Avaliação histomolecular da dimensão fractal e da remodelação da matriz extracelular durante o desenvolvimento ovariano de fetos bovinos

Abstract

The reproductive physiology of female mammals is different due to their estrous phase, the formation of female gametes and ovarian follicles that started in the prenatal period. The appearance of preantral stages in the ovary has a species-specific temporal pattern. In females of Bos taurus indicus, studies have already shown that primordial, primary and secondary follicles appear close to 90, 120 and 150 days of gestation, respectively. Although studies have focused on remodeling the extracellular matrix (ECM) during the formation and functionality of adult ovaries, there is a lack of understanding about the mechanisms that control the formation of preantral follicles during pregnancy. The aim of the study was to characterize the histomolecular phenotype of ECM remodeling through the fractal dimension (FD), quantification of collagen and profile of transcripts involved with remodeling of ECM in ovaries of bovine fetuses associated with the temporality of formation of pre-antral follicles. Thus, in order to investigate tissue remodeling along fetal ovarian development, fetal ovaries were used to quantify FD, total collagen and relative mRNA abundance of genes related to ECM remodeling (COL1A1, COL1A2, COL4A1, MMP2, MMP9, MMP14, TIMP1 and TIMP2). For this purpose, pairs of fetal ovaries were obtained from Bos taurus indicus females at 60, 90, 120 and 150 days of gestation in a slaughterhouse, one of which was destined for the extraction of total RNA and further investigation of the target transcripts and the other for collagen analysis. total and FD. The present study demonstrated that after 120 days there was a greater area of total collagen in the fetal ovary. In the staining analyzes in hematoxylin eosin (HE), the FD was lower at 150 days when compared to 60 days of gestation, however, it presented an inverse pattern in the picrosirius staining. The expression of the target genes for the relative abundance of mRNA transcripts for COL1A1, COL4A1, MMP2, MMP14, TIMP1 and TIMP2 was greater at 150 days compared to day 60. It is concluded that the fractal dimension reflects the morphological changes during structural organization of fetal ovarian tissue and that the expression of genes related to ECM remodeling is modulated throughout pregnancy in fetal bovine ovaries.