There is a global trend of declining fertility among people of childbearing age and mankind is confronted with great challenges of fertility problems. As a result, fertility preservation technology has emerged. Fertility preservation involves interventions and procedures aimed at preserving the patients\' chances of having children when their fertility may have been impaired by their medical conditions or the treatments thereof, for example, chemotherapy and/or radiotherapy for cancer. The changes in patients\' fertility can be temporary or permanent damage. Fertility preservation can help people diagnosed with cancer or other non-malignant diseases. More and more fertility preservation methods are being used to preserve the fertility of cancer patients and protect their reproductive organs from gonadotoxicity. Fertility preservation may be appropriate for young patients with early-stage cancers and good prognosis before they undergo treatments (chemotherapy and/or radiotherapy) that can negatively affect their fertility. It is also appropriate for patients with chronic conditions or those who have encountered environmental exposures that affect their gonadal function. Fertility preservation methods include oocyte cryopreservation, embryo cryopreservation, and ovarian tissue cryopreservation (OTC) for women and sperm freezing and testicular tissue freezing for men. The survival rates of children and adolescents diagnosed with malignant tumors have been steadily increasing as a result of advances in cancer treatments. Cryopreservation of oocytes and sperm is recognized as a well-established and successful strategy for fertility preservation in pubertal patients. OTC is the sole option for prepubertal girls. On the other hand, cryopreservation of immature testicular tissue remains the only alternative for prepubertal boys, but the technology is still in the experimental stage. A review showed that the utilization rate of cryopreserved semen ranged from 2.6% to 21.5%. In the case of cryopreserved female reproductive materials, the utilization rate ranged from 3.1% to 8.7% for oocytes, approximately from 9% to 22.4% for embryos, and from 6.9% to 30.3% for ovarian tissue. When patients have needs for fertility treatment, cryopreserved vitrified oocytes are resuscitated and in vitro fertilization-embryo transfer (IVF-ET) was performed to help patients accomplish their reproductive objectives, with the live birth rate (LBR) being 32%. On the other hand, when cryopreserved embryos are resuscitated and transferred, the LBR was 41%. OTC has the advantage of restoring natural fertility and presents a LBR of 33%, compared with the LBR of 19% among 266 IVF patients. In addition, OTC has the benefit of restoring the endocrine function. It has been observed that the shortest recovery time of the first menstruation after transplantation was 3.9 months, and the recovery rate of ovarian function reached 100%. To date, a growing number of cancer survivors and patients with other diseases are benefiting from fertility preservation measures. In the face of declining human fertility, fertility preservation provides a new approach to human reproduction. Fertility preservation should be applied in line with the ethical principles so as to fully protect the rights and interests of patients and their offsprings.

