Quantitative (stereological) study of incomplete spermatogenic suppression induced by testosterone undecanoate injection in rats.
OBJECTIVE
To evaluate the key lesions in spermatogenesis suppressed partially by testosterone undecanoate (TU) treatment.


METHODS
Adult male SD rats were treated with vehicle or TU (19 mg/kg) injection (i.m.) every 15 days for 130 days. The numbers of all types of cells (nuclei) in the seminiferous tubules and the interstitial tissue were estimated using a contemporary stereological tool, the optical disector.


RESULTS
In response to TU treatment, the numbers of non-type B spermatogonia, type B spermatogonia and late elongated spermatids per testis were reduced to 51 %, 66 % and 14 % of the controls, respectively. The conversion ratios from type B spermatogonia to early spermatocytes and pachytene spermatocytes were not significantly affected and the ratios to the later germ cell types fell to 51 % - 65 % of the controls. Less than 1.0 % of immature round spermatids were seen sloughing into the tubule lumen, 4.0 % of elongated spermatids retained in the seminiferous epithelium, and about half of the elongated spermatid nuclei appreciably malformed. Leydig cells were atrophied but their number and the peritubular myoid cell number per testis were unchanged.


CONCLUSIONS
Double inhibition of spermatogenesis (i.e. inhibition at spermiation and spermatogonial conversion to type B spermatogonia), a scenario seen in the monkey and human following gonadotrophin withdrawal, was not sufficiently effective for a complete spermatogenic suppression in the rat after TU treatment, probably due to ineffective inhibition of the Leydig cell population and therefore the intra-testicular testosterone levels.
Yang
Zheng-Wei
ZW
Morphometric Research Laboratory, North Sichuan Medical College, Nanchong, Sichuan 637007. zwyang@mail.nctele.com.
Guo
Yang
Y
Lin
Li
L
Wang
Xing-Hai
XH
Tong
Jian-Sun
JS
Zhang
Gui-Yuan
GY
D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000648:ultrastructure; D003864:Depression, Chemical; D007985:Leydig Cells / Q000187:drug effects; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012708:Sertoli Cells / Q000187:drug effects; D013076:Sperm Count; D013087:Spermatids / Q000187:drug effects; D013091:Spermatogenesis / Q000187:drug effects*; D013739:Testosterone / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology*
D013739:Testosterone; C010792:testosterone undecanoate