Alterations in the Morphology of the Testis and Epididymis Caused by the Consumption of Hyperlipidic Diets in Wistar Rats

Abstract

Obesity is considered a metabolic disease, in which leptin is used as an indicator of energy in the body. This hormone, in turn, is related to the neuroendocrine regulation of the reproductive axis. However, leptin excess secretion due to obesity can have a negative effect on reproduction. Overweight and obesity were induced through high-calorie diets. Lee and gonadosomatic indices were determined to characterize the model and degree of reproductive development in the testis and epididymis. Sperm quality was analyzed using spermatobioscopy. Morphometry was analyzed through histological analysis. The changes described affect testicular function in hormone and sperm production. Exposure of 3-month-old male rats to diets with different fat contents (10% and 60%) induced both overweight and obesity. The animals showed morphological alterations, both testicular and epididymal, the latter being more sensitive to dietary changes by modifying the epididymal index, morphometric parameters (in both organs), and a decrease in cilia length. These changes induced a reduction in sperm viability, as well as an increase in malformed spermatozoa. In conclusion, both overweight and obesity have effects on male reproduction by modifying the morphology and physiology of reproductive organs.

Keywords: epididymis; histomorphometry; obesity; overweight; sperm quality; testis.

Figure 1

Histological sections of the testis. Control (A,B), DIO (C,D), DIOb (E,F). The seminiferous tubules of the overweight and obese animals show vacuolization, which generates a displacement of the seminiferous epithelium towards the tubule lumen in some tubules, folding of the basement membrane is observed, and the shape of the tubule is irregular when compared with the control group. Hematoxylin–Eosin technique. Thin arrow: seminiferous tubule; Thick arrow: vacuolization; Arrowhead: basement membrane. Bar 100 µm micrograph (A,C,E); Bar 20 µm micrograph (B,D,F).

Figure 2

Histological sections of the epididymis. Control (A–C), DIO (D–F), DIOb (G–I). Sections of the three regions of the epididymis, caput (A,D,G), corpus (B,E,H), and cauda (C,F,I). In the three sections of the epididymis in the control group, it is observed that along the epididymis, there is a decrease in the size of the epithelium, in the caput region, with an abundance of cilia. Spermatozoa are observed in the center of the tubule. Both the overweight and obesity groups show a decrease in the above-mentioned parameters, as well as an increase in vesicles in the epithelium of the treated animals. Changes are observed in the number and length of cilia, which decrease significantly in the corpus and cauda. In the obese animals, the changes are more drastic in terms of size and number in the corpus and cauda regions. Masson’s trichrome. Thin arrow: cilia; Thick arrow: epithelium. Bar 20 µm.

Figure 3

Changes that occur in the clear and principal cells of the epididymis, as well as the effect on sperm viability and morphology due to overweight and obesity in Wistar rats. A low concentration of testosterone and high leptin due to the increase in adipose tissue in obesity generate changes in the length of the cilia in the principal and clear cells of the epididymis, particularly in the corpus and cauda parts, which is proposed to be due to an adaptive mechanism. Although the cells try to compensate for the degenerative effect on the cell by lengthening the cilia, under conditions of overweight, in the end, obesity causes the cilia to be lost in these cells, and seminal quality is affected, decreasing viability and increasing abnormalities in the midpiece and flagellum of the sperm, created in BioRender.com, 2025.