Infertility affects an estimated 10 to 15 percent of couples worldwide, with approximately half of the cases attributed to male-related issues. Most men diagnosed with infertility exhibit symptoms such as oligospermia, asthenospermia, azoospermia, and compromised sperm quality. Spermatogenesis is a complex and tightly coordinated process of germ cell differentiation, precisely regulated at transcriptional, posttranscriptional, and translational levels to ensure stage-specific gene expression during the development of spermatogenic cells and normal spermiogenesis. N6-methyladenosine (m6A) stands out as the most prevalent modification on eukaryotic mRNA, playing pivotal roles in various biological processes, including mRNA splicing, transportation, and translation. RNA methylation modification is a dynamic and reversible process primarily mediated by \"writers\", removed by \"erasers\", and recognized by \"readers\". In mammals, the aberrant methylation modification of m6A on mRNA is associated with a variety of diseases, including male infertility. However, the precise involvement of disrupted m6A modification in the pathogenesis of human male infertility remains unresolved. Intriguingly, a significant correlation has been found between the expression levels of m6A regulators in the testis and the severity of sperm concentration, motility, and morphology. Aberrant expression patterns of m6A regulatory proteins have been detected in anomalous human semen samples, including those of oligospermia, asthenozoospermia, and azoospermia. Furthermore, the examination of both sperm samples and testicular tissues revealed abnormal mRNA m6A modification, leading to reduced sperm motility and concentration in infertile men. Consequently, it is hypothesized that dysregulation of m6A modification might serve as an integral link in the mechanism of male infertility. This paper presents a comprehensive review of the recent discoveries regarding the spatial and temporal expression dynamics of m6A regulators in testicular tissues and the correlation between deregulated m6A regulators and human male infertility. Previous studies predominantly utilized constitutive or conditional knockout animal models for testicular phenotypic investigations. However, gene suppression in additional tissues could potentially influence the testis in constitutive knockout models. Furthermore, considering the compromised spermatogenesis observed in constitutive animals, distinguishing between the indirect effects of gene depletion on testicular development and its direct impact on the spermatogenic process is challenging, due to their intricate relationship. Such confounding factors might compromise the validity of the findings. To address this challenge, an inducible and conditional gene knockout model may serve as a superior approach. To date, nearly all reported studies have concentrated solely on the level changes of m6A and its regulators in germs cells, while the understanding of the function of m6A modification in testicular somatic cells remains limited. Testicular somatic cells, including peritubular myoid cells, Sertoli cells, and Leydig cells, play indispensable roles during spermatogenesis. Hence, comprehensive exploration of m6A modification within these cells as an additional crucial regulatory mechanism is warranted. In addition, exploration into the presence of unique methylation mechanisms or m6A regulatory factors within the testes is warranted. To elucidate the role of m6A modification in germ cells and testicular somatic cells, detailed experimental strategies need to be implemented. Among them, manipulation of the levels of key enzymes involved in m6A methylation and demethylation might be the most effective approach. Moreover, comprehensive analysis of the gene expression profiles involved in various signaling pathways, such as Wnt/β-catenin, Ras/MAPK, and Hippo, in m6A-modified germ cells and testicular somatic cells can provide more insight into its regulatory role in the spermatogenesis process. Further research in this area could provide valuable insights for developing innovative strategies to treat male infertility. Finally, considering the mitigation impact of m6A imbalance regulation on disease, investigation concerning whether restoring the equilibrium of m6A modification regulation can restore normal spermatogenesis function is essential, potentially elucidating the pivotal clinical significance of m6A modulation in male infertility.

The Temminck\'s pangolin (Smutsia temminckii) is one of eight pangolin species worldwide and the only pangolin present in southern Africa. Historically, pangolins have not been able to reproduce successfully in captivity and this may be in part due to the lack of knowledge and understanding with regards to the pangolin reproductive system (anatomy, physiology, biology) in all eight species. This original study describes the gross anatomy of the male Temminck\'s pangolin from three adult individuals investigated. The male Temminck\'s pangolin presented a short, conical penis with ascrotal (internal) testes, similar to many other myrmecophagous mammals such as the aardvark (Orycteropus sp.) and anteaters (suborder: Vermilingua). However, the orientation of the penis of the Temminck\'s pangolin differed in that it was oriented cranioventrally, in contrast to the caudal orientation of the giant anteater. The testes were found to be bilaterally flattened with an elongate oval shape, similar to the aardvark. The specific characteristics of the reproductive tract of the male Temminck\'s pangolins are thought to be adaptations to their peculiar lifestyle as the male portrays characteristics that indicate adaptation to a lower basal metabolic rate and body temperature as well as to their defensive mechanism of rolling up into a ball. Our study suggests the male Temminck\'s pangolin reproductive anatomy is most similar and comparable to the Xenarthrans and the aardvark that display the same fossorial activities as pangolins, and the male morphology is not comparable to the phylogenetically closely-related Carnivora.

3-chloro-1,2-propanediol (3-MCPD) is a newly discovered food process pollutant with nephrotoxicity. And the mechanism by which 3-MCPD affects male spermatogenesis has not been fully studied. Cell viability, blood-testis barrier (BTB) related protein, progesterone content, reactive oxygen species (ROS) generation, and cell apoptosis were determined by a CCK8 assay, western blot, ELISA, flow cytometry, and TUNEL staining, respectively. Wistar rats were divided into three groups: low-dose 3-MCPD, high-dose 3-MCPD, and control. Sperm parameters, hormonal levels, and biomarkers of oxidative stress in the testis and epididymis were detected by ELISA. Multiple molecular experiments including molecular docking and western blot were used to elucidate the underlying mechanisms. 3-MCPD affects testicular cell activity, and promotes ROS production and apoptosis. Disrupting the integrity of BTB in the body, downregulating sex hormones and sperm quality, and promoting apoptosis. 3-MCPD may function through CYP2C9. This study preliminarily explores the mechanism by which 3-MCPD affects spermatogenesis. It was found that 3-MCPD destroys the structure and function of BTB and damages the testicular function of male mice, thus affecting the process of spermatogenesis via CYP2C9.

