The morphofunctional state of the fetal thyroid gland in maternal-fetal infections caused by Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae

Abstract

Aim – experimental modelling and determination of the morphofunctional state of the thyroid gland of a rat fetus in maternal-fetal infections caused by E. coli, S. aureus and K. pneumoniae. Material and methods. We conducted a controlled experimental study with block randomization on 85 female Wistar Albino Glaxo rats, which, depending on the group assigned randomly, were infected or not with E. coli, S. aureus and K. pneumoniae before pregnancy with subsequent pathomorphological examination of 37 thyroid glands obtained from rats’ fetuses. The set of methods was applied: histological – HE and Mallory staining; indirect immunofluorescence: moAb to T4, types I and III collagen, IL-6, and TNF; histomorphometry using ImageJ software. Statistical analysis was performed with the R environment and packages “ggplot”, “dplyr”, “pastecs”, “graphics” for Shapiro–Wilk test, Bartlett’s test, Box-Cox method, ANOVA, and plotting. The null hypothesis was rejected in cases when an error probability (P) did not exceed the type I error set at 0.001 (P < 0.001). Results. In the thyroid glands of fetuses obtained from mothers infected with E. coli, S. aureus and K. pneumoniae, in comparison with the control group, a statistically significant increase in the following morphofunctional parameters was determined: the diameter and area of the follicle, the area of the colloid, the height and area of the thyrocyte, the intensity and area of the fluorescence of the follicular thyrocytes and colloid, in samples labeled MoAb to T4, the intensity of the fluorescence of collagen types I and III; a decrease in the area of the nucleus in relation to the area of the cytoplasm, which was reflected in a decrease in the NCR index. The most pronounced differences in morphological and functional parameters from the norm were found in the thyroid gland of fetuses from mothers infected with S. aureus. Conclusions. The revealed changes in the morphofunctional parameters of the thyroid gland of a rat fetus, which experienced the influence of maternal-fetal infections caused by E. coli, S. aureus and K. pneumoniae, are unidirectional and statistically significantly different from those recorded during physiological organogenesis. They correspond to an increase in the gland’s secretory activity and indicate the acceleration of organ’s maturation.