Testicular histomorphometry and the proliferative and apoptotic activities of the seminiferous epithelium in Syrian hamster (Mesocricetus auratus) during regression owing to short photoperiod.
During the non-breeding season some animals exhibit testicular atrophy, decreased testicular weight and reduced seminiferous tubule diameter accompanied by depletion of the seminiferous epithelium. Some cellular factors involved in this depletion are changes in germ cell proliferation and apoptosis. In the Syrian hamster this depletion has been studied histologically and in terms of the involvement of proliferation and apoptosis in the seminiferous epithelium of fully regressed testes. The objectives of this study included the histomorphometrical characterization of the testis and the determination of the proliferative and apoptotic activity of germ cells in the seminiferous epithelium during testicular regression owing to short photoperiod. The study was performed using conventional light microscopy (hematoxylin and eosin), proliferating cell nuclear antigen and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP in situ nick end labelling staining, image analysis software, and transmission electron microscopy in three established regression groups: mild regression (MR), strong regression (SR), and total regression (TR). Morphometrically a gradual decrease in total tubular area and in the testicular, tubular, and epithelial volumes was observed during testicular regression. Interstitial and luminal volumes decreased from the MR group onwards. The tubular length decreased from MR to SR. As regards spermatogonial proliferation, only an initial decrease in proliferative activity was observed, whereas apoptotic germ cell activity increased throughout regression. The number of germ cells studied decreased throughout the process of testicular regression. In conclusion, testicular regression in Syrian hamster comprises two histomorphometrical phases, the first involving a decrease in seminiferous tubular diameter and volume and the second involving shortening of the seminiferous tubule and a decrease in interstitial volume. At the cellular level, there is an initial decrease in proliferation and increase in apoptosis involving all germ cells. At the end of regression, the proliferative and apoptotic activities of the spermatogonia recover the values observed prior to regression in preparation for recrudescence.
Department of Cell Biology and Histology, Medical School, IMIB-Arrixaca, Regional Campus of International Excellence Campus Mare Nostrum, University of Murcia, Murcia, Spain.
V
V
Seco-Rovira
Department of Cell Biology and Histology, Medical School, IMIB-Arrixaca, Regional Campus of International Excellence Campus Mare Nostrum, University of Murcia, Murcia, Spain.
E
E
Beltrán-Frutos
Department of Cell Biology and Histology, Medical School, IMIB-Arrixaca, Regional Campus of International Excellence Campus Mare Nostrum, University of Murcia, Murcia, Spain.
C
C
Ferrer
Department of Cell Biology and Histology UFI 11/44, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, Leioa, Spain.
F J
FJ
Saez
Department of Cell Biology and Histology, Medical School, IMIB-Arrixaca, Regional Campus of International Excellence Campus Mare Nostrum, University of Murcia, Murcia, Spain.
J F
JF
Madrid
Department of Statistics, Medical School, University of Murcia, Murcia, Spain.
M
M
Canteras
Department of Cell Biology and Histology, Medical School, IMIB-Arrixaca, Regional Campus of International Excellence Campus Mare Nostrum, University of Murcia, Murcia, Spain.
L M
LM
Pastor
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001284:Atrophy; D049109:Cell Proliferation; D006224:Cricetinae; D020287:In Situ Nick-End Labeling; D008297:Male; D008647:Mesocricetus; D046529:Microscopy, Electron, Transmission; D017440:Photoperiod; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D012670:Seminiferous Epithelium / Q000166:cytology / Q000473:pathology*; D013091:Spermatogenesis / Q000502:physiology; D013093:Spermatogonia / Q000166:cytology; D013194:Staining and Labeling; D013737:Testis / Q000033:anatomy & histology / Q000166:cytology / Q000473:pathology*
D018809:Proliferating Cell Nuclear Antigen
apoptosis; hamster; photoperiod; proliferation; seasonal reproduction; testes