Notch is a conserved cell-signaling pathway involved in spermatogenesis regulation. This study firstly evaluated the presence, localization patterns, acquisition origin and relation to acrosome reaction of Notch proteins in bull sperm. Western Blot analysis detected all Notch proteins in ejaculated bull sperm, and immunostaining described their specific sperm localization. Recovery of sperm from different segments showed that Notch proteins have testicular origin (NOTCH1, NOTCH2, DLL4), are sequentially acquired during sperm maturation along epididymal transit (NOTCH3, DLL3, JAGGED1-2), or post-ejaculation (DLL1, NOTCH4). Testis NOTCH2 is ubiquitously expressed in all germ-cell lines, whereas DLL4 is expressed in round and elongated spermatids during the Golgi, Cap, Acrosome and Maturation phases. In vitro spontaneous and induced sperm acrosome reaction induce consistent sperm regional relocation of NOTCH2, DLL4 and JAGGED1, and these relocation patterns are significantly associated to sperm acrosome status. NOTCH2 and JAGGED1 are relocated from the head apical to the post-equatorial regions, whereas DLL4 is lost along with the acrosome, evidencing that sperm spatial redistribution of NOTCH2 and JAGGED1 is linked to acrosome reaction onset, whereas DLL4 loss is linked to AR completion. Overall, results prompt for a relevant Notch role in bull sperm acrosome testicular development, epididymal maturation and acrosome reaction.

A Wt1 conditional deletion, nuclear red fluorescent protein (RFP) reporter allele was generated in the mouse by gene targeting in embryonic stem cells. Upon Cre-mediated recombination, a deletion allele is generated that expresses RFP in a Wt1-specific pattern. RFP expression was detected in embryonic and adult tissues known to express Wt1, including the kidney, mesonephros, and testis. In addition, RFP expression and WT1 co-localization was detected in the adult uterine stroma and myometrium, suggesting a role in uterine function. Crosses with Wnt7a-Cre transgenic mice that express Cre in the Müllerian duct epithelium activate Wt1-directed RFP expression in the epithelium of the oviduct but not the stroma and myometrium of the uterus. This new mouse strain should be a useful resource for studies of Wt1 function and marking Wt1-expressing cells.

Exposure to the neonicotinoid insecticide, imidacloprid (IMI), causes reproductive toxicity in mammals and reptiles. However, reports on the effects of IMI on the gonads in birds are grossly lacking. Therefore, this study investigated the effects of pubertal exposure to IMI on the histology, ultrastructure, as well as the cytoskeletal proteins, desmin, smooth muscle actin and vimentin, of the gonads of Japanese quail (Coturnix coturnix japonica). Quails were randomly divided into four groups at 5 weeks of age. The control group was given only distilled water, whereas, the other three experimental groups, IMI was administered by oral gavage at 1.55, 3.1, and 6.2 mg/kg, twice per week for 4 weeks. Exposure to IMI doses of 3.1 and 6.2 mg/kg caused dose-dependent histopathological changes in the ovary and testis. In the ovary, accumulation of lymphocytes, degenerative changes, and necrosis with granulocyte infiltrations were observed, while in the testis, distorted seminiferous tubules, germ cell sloughing, vacuolisations, apoptotic bodies, autophagosomes, and mitochondrial damage were detected. These changes were accompanied by a decreased number of primary follicles (P ≤ 0.05) in the ovary and a decrease (P ≤ 0.05) in the epithelial height, luminal, and tubular diameters of seminiferous tubules at the two higher dosages. In addition, IMI had a negative effect on the immunostaining intensity of desmin, smooth muscle actin, and vimentin in the ovarian and testicular tissue. In conclusion, exposure to IMI during puberty can lead to a range of histopathological alterations in the gonads of Japanese quails, which may ultimately result in infertility.

