**3.1 Spatial resolution**

Besides the lack of an excitation coil, one of the main advantages of wire-core fluxgates is the diameter of the wire, usually very narrow (several tens of µm). A narrow diameter is advantageous not only for miniaturization, but also for improvement of spatial resolution in magnetic field measurement. Let us consider, for instance, a magnetic field HZ with constant gradient along the x direction, as shown in Fig. 5. Parallel fluxgates must use either a ring or a racetrack core to reduce the demagnetizing factor and compensate voltage peaks for zero measured fields. Such core has two sensitive sections in the measurement direction (namely A and B in Fig.5, left) which sense different fields HZA and HZB. The total field measured by the parallel fluxgate will be the average of HZA and HZB.

Parallel fluxgates rarely have a core narrower than 1÷2 cm, limiting the spatial resolution to such level. On the contrary, orthogonal fluxgates have the sensitive cross section of a single wire making it possible to measure the magnetic field HZ in the single spot, with resolution limited by the diameter. Since typical wires used for orthogonal fluxgates have diameters up to 100 µm, the spatial resolution of orthogonal fluxgates is two orders of magnitude better than conventional parallel fluxgates. To this extent, they were successfully employed for applications such as magnetic imaging. For instance, in (Terashima & Sasada, 2002) a gradiometer based on a wire-core orthogonal flux is presented. The gradiometer is used to measure magnetic fields emerging from a specimen of 3% grain oriented silicon steel, with steps of 50 µm (the diameter of the amorphous wire used as a core is 120 µm). Since the spatial resolution of the sensor is very high it was possible to measure the magnetic field emerging from a single domain, and then graphically represent the domain's topology of the sample.

Parallel fluxgates, based on PCB technology, with an ultra thin core (50 µm) have also been proposed (Kubik et al., 2007). In this case, the spatial resolution is remarkably improved in y direction, but it is still poor in the x direction.

Fig. 5. Spatial resolution in parallel (left) and orthogonal fluxgates (right).


*3.1.1 Biochips*

As a product of the physical and biological sciences, biochips provide molecular analysis with high efficiency. Especially in gene engineering, biology, and medicine, biochips that do wonders in early diagnosis of diseases also enable gene sequencing, pharmacology and toxicology, analysis of DNA/RNA strands, and accurate identification of proteins. The most current studies are the determination of gene expression between human cells and tissue. In this way, global gene expression analysis is highly illuminating in the early detection of tumors in the living body. Application areas of biochips can be listed as a diagnostic tool in clinical medicine, quantifying

**Figure 8.** *The nanorobotics.*


**2. EDCs induce reproductive system toxicity: ultrastructural, cellular and molecular changes**

The male reproductive system is composed by two testes, a system of genital ducts, the accessory glands (seminal vesicles, prostate, Cowper and Littre glands) and the penis [15].  This localization maintains the temperature at 2–4°C lower than the body temperature, optimal for the testes function. Testes are surrounded by two different layers of protective tissue, the *tunica albuginea* and the *tunica vaginalis*. The testicular parenchyma is composed of one to three seminiferous tubules, the functional unit of the testis, and of interstitial tissue surrounding the tubules that contain the Leydig cells (LC), which are responsible for the production of T in the presence of luteinizing hormone (LH) (**Figure 1**) [16]. The seminiferous tubules are composed of male germ cells (spermatogonia, spermatocytes and spermatids) and Sertoli cells (SC). SC are involved in the mechanical support and nutrition of germ cells, regulation of male germ cell proliferation and differentiation, phagocytosis, steroid hormone synthesis and metabolism and maintenance of the integrity of seminiferous epithelium. The male reproductive system is responsible for the production of spermatozoa, for the synthesis and secretion of male sex hormones and for the delivery of male gametes into the female reproductive tract. The process of spermatogenesis is highly regulated by the hypothalamic-pituitary-gonadal (HPG) axis.

Evidences suggest that the normal morphology and function of the male reproductive system are affected by several factors including environmental pollutants (**Figure 1**) (e.g., EDCs). In addition to altered testicular morphology and dysfunction, exposure to EDCs also increased the incidence of testicular pathologies. For instance, exposure to phthalates was associated with the development of testicular cancer, cryptorchidism and hypospadias [17]. This section discusses the current knowledge on reproductive system EDC toxicity in humans and other animals.

