Neonatal testicular germ cells/gonocytes, transform into stem cells for spermatogenesis during ‘minipuberty’ (3-6 months old), drive change in the timing of ochidopexy. This study aimed to examine the timing of gonocyte transformation of cryptorchid testes ≤18 months of age with unilateral and bilateral UDT, and in patients with complete androgen insensitivity syndrome (CAIS) and partial androgen insensitivity syndrome (PAIS).
Material and methods
Testicular biopsies (42) from 35 patients with unilateral and bilateral UDT, and PAIS/CAIS aged 10 days-18 months were used for immunohistochemistry with antibodies (Oct4, Ki67, Sox9 and C-Kit) followed by confocal imaging, cell accounting and statistical analysis.
Both Number of Sertoli cells/tubule and germ cell (GC)/tubule decreased with age, and % empty tubules (no GC) increased with age but with no significant differences between patient groups. Oct4+ germ cells/tubule decreased with age and disappeared after 12 month of age. There were Oct4+ GC in unilateral and CAIS UDT ≤12 month old, but no Oct4+ GCs were observed when the age reached 9 months old in bilateral UDT, except one 9 month old patient with bilateral UDT ) that showed persisting gonocytes in a testicular tubule with Oct4+/Ki67+/C-kit+ germ cells clustered at the centre of the tubule. There were a few GCs and Sertoli cells proliferating (Ki67+) during the first year and very few afterwards. Most proliferating Oct4+ germ cells (Oct4+/Ki67+) were located off the tubular basement membrane.
Our study showed that expression of Oct4, the gonocyte marker, gradually decreased after minipuberty and transformation into spermatogonia. Germ cells and Sertoli cells do undergo mitosis during the first 12 months although not abundantly. We propose that Oct4+ gonocytes transformation into spermatogonia via proliferation and migration to the basement membrane may be delayed in UDT.