OOCYTE MATURATION DYNAMICS IN REGIONAL AMPHIBIANS: MATHEMATICAL MODELLING AND EXPERIMENTATION

BENZAL MARIA GRACIELA; MANZANO, CAROLINA; ZELARAYÁN LILIANA ISABEL

Congreso; XXXIII JORNADAS CIENTÍFICAS ASOCIACION DE BIOLOGIA DE TUCUMAN; 2016

In amphibian oocytes, sexual steroids induce the maturation or resumption of meiosis (Prophase I) to Metaphase II as a consequence of the activation of the maturation promoting factor (MPF). The germinal vesicle breakdown (GVBD) is used as its morphological evidence. Oocyte maturation can be analyzed biologically, determining GVBD percentage of oocytes incubated in vitro in response to different sex steroids; and from mathematics, analyzing the dynamics of GVBD through mathematical models of growth that circumscribe ovarian oocytes to a population of cells that crosses the different stages of the GVBD curve. This work shows results arisen from experimentation, modeling and simulation of the dynamics of oocyte maturation induced with Progesterone (P4) and Testosterone (T) in the ovarian follicles of amphibian species not yet studied: Scinax fuscovarius, Pleurodema borellii and Physalaemus biligonigerus. Rhinella arenarum was considered a control species. In this study we proposed the Gompertz mathematical model to simulate the maturation dynamics of these amphibians. This explains the behavior of the experimental data, allowing us to estimate parameters of the model; one is associated with the maximum percentage of GVBD reached and the other to the process speed. The model includes three phases with biological significance: Lag phase, exponential phase and stationary phase. The lag phase is associated with MPF activation and in this phase, the GVBD of the three species studied is initiated before that for R. arenarum, with both steroids. The exponential phase is associated with the maturation speed (Prophase I until the beginning of Metaphase II). We concluded that S. fuscovarius is the only species in which T is the most efficient steroid inductor. Finally, the stationary phase is associated with the alignment of the chromosomes in Metaphase II, which is achieved earlier than in R. arenarum in the three species studied.