Comparison of the Intratesticular and the Intratubular Injection
First, we compared the two types of injection methods with respect to the transgene expression efficiency in sper-matogenic cells. Intratesticular injection is an injection of plasmid DNA into the interstitial space of the testis as described by Muramatsu et al.. Intratubular injection is a DNA injection into the seminiferous tubules. CMV-lacZ was injected into mice (4 wk old) using each method, and the p-gal expression patterns were compared 2 days later As shown in Figure 1A, an intratesticular injection resulted in weak p-gal expression throughout the entire testis, in which the interstitium as well as the seminiferous tubules were extensively stained (Fig. 1C). birth control yasmin
In contrast, an intratubular injection resulted in strong p-gal expression along the seminiferous tubules (Fig. 1B), in which strong expression was observed in various stages of the spermatogenic cells and Sertoli cells in the seminiferous tubule, whereas positive cells were only slightly detected in the interstitial space outside the seminiferous tubules (Fig. 1D). These results indicated that the intratubular injection method was more suitable for gene transfer to spermatogenic germ cells as the target cells. Therefore, intratubular injection was used to inject DNA into the seminiferous tubules in subsequent experiments.
FIG. 1. Expression of the CMV-lacZ transgene 48 h after gene transfer with two different injection methods. The half-cut testes were X-gal-stained (A, B, bar = 1 mm), and then 15-^m sections were cut (C, D, bar = 100 ^m). A) Testis treated with intratesticular DNA injection. B) Testis treated with intratubular DNA injection. Strong expression of p-gal is detected along the seminiferous tubules. C) Cross section of A. The interstitium is also stained (indicated by arrowheads). D) Cross section of B. p-gal-positive cells reside only within the seminiferous tubules.