries were dissected and fixed in 4% formalin and preserved in 70% alcohol solutions. They were measured with a caliper (accuracy: 0.01 mm) and a weighing scale (accuracy: 0.001 g) and processed for histological techniques: hematoxylin–eosin, Gomori trichrome, periodic acid Schiff/hematoxylin (PAS), and orcein. In the non-breeding season, the ovaries are 6.31 mm long by 5.78 mm wide, and they weigh 0.087g on average. They are triangular and have poorly defined follicles separated by slight furrows. While in the breeding season, the ovaries increase their size. They reach to measure 8.87 mm long by 6.35mm wide, and they weigh up to 0.113 g on average. Their appearance resembles a bunch of grapes, with follicles protruding from the surface and delimited by deep furrows. Histologically, a single cuboidal epithelium surrounds the ovaries. They have two distinct zones: the outer cortex with follicles at different developmental stages, separated by a thin connective tissue network with collagen fibers and a few elastic fibers; and the inner stroma composed of wellvascularized and innervated connective tissue. Growing follicles show PAS positivity in the basal membrane and the follicular epithelium. The external and internal thecas have collagen fibers arranged in concentric layers. Non-breeding season ovaries have primordial, primary, growing (previtellogenic), and non-bursting atretic (lipoidal and lipoglandular-invasive) follicles. While breeding season ovaries show the highest follicular development having several growing (previtellogenic) and vitellogenic follicles. They also have few preovulatory, postovulatory, non-bursting (lipoglandular-invasive), and bursting atretic follicles. The ovary of Myiopsitta is similar to that of other bird species with marked reproductive seasonality. This study represents the first of a series expected to set the baseline for future studies useful in veterinary medicine and pest control fields.