F4/80-positive cells rapidly accumulate around tubuli recti and rete testis between 3 and 4 weeks of age in the mouse: an immunohistochemical study.

Problem: Previous studies demonstrated that F4/80 antigen (murine macrophage-specific antigen)-positive cells in testes of normal adult mice accumulate particularly in the interstitium adjacent to the tubuli recti and rete testis (i.e., the central region). However, it remains unknown whether this accumulation is a congenital or acquired phenomenon.
Method of Study: The distribution of F4/80-positive cells on frozen sections of testes obtained from various aged mice was immunohistochemically examined to determine when the positive cells specifically accumulate in the central region.
Results: F4/80-positive cells were homogeneously distributed throughout the testicular interstitium with no specific accumulation until 2 weeks of age. However, at 3 weeks of age, the density of positive cells in the central region became slightly, but significantly, higher than that in the interstitium between the seminiferous tubules. Between 3 and 4 weeks of age, the cell density in the central region increased rapidly, the density at 4 weeks of age reaching the level of the mature testes of 8-week-old mice.
Conclusion: These results demonstrate that the specific accumulation of F4/80-positive cells in the central region is an acquired phenomenon, which starts and ends before puberty.