OBJECTIVE: To assess the role of 3.0 T Diffusion Tensor Imaging (DTI) and Fiber Tractography (FT) of the testes in the work-up of nonobstructive azoospermia (NOA).
METHODS: This prospective study included consecutive NOA men and controls. A 3.0 T scrotal MRI was performed, including DTI. The testicular apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were calculated. FT reconstructions were created. The Kruskal-Wallis test, followed by pairwise comparisons, assessed differences in testicular ADC and FA between NOA histologic phenotypes (group 1: hypospermatogenesis; group 2: maturation arrest; and group 3: Sertoli cell-only syndrome) and normal testes. The Mann-Whitney-U test compared ADC and FA between NOA testes with positive and negative sperm retrieval. Visual assessment of the testicular fiber tracts was performed. Fiber tracts fewer in number, of reduced thickness, disrupted and/or disorganized were considered \"abnormal\". Chi-square tests and binary logistic regression analysis assessed variations in testicular fiber tracts morphology.
RESULTS: Twenty-nine NOA men (mean age: 39 ± 5.93 years) and 20 controls (mean age: 26 ± 5.83 years) were included for analysis. Higher ADC (p < 0.001) and FA (p < 0.001) was observed in NOA testes compared to controls. Differences in FA were found between groups 1 and 3 (0.07 vs 0.10, p = 0.26) and groups 2 and 3 (0.07 vs 0.10, p = 0.03), but not between groups 1 and 2 (p = 0.66). An increase in FA was observed in NOA testes with Sertoli cell-only syndrome compared to hypospermatogenesis and maturation arrest. FA was higher in NOA testes with negative results for the presence of sperm compared to those with positive results (0.09 vs 0.07, p = 0.006). FT showed \"abnormal\" fiber tracts in NOA testes (p < 0.001).
CONCLUSIONS: 3.0 T DTI and FT provide an insight into deranged spermatogenesis in NOA testes.

BACKGROUND: Apricot kernels containing amygdalin (AMG) as the major cyanogenic glycoside are potentially useful as a complementary therapy for the management of several ailments including cancer. Nevertheless, little is known regarding the toxic and therapeutic doses of AMG, particularly in terms of male reproduction. Hence, this study evaluates selected qualitative characteristics of rabbit testicular tissue following in vivo administration of AMG or apricot kernels for 28 days.
METHODS: The rabbits were randomly divided into five groups (Control, P1, P2, P3, P4). The Control received no AMG/apricot kernels while the experimental groups P1 and P2 received a daily intramuscular injection of amygdalin at a dose of 0.6 and 3.0 mg/kg of body weight (b.w.) for 28 days, respectively. P3 and P4 received a daily dose of 60 and 300 mg/kg b.w. of crushed apricot kernels mixed with feed for 28 days, respectively. Changes to the testicular structure were quantified morphometrically, while tissue lysates were subjected to the evaluation of reactive oxygen species (ROS) production, total antioxidant capacity, activities of antioxidant enzymes, and glutathione concentration. The extent of damage to the proteins and lipids was quantified as well. Levels of selected cytokines were determined by the enzyme-linked immunosorbent assay while a luminometric approach was used to assess the activity of caspases.
RESULTS: Rabbits treated with 3.0 mg/kg b.w. AMG presented a significantly increased protein oxidation (p = 0.0118) accompanied by a depletion of superoxide dismutase (p = 0.0464), catalase (p = 0.0317), and glutathione peroxidase (p = 0.0002). Significantly increased levels of interleukin-1 beta (p = 0.0012), tumor necrosis factors alpha (p = 0.0159), caspase-3/7 (p = 0.0014), and caspase-9 (p = 0.0243) were also recorded in the experimental group P2 when compared to the Control. No effects were observed in the rabbits treated with apricot kernels at the oxidative, inflammatory, and histopathological levels.
CONCLUSIONS: Apricot kernels did not induce toxicity in the testicular tissues of male rabbits, unlike pure AMG, which had a negative effect on male reproductive structures carried out through oxidative, inflammatory, and pro-apoptotic mechanisms.

Organoid systems have revolutionised various facets of biological research by offering a three-dimensional (3D), physiologically relevant in vitro model to study complex organ systems. Over recent years, testicular organoids have been publicised as promising platforms for reproductive studies, disease modelling, drug screening, and fertility preservation. However, the full potential of these systems has yet to be realised due to inherent limitations. This paper offers a comprehensive analysis of the current challenges associated with testicular organoid models. Firstly, we address the inability of current organoid systems to fully replicate the intricate spatial organisation and cellular diversity of the in vivo testis. Secondly, we scrutinise the fidelity of germ cell maturation within the organoids, highlighting incomplete spermatogenesis and epigenetic inconsistencies. Thirdly, we consider the technical challenges faced during organoid culture, including nutrient diffusion limits, lack of vasculature, and the need for specialised growth factors. Finally, we discuss the ethical considerations surrounding the use of organoids for human reproduction research. Addressing these limitations in combination with integrating complementary approaches, will be essential if we are to advance our understanding of testicular biology and develop novel strategies for addressing reproductive health issues in males.