**23**

**Figure 1.**

*The Role of Endocrine-Disrupting Chemicals in Male Fertility Decline*

**2.1 Changes in volume/weight of reproductive organs**

*Schematic representation of the effects of EDCs on HPG axis and testicular morphology.*

The volume/weight of the male reproductive organs is an important indicator of the integrity of this system. Several animal studies showed a significant decrease in the weight of the testes and sex accessory tissues in animals exposed to EDCs [4, 18–23]. For instance, male rats treated with 10 and 20 mg/(kg day) of TCS revealed a significant decrease in the weight of the testes, epididymis, ventral prostate, vas deferens and seminal vesicles [18]. However, an administration of 5 mg/(kg day) of TCS did not cause significant change in the testes and sex accessory tissues [18]. Recently, Lan et al. [4] showed that the absolute

*DOI: http://dx.doi.org/10.5772/intechopen.88330*

*The Role of Endocrine-Disrupting Chemicals in Male Fertility Decline DOI: http://dx.doi.org/10.5772/intechopen.88330*

*Male Reproductive Health*

male subfertility or infertility status.

**and molecular changes**

the hypothalamic-pituitary-gonadal (HPG) axis.

tive health.

effects on human health and are contributing to the trends in occurrence of male reproductive health problems and the decline in male fertility [3]. According to the literature, male reproductive decline may result from a combination of morphological, functional and molecular alterations in the reproductive organs, often due to exposure to EDCs. Most studies are focused either on the evaluation of basic seminal parameters or reproductive outcomes, but there are evidences that EDCs may impact at the level of the reproductive and endocrine systems. For example, there are evidences that TCS has a tendency to bioaccumulate in the epididymis [4]. Bisphenol A (BPA) has been reported to have both estrogenic and antiandrogenic effects [5–7]. It has been also negatively associated with sperm quality [8–10]. Toxicological studies showed that BPA caused adverse reproductive outcomes, namely, decreased epididymal weight, daily sperm production and testosterone (T) levels in rodents [11–13]. Recently, our group performed a systematic review regarding the effect of exposure to mercury (Hg) on human fertility [14]. Results revealed that higher levels of Hg in blood and hair were associated with

This chapter summarizes the effects of male exposure to EDCs on markers of male fertility. The agents discussed here, which include TCS, BPA, metals (such as cadmium (Cd) and Hg), polychlorinated biphenyls (PCBs) and others were chosen based on their human exposure prevalence and adverse effects on human reproduc-

**2. EDCs induce reproductive system toxicity: ultrastructural, cellular**

The male reproductive system is composed by two testes, a system of genital ducts, the accessory glands (seminal vesicles, prostate, Cowper and Littre glands) and the penis [15].  This localization maintains the temperature at 2–4°C lower than the body temperature, optimal for the testes function. Testes are surrounded by two different layers of protective tissue, the *tunica albuginea* and the *tunica vaginalis*. The testicular parenchyma is composed of one to three seminiferous tubules, the functional unit of the testis, and of interstitial tissue surrounding the tubules that contain the Leydig cells (LC), which are responsible for the production of T in the presence of luteinizing hormone (LH) (**Figure 1**) [16]. The seminiferous tubules are composed of male germ cells (spermatogonia, spermatocytes and spermatids) and Sertoli cells (SC). SC are involved in the mechanical support and nutrition of germ cells, regulation of male germ cell proliferation and differentiation, phagocytosis, steroid hormone synthesis and metabolism and maintenance of the integrity of seminiferous epithelium. The male reproductive system is responsible for the production of spermatozoa, for the synthesis and secretion of male sex hormones and for the delivery of male gametes into the female reproductive tract. The process of spermatogenesis is highly regulated by

Evidences suggest that the normal morphology and function of the male reproductive system are affected by several factors including environmental pollutants (**Figure 1**) (e.g., EDCs). In addition to altered testicular morphology and dysfunction, exposure to EDCs also increased the incidence of testicular pathologies. For instance, exposure to phthalates was associated with the development of testicular cancer, cryptorchidism and hypospadias [17]. This section discusses the current knowledge on reproductive system EDC toxicity in

**22**

humans and other animals.

**Figure 1.** *Schematic representation of the effects of EDCs on HPG axis and testicular morphology.*