Repeated hyperstimulation affects the ultrastructure of mouse fallopian tube epithelium

Abstract

Controlled ovarian hyperstimulation (COH) is routinary used in assisted reproductive technologies (ARTs) to increase the yields of mature oocytes. The possibility that patients with a history of failures or poor-responders may develop side-effects following these treatments is still debated. Epidemiological studies reported controversial results about pregnancy outcome and the risk of developing gynecological cancers. By using a mouse model, here we compared the ultrastructural features of fallopian tubes (FTs) obtained from mice undergoing or not (control, CTR) four (4R) and eight (8R) rounds of gonadotropin stimulation. Although the morphological characteristics of oviductal layers seemed unaffected by repeated treatments, dose-response ultrastructural alterations in the ampulla appeared in the 4R group and even more in the 8R group. The targets were oviductal ciliated (CCs) and non-ciliated (NCCs) cells, which showed damaged mitochondria and glycogen accumulations in the cytoplasm. The drastic reduction of CCs, evident after 4R, was supported by the absence of cilia. After 8R, glycogen granules were significantly reduced and massive degeneration of mitochondria, which appeared swollen and/or vacuolated, occurred in NCCs. Moreover, disintegrated mitochondria were found at the periphery of mitophagic vacuoles with evident signs of cristolysis. The morphometric analysis evidenced a significant increase in the density and frequency of damaged mitochondria after 4R and 8R. The absence of cilia, necessary to sustain oviductal transport of oocytes, spermatozoa and embryos, may originate from either mitochondrial dysfunction or glycogen consumption. These results suggest that repeated COH treatments could induce alterations impairing fertilization and embryo transport toward the uterus.

Effects of Repeated Ovarian Stimulation on Ovarian Function and Aging in Mice

“…These results showed that repeated ovarian stimulation prolongs the luteal phage in which the CL develops. A recent report showed that repeated ovarian stimulation at 16-day intervals alters the estrus cycle, inducing uterine cell proliferation in mice (Antonouli et al, 2020). In monkeys, however, observations of the uterus after 5 years of repeated ovarian stimulation did not result in significant changes in the endometrium (Yan et al, 2017).…”

Continue or quit? -- Recommendations for repeated controlled ovarian stimulation therapy

“…The small number of patients undergoing COS > 5 times in the clinic makes statistical analysis di cult, whereas a distinctive study can be designed to analyze them in an animal model. Antonouli et al [20] reported that the oviducts of mice receiving 4 and 8 gonadotropin stimulation did not perceive signi cant morphological changes but underwent signi cant ultrastructural alterations, including a dramatic decrease in ciliated cells and massive mitochondrial degeneration compared to controls (who did not receive stimulation). These alterations were more pronounced at 8 than 4 times, which may negatively affect the fertilization process and embryo transport to the uterus.…”

Deeply in Plasticenta: Presence of Microplastics in the Intracellular Compartment of Human Placentas

“…For light microscopy (Zeiss Axioscope, Gottingen, Germany) observation, methylene blue staining (Sigma-Aldrich) was used for coloration of semithin sections (1 μm); for TEM (Zeiss EM10, Oberkochen, Germany), operating at 60 kV, ultrathin sections (90–100 nm) were cut with a diamond knife, mounted on copper grids, contrasted with Uranyless (Uranyl acetate alternative) (TAAB Laboratories Equipment Ltd., Aldermaston, UK) and lead citrate (Electron Microscopy Sciences), and photographed. Further details of sample preparation for TEM observations have been reported elsewhere, in our previous studies [ 41 , 42 ].…”