Fig. 4

Imbalanced renin-angiotensin system in the testis of COVID-19 critically ill patients. a–d Initial categorization of COVID-19 patients according to the most advanced germ cell in the seminiferous epithelium: phase 1 (P1), phase 2 (P2), and phase 3 (P3). Toluidine-blue counterstaining (scale bars = 50 μm). a Control patients showing elongated spermatids (E). b COVID-19 patients showing elongated spermatids (E), spermatocytes (Spc), and spermatogonial cells (Spg). c COVID-19 patients displaying spermatocytes (Spc) and spermatogonial cells (Spg). d COVID-19 patients presenting spermatogonial cells (Spg) only. e Positive correlation between patient’s phases and the time frame from ICU admission to death (Spearman’s rho = 0.6862; p = 0.0197). f–i Immunostaining of ACE2 in the testis of control (f) and COVID-19 patients (g–i) (scale bars = 50 μm). h’ Negative control, omitting the primary antibody. Red: Alexa-594; blue: dapi; green arrowheads: Leydig cell; red arrowheads: spermatogonial cell; blue arrowheads: Sertoli cell. j Heat map of the evaluated genes related to the renin-angiotensin system. The colors compare COVID-19 patients to controls. Green: lower expression than controls. Red: higher expression than controls. k–n Immunostaining of AGT1R in the testis of control (k) and COVID-19 patients (l–n). Purple arrowheads: peritubular myoid cells; green arrowheads: Leydig cells; orange arrowhead: macrophages (scale bars = 50 μm). o ELISA assay for angiotensin II (t-test; two-tailed; infected groups vs control; *p < 0.05). P1, P2, P3: phases 1, 2, and 3 of the COVID-19 patients, respectively. ST, seminiferous tubule; IC, intertubular compartment. Individual values can be found at https://doi.org/10.6084/m9.figshare.16777786.v8