Inverse relationship between testicular proliferation and apoptosis in mammalian seasonal breeders

Blöttner, S.; Hingst, O.; Meyer, Heinrich

doi:10.1016/0093-691x(95)00187-d

Cited by 48 publications

(38 citation statements)

References 11 publications

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“…The observed maximum numbers of apoptotic cells during activated spermatogenesis (June and August) in roe deer are not completely consistent with results from an earlier study in which a general inverse correlation between apoptosis and proliferation has been postulated, inclusive of increased apoptosis during testis regression ; however, Blottner et al (1995) employed only one method (ELISA) for the evaluation of apoptosis, the complete annual cycle was not assessed for this parameter and only a few measurements from the non-breeding season were included. This may explain differences in the outcome of the two studies.…”

Section: Discussioncontrasting

confidence: 55%

Apoptosis is not the cause of seasonal testicular involution in roe deer

Blöttner

Schön²,

Roelants

2006

Cell Tissue Res

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Apoptosis is involved in the regulation of spermatogenesis. The involution of testes in seasonal breeders might be expected to involve enhanced apoptotic cell elimination. We have compared seasonally changing testicular apoptosis in roe deer with that in non-seasonally breeding cattle. Apoptotic cells were detected as TUNEL-positive cells by both flow-cytometric analysis and in situ localisation of fragmented DNA in tissue sections. Apoptosis-induced DNA fragments were also assessed by enzyme-linked immunosorbent assay (ELISA) in homogenised testicular parenchyma. As expected, the testis mass and the percentage of haploid cells in roe deer showed a seasonal pattern with a significant maximum during the rut (August), whereas no annual variation of these parameters was found in bulls. All three methods for determining apoptosis showed similar findings. Roe deer exhibited significant seasonal fluctuation of total apoptotic activity (ELISA, apoptotic cells per tubule cross section) with a maximum during the breeding season. However, the seasonal differences in the number of apoptotic cells corresponded to the variable total numbers of spermatogonia and spermatocytes per tubule cross section. Thus, the percentages of TUNEL-positive cells related to the combined number of both germ cell types showed no seasonal variance, as confirmed by percentages of apoptotic cells analysed flow-cytometrically. The maximum level of apoptosis during the rut in roe deer was similar to the values obtained during the invariably high spermatogenic activity in cattle. These results suggest that, in roe deer, apoptosis is not the cause of the seasonal involution of testes.

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Section: Discussioncontrasting

confidence: 55%

Apoptosis is not the cause of seasonal testicular involution in roe deer

Blöttner

Schön²,

Roelants

2006

Cell Tissue Res

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“…In some species, for example, Brown Hare and Roe deer, where apoptosis and proliferation have been seen to be related, it has been observed that during the non-reproductive, in addition to an increase in apoptosis, there is a reduction in the proliferation of germ cells (Blottner et al, 1995;Strbenc et al, 2003). Although in both species this phenomenon is well-known, the Roe Deer has been considered as a species where germ cell apoptosis is not the main mechanism responsible for epithelial atrophy, whereas in Brown Hare apoptosis plays a critical role in such atrophy.…”

Section: Discussionmentioning

confidence: 99%

“…This decrease is significant between SR and TR, coinciding with the recovery of the proliferative index. In semiquantitative studies about the proliferation of germ cells in seasonally breeding animals which undergo, as hamster, a strong involution of spermatogenesis, for example, Brown Hare (Strbenc et al, 2003), Roe Deer (Blottner et al, 1995) or the Iberian Mole (Dadhich et al, 2010), an increase in the proliferative activity of spermatogonia preceding the breeding season period has been observed. In contrast, in the Syrian hamster there is some controversy about whether there is a higher or lower spermatogonia PI in fully regressed testes.…”

Section: Discussionmentioning

confidence: 99%

Testicular histomorphometry and the proliferative and apoptotic activities of the seminiferous epithelium in Syrian hamster (Mesocricetus auratus) during regression owing to short photoperiod

et al. 2015

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SUMMARYDuring 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.

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“…The control of testicular cell population size by apoptosis is part of the regulation circuit of spermatogenesis (Blanco-Rodriguez 1998, Sinha-Hikim & Swerdloff 1999 and has been proposed as a mechanism of testicular regression in several mammals (Furuta et al 1994, Blottner et al 1995, Young & Nelson 2001, Strbenc et al 2003. A functional correlation to apoptotic processes was demonstrated for both TGF-1 and -3 (Ohta et al 1996, Olaso et al 1998a.…”

Section: Introductionmentioning

confidence: 97%

Seasonal variation in expression and localization of testicular transforming growth factors TGF-β1 and TGF-β3 corresponds with spermatogenic activity in roe deer

Wagener¹,

Fickel²,

Schön³

et al. 2005

Journal of Endocrinology

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Adult roe deer males show hormonally controlled seasonal cycles of testicular growth and involution. Mediation of endocrine signals likely requires variable production of testicular growth factors for regulation of testis function. Here we studied the expression pattern of transforming growth factors (TGFs) 1 and 3. Total RNA from testis parenchyma was extracted monthly and analysed using quantitative reverse transcriptase PCR. The localization of mRNAs was determined by in situ hybridization, and corresponding proteins were visualized immunohistochemically. Both factors showed different expression levels and different seasonal expression patterns. The TGF-1 mRNA content was up to 45 times higher than that of TGF-3. Compared with its lowest level in May, TGF-1 expression was slightly enhanced during pre-rut (June/ July). TGF-3 expression increased 5-fold from April to June/July and decreased thereafter to its low in December. This corresponded with changing numbers of spermatocytes and round spermatids, in which both TGF-3 mRNA and the protein were mainly localized. The TGF-1 mRNA was found in interstitial cells, mainly during the non-breeding season, but also in spermatocytes and spermatids during activated spermatogenesis. The translation product was localized in few spermatogenic cells only. The results suggest that TGF-1 and -3 are important in regulating seasonal spermatogenesis of roe deer with diverse functions affecting interstitial and spermatogenic cells.

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Inverse relationship between testicular proliferation and apoptosis in mammalian seasonal breeders

Cited by 48 publications

References 11 publications

Apoptosis is not the cause of seasonal testicular involution in roe deer

Apoptosis is not the cause of seasonal testicular involution in roe deer

Testicular histomorphometry and the proliferative and apoptotic activities of the seminiferous epithelium in Syrian hamster (Mesocricetus auratus) during regression owing to short photoperiod

Seasonal variation in expression and localization of testicular transforming growth factors TGF-β1 and TGF-β3 corresponds with spermatogenic activity in roe deer

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