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Rader MA, Jaime OG, Abarca VO, Young KA. Photoperiod alters testicular methyltransferase complex mRNA expression in Siberian hamsters. Gen Comp Endocrinol 2023; 333:114186. [PMID: 36521516 PMCID: PMC10575611 DOI: 10.1016/j.ygcen.2022.114186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 11/06/2022] [Accepted: 12/07/2022] [Indexed: 12/14/2022]
Abstract
Exposure to long photoperiods stimulates, whereas exposure to short photoperiods transiently inhibit testicular function in Siberian hamsters via well-described neuroendocrine mechanisms. However, less is known about the intra-testicular regulation of these photoperiod-mediated changes. N6-methyladenosine (m6A) is one of the most common mRNA modifications in eukaryotes, with alterations in m6A mRNA methylation affecting testis function and fertility. We hypothesized that genes controlling m6A methylation such as methyltransferase-like-3 (Mettl3) and -14 (Mettl14) and Wilms' tumor-1 associated protein (Wtap), part of an mRNA methylating methyl-transferase complex, or the fat-mass-and-obesity-associated (Fto) and the α-ketoglutarate-dependent dioxygenase alkB homolog-5 (Alkbh5) genes responsible for m6A demethylation, may be differentially regulated by photoperiod in the testis. Male hamsters were exposed to long (LD, control) photoperiod for 14-weeks, short (SD) photoperiod for 2, 5, 8, 11 and 14-weeks to induce regression, or SD for 14-weeks followed by transfer to LD for 1, 2, 4 or 8-weeks to induce recrudescence (post-transfer, PT). SD exposure significantly reduced body, testis, and epididymal masses compared to all other groups. Spermatogenic index, seminiferous tubule diameters and testosterone concentrations significantly decreased in SD as compared to LD, returning to levels no different than LD in post-transfer groups. SD exposure significantly decreased Wtap, Fto, Alkbh5, but increased Mettl14 mRNA expression as compared to LD, with values in PT groups restored to LD levels. Mettl3 mRNA expression did not change. These results suggest that testicular recovery induced by stimulatory photoperiod is relatively rapid, and that the methyltransferase complex may play a role during photostimulated testicular recrudescence.
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Affiliation(s)
- Melanie A Rader
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840, USA
| | - Olga G Jaime
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840, USA
| | - Victor O Abarca
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840, USA
| | - Kelly A Young
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840, USA.
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Zhang Y, Zhu Y, Cao X, Zhang G, Liu S. Cell adhesion function was altered during the seasonal regression of the seminiferous epithelium in the mink species Neovison vison. J Anim Sci 2023; 101:skad190. [PMID: 37282598 PMCID: PMC10276646 DOI: 10.1093/jas/skad190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 06/06/2023] [Indexed: 06/08/2023] Open
Abstract
Minks are seasonal breeders whose seminiferous epithelium undergoes regression through massive germ cell death, leaving only Sertoli cells and spermatogonial cells in the tubules. However, the molecular mechanisms that control this biological process remain largely unknown. This study describes a transcriptomic analysis of mink testes at various reproductive stages (active, regressing, and inactive). A comparison of seminiferous epithelium at different stages of reproduction shows that cell adhesion is altered during regression. In addition, genes and proteins involved in forming the blood-testis barrier (BTB) were examined in sexually active and inactive minks. The seminiferous epithelium in the testes of sexually inactive minks expressed occludin, but this expression was not discernibly observed in the testes of sexually active minks. There was no discernible expression of CX43 in the seminiferous epithelium in the testes of sexually inactive minks, but CX43 was expressed in the testes of sexually active minks. During the regression process, we observed a remarkable increase in the expression levels of Claudin-11, which is associated with Sertoli-germ cell junctions. In conclusion, these findings suggest a loss of Sertoli-germ cell adhesion, which may regulate postmeiotic cell shedding during testicular regression in mink.
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Affiliation(s)
- Yufei Zhang
- College of Veterinary Medicine, Inner Mongolia Agricultural University, Zhao Wu Da Road No. 306, Hohhot 010018, China
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Hohhot 010018, China
- Key Laboratory of Clinical Diagnosis and Treatment Technology in Animal Disease, Ministry of Agriculture, Hohhot 010018, China
| | - Yanzhu Zhu
- Institute of Special Animal and Plant Sciences, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Xiaodong Cao
- School of pharmacy, Inner Mongolia Medical University, Hohhot, Inner Mongolia Autonmous Region, China
- School of pharmacy New Drug Safety Evaluation Research Center, Inner Mongolia Medical University, Hohhot, Inner Mongolia Autonmous Region, China
| | - Guanhua Zhang
- Agriculture and Animal Husbandry Comprehensive Inspection and Testing Center of chifeng, Inner Mongolia, China
| | - Shuying Liu
- College of Veterinary Medicine, Inner Mongolia Agricultural University, Zhao Wu Da Road No. 306, Hohhot 010018, China
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Hohhot 010018, China
- Key Laboratory of Clinical Diagnosis and Treatment Technology in Animal Disease, Ministry of Agriculture, Hohhot 010018, China
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Valentini L, Zupa R, Pousis C, Cuko R, Corriero A. Proliferation and Apoptosis of Cat (Felis catus) Male Germ Cells during Breeding and Non-Breeding Seasons. Vet Sci 2022; 9:vetsci9080447. [PMID: 36006362 PMCID: PMC9414637 DOI: 10.3390/vetsci9080447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/16/2022] [Accepted: 08/18/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Spermatogenesis is a complex process through which male gametes, spermatozoa, are produced starting from stem germ cells called spermatogonia. The existing information on cat spermatogenesis is limited and somewhat contradictory. In fact, although this species is considered a long-day breeder with a reproduction period starting when the day length increases and ending in late autumn, spermatogenesis and sperm production occur throughout the year. In order to assess whether cat spermatogenesis is modulated according to a season pattern, we analyzed testes taken from feral cats orchiectomized during reproductive (February–July) and non-reproductive (November and December) periods. The results of the analyses carried out in the present study showed that spermatogonial proliferation was more intense during the reproductive period and germ cell death via apoptosis (a programmed form of cell death) increased during the non-reproductive period. Our results confirm the hypothesis that cat spermatogenesis is seasonally modulated through changes of germ cell proliferation and apoptosis, according to a common paradigm of seasonally breeding species. Abstract The domestic cat (Felis catus) is a seasonal-breeding species whose reproductive period starts when the day length increases. Since the existing information on cat spermatogenesis is limited and somewhat contradictory, in the present study, germ cell proliferation and apoptosis in feral adult tomcats orchiectomized during reproductive (reproductive group, RG; February–July) and non-reproductive (non-reproductive group, NRG; November and December) seasons were compared. Cross-sections taken from the middle third of the left testis were chemically fixed and embedded in paraffin wax. Histological sections were processed for the immunohistochemical detection of proliferating germ cells (PCNA) and for the identification of apoptotic cells (TUNEL method). The percentage of PCNA-positive spermatogonia was higher in the RG than in the NRG. On the contrary, germ cell apoptosis was higher in the NRG than in the RG. Our results confirm that cat spermatogenesis is modulated on a seasonal basis and suggests that spermatogenesis control involves changes in germ cell proliferation and apoptosis according to a common paradigm of seasonally breeding species.
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Beltrán-Frutos E, Seco-Rovira V, Martínez-Hernández J, Ferrer C, Serrano-Sánchez MI, Pastor LM. Cellular Modifications in Spermatogenesis during Seasonal Testicular Regression: An Update Review in Mammals. Animals (Basel) 2022; 12:ani12131605. [PMID: 35804504 PMCID: PMC9265002 DOI: 10.3390/ani12131605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/15/2022] [Accepted: 06/18/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary The most common form of reproduction in mammals is seasonal reproduction. This ensures that offspring are born at the most suitable time for survival, due to the abundance of food and the optimal temperatures for early postnatal development. In males, one way to achieve this is to decrease or lose fertility over a given period. This loss is associated with a greater or lesser degree of spermatogenesis modification that affects both germ and Sertoli cells. This paper reviews the different cellular mechanisms that have been postulated in recent years to explain how the activity of the seminiferous epithelium decreases during the non-reproductive period. Abstract Testicular regression occurs during the non-breeding season in many mammals. This affects spermatogenesis, resulting in decreased or arrested activity. Both lead to a decrease or cessation in sperm production. In recent years, the cellular mechanisms that lead to infertility in males in non-reproductive periods have been studied in very different species of mammals. At the start of the present century, the main mechanism involved was considered as an increase in the apoptotic activity of germ cells during the regression period. The loss of spermatogonia and spermatocytes causes not only a decrease in spermatogenesis, but an arrest of the seminiferous epithelium activity at the end of regression. Recently, in some mammal species, it was found that apoptosis is the usual mechanism involved in epithelium activity arrest, although it is firstly atrophied by massive desquamation of the germ cells that are released from their binding with the Sertoli cells, and which are shed into the lumen of the seminiferous tubule. In other species, it has been shown that not only germ cell apoptosis, but also Sertoli cell apoptosis, including decreased proliferative activity, spermatophagy or autophagy, are involved in testicular regression. Furthermore, the most recent studies indicate that there are multiple patterns of seminiferous epithelium regression in seasonally breeding animals, which may not only be used by different species, but also by the same ones to reproduce in the best conditions, ensuring their survival. In conclusion, at this time, it is not possible to consider the existence of a paradigmatic cellular mechanism in the involution of the seminiferous epithelium applicable to all male mammals with seasonal reproduction, rather the existence of several mechanisms which participate to a greater or lesser extent in each of the species that have been studied to date.
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Gumułka M, Hrabia A, Rozenboim I. Annual changes in cell proliferation and apoptosis and expression of connexin 43 in the testes of domestic seasonal breeding ganders. Theriogenology 2022; 186:27-39. [DOI: 10.1016/j.theriogenology.2022.03.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 03/27/2022] [Accepted: 03/29/2022] [Indexed: 11/15/2022]
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Akhtar MF, Ahmad E, Ali I, Shafiq M, Chen Z. The Effect of Inhibin Immunization in Seminiferous Epithelium of Yangzhou Goose Ganders: A Histological Study. Animals (Basel) 2021; 11:ani11102801. [PMID: 34679823 PMCID: PMC8532643 DOI: 10.3390/ani11102801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/09/2021] [Accepted: 09/10/2021] [Indexed: 02/05/2023] Open
Abstract
The current study investigated the effect of inhibin immunization on germ cell numbers (spermatogonia, spermatocytes, round, and elongated spermatids), seminiferous tubules (ST) diameter, Johnsen's score, epithelial height (μm), luminal tubular diameter (μm), and number of ST per field (ST/field) of Yangzhou goose ganders. Histological evaluation showed apoptosis and regression of testes after inhibin (INH) immunization, with a concomitantly marked reduction in the round and elongated spermatids in the experiment (INH) group compared to the control group. The diameter of seminiferous tubules (ST) and epithelial height (EH) were positively correlated at 181, 200, and 227 days of age. In comparison, luminal tubular diameter (LD) was negatively correlated on day 227 to ST diameter and epithelial height. On day 227, many seminiferous tubules per field (ST/field) were negatively correlated to ST diameter, EH, and LD. INH immunization elevated ST diameter, EH, and LD, while Johnsen's score and number of ST/field had reciprocal expression. In conclusion, the concomitant effect of INH immunization and seasonality in breeding regressed germ cells and damaged spermatogenesis in seminiferous epithelium Yangzhou ganders.
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Affiliation(s)
- Muhammad Faheem Akhtar
- Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing 210023, China;
| | - Ejaz Ahmad
- Department of Clinical Sciences, Faculty of Veterinary Sciences, Bahauddin Zakariya University, Multan 60800, Pakistan;
| | - Ilyas Ali
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China;
| | - Muhammad Shafiq
- Department of Cell Biology and Genetics, Shantou University Medical College, Shantou 515063, China;
| | - Zhe Chen
- Key Laboratory of Crop and Livestock Integration, Ministry of Agriculture, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
- Correspondence:
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Falvo S, Rosati L, Di Fiore MM, Di Giacomo Russo F, Chieffi Baccari G, Santillo A. Proliferative and Apoptotic Pathways in the Testis of Quail Coturnix coturnix during the Seasonal Reproductive Cycle. Animals (Basel) 2021; 11:ani11061729. [PMID: 34207904 PMCID: PMC8226535 DOI: 10.3390/ani11061729] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 05/27/2021] [Accepted: 05/31/2021] [Indexed: 11/30/2022] Open
Abstract
Simple Summary The quail Coturnix coturnix exhibits an annual cycle of testis size, sexual steroid production, and spermatogenesis. The testicular levels of both 17β-estradiol (E2) and androgens are higher during the reproductive period compared to the non-reproductive period, suggesting that estrogens act in synergy with the androgens for the initiation of spermatogenesis. Therefore, the present study aimed to investigate the estrogen responsive system in quail testis in relation to the reproduction seasons, with a focus on the molecular pathways activated in both active and regressive quail testes. The results indicated that estrogens participated in the activation of mitotic and meiotic events during the reproductive period by activating the ERK1/2 and Akt-1 pathways. In the non-reproductive period, when the E2/ERα levels are low, ERK1/2 and Akt-1 pathways remain inactive and apoptotic events occur. Our results suggest that the activation or inhibition of these molecular pathways plays a crucial role in the physiological switch “on/off” of the testicular activity in male quail during the seasonal reproductive cycle. Abstract The quail Coturnix coturnix is a seasonal breeding species, with the annual reproductive cycle of its testes comprising an activation phase and a regression phase. Our previous results have proven that the testicular levels of both 17β-estradiol (E2) and androgens are higher during the reproductive period compared to the non-reproductive period, which led us to hypothesize that estrogens and androgens