In normal seminiferous tubules (Fig. 30.1a, b), albumin immunoreactivity was mainly detected around peritubular myoid cells, forming continuous immunostaining areas as well as among interstitial Leydig cells and inside blood capillaries . Another albumin immunostaining was detected as small archlike patterns within the seminiferous epithelium and restricted in the basal compartment , locating around some spermatogonia (arrows in Fig. 30.1b). Appearance and disappearance of the archlike patterns were closely related to the developmental stages of seminiferous epithelial cycles. The number of the archlike patterns at stages VII–VIII of the seminiferous epithelial cycle (mature spermatozoon accumulated at the upper luminal part and ready to release) was much higher than that at stages I–II (spermatogenesis proceeding to the early spermatid).

The cadmium chloride (CdCl₂) was intraperitoneally injected at a single dose to induce their testis damage, as previously described [2]. Thereafter, the mice were examined 24 and 48 h after the Cd treatment. In 24 h (Fig. 30.1c, d), the albumin immunostaining was detected not only in the basal compartment of seminiferous epithelium but also in the adluminal compartment between supporting Sertoli cell s and developing spermatogenic cells (Fig. 30.1d), indicating abnormal immunoreactivity of serum albumin through BTB structures. Forty-eight hours after the Cd treatment, some seminiferous tubules were shown to be typical atrophic structures, by decreasing the number of germ cells. In such seminiferous tubules, the albumin immunostaining was also detected between the Sertoli cells.

The present findings confirmed that the immunointensity of leaked albumin through BTB in the basal compartment s was obviously stronger in the seminiferous epithelium of the living mice at 24 h after the Cd treatment. The different immunolocalizations of serum albumin in the seminiferous tubules between normal and Cd-treated mouse testis organs support an idea that the TJ structure against protein permeability between Sertoli cell s is the most vulnerable portion affected by Cd toxicity, as reported before [10, 16].

The time-dependent morphological changes of seminiferous tubules in the Cd-treated living mice, including different immunostaining patterns of albumin in the basal compartment with BTB disruption, can be clearly detected by the “in vivo cryotechnique ” combined with both freeze-substitution and immunohistochemistry .