Zinc (in the form of Zn²⁺) is necessary for male fertility. Both Zn²⁺ quantity and its localisation have been detected in seminal plasma and ejaculated spermatozoa, suggesting its active uptake via zinc import transporters (ZIPs). Immunofluorescence was used to characterise the expression and localisation of three distinct types of ZIP transporters in ejaculated spermatozoa of normo- and asthenozoospermic sperm samples. ZIP6, ZIP10 and ZIP14 showed heterogeneous sperm cell expression and different compartmental distribution. In both types of sperm samples, ZIP6 and ZIP14 were predominantly localised in the sperm head, while ZIP10 was found along the sperm tail. Compartmental localisation of ZIPs in asthenozoospermia was not changed. However, regarding sub-compartmental localisation in sperm head regions, for ZIP6 asthenozoospermia only decreased its acorn/crescent-like pattern. In contrast, ZIP14 immunostaining was altered in favour of crescent-like, as opposed to acorn-like and acorn/crescent-like patterns. The specific ZIPs localisation may reflect their different roles in sperm cell integrity and motility and may change over time. This is the first report of their specific compartmental and sub-compartmental localisation in ejaculated human sperm cells. Further research will lead to a greater understanding of the roles of ZIPs in sperm cell biology, which could positively influence procedures for human infertility therapy.

Background and Objectives: Numerous risk factors for both female and male fertility have been established including age, ovarian reserve, infertility cause, occupational and lifestyle factors. The objective of our study was to determine the influence of occupational and lifestyle factors on assisted reproduction (ART) outcomes at a Serbian referral tertiary center. Materials and Methods: The study included all consecutive infertile couples undergoing ART at the Clinic for Ob/Gyn University Clinical Center Belgrade, from January 2019 to January 2022. Inclusion criteria comprised primary and unexplained infertility, age ≤ 45 years, body mass index ≤ 30 kg/m² and undergoing fresh autologous ART cycles. All patients filled in the socio-epidemiological questionnaire that analyzed their lifestyle and habits. Medical history data and data regarding the current ART cycle were taken from patient records. The primary outcome was clinical pregnancy. Results: Our study included 501 couples (women and men) with infertility undergoing ART. Clinical pregnancy was achieved in 22.2% of examined patients. Achieving clinical pregnancy in the ART cycle for women was associated with younger age and use of vitamins, minerals, and trace elements, whereas younger age and absence of chronic illnesses were the most important factors for male partners. When women and men were assessed together as couples, achieving clinical pregnancy correlated only with the use of vitamins, minerals and trace-elements by both partners. Conclusions: This study confirmed that some occupational and lifestyle factors were associated with clinical pregnancy after ART in patients with unexplained primary infertility and normal BMI.

Thyroid hormones play an important role in both testis development and spermatogenesis. While hypothyroidism has been known to generally induce metabolic suppression, lower respiration rate, and reduce free radical formation, recent studies reported an increased production of reactive oxygen species (ROS). First line of antioxidant defense in testes is comprised of two isoforms of superoxide dismutase (SOD), CuZnSOD and MnSOD differently localised in cell. This study aimed to investigate the effects of hypothyroidism on the expression, localisation, and activity of these two SOD isoforms during spermatogenesis. Hypothyroidism was induced in two-month-old male Wistar rats by 0.04% methimazole in drinking water for 7, 15, and 21 days, while euthyroid control group drank tap water. CuZnSOD protein expression was decreased after 15 and 21 days while its activity was decreased by 40% in all examined time points of methimazole treatment in comparison to euthyroid control. At the same time, neither MnSOD protein expression nor its activity was changed by treatment. However, cell and stage-specific CuZnSOD and MnSOD immunoexpression in the rat testes were changed in hypothyroidism and may contribute to the altered spermatic characteristics. Our results suggest that changes in CuZnSOD and MnSOD expression play role in redox disbalance leading to hypothyroidism-induced maturation arrest of spermatogenesis.

Introduction/Objective. Male infertility accounts for approximately 40% of infertility cases, with asthenozoospermia affecting nearly one in five infertile men. Beyond conventional semen parameters, nuclear DNA organization and chromatin accessibility provide deeper insight into sperm quality. Zinc transporters ZIP6 and ZIP14 have been implicated in chromatin stabilization and zinc homeostasis, potentially essential to sperm maturation and fertilization competence. Methods. Semen samples from normozoospermic and asthenozoospermic men undergoing intrauterine insemination were purified by density gradient. ZIP6 and ZIP14 were detected by immunofluorescence, nuclear DNA visualized by using Sytox Orange. Expression levels, nuclear area, and staining intensity were quantified in ImageJ, and analyzed using Kruskal-Wallis test with Dunn's post-hoc correction (p ≤ 0.05). Results. ZIP6 immunopositivity was significantly reduced in asthenozoospermic compared to normozoospermic samples, while ZIP14 expression remained stable. Nuclear area and overall Sytox Orange intensity did not differ significantly between transporter-positive and -negative sperm, though ZIP6-positive asthenozoospermic cells showed a modest reduction in nuclear surface area. Normozoospermic ZIP14-negative spermatozoa displayed lower Sytox Orange fluorescence than ZIP6-negative cells, suggesting focal differences in chromatin accessibility between transporter-defined subpopulations. Conclusion. ZIP6 expression reflects sperm maturation and functional competence, while ZIP14 remains constitutively stable. Both transporters may serve as molecular markers for selecting high-quality sperm in assisted reproduction, particularly in populations exposed to occupational stressors that compromise DNA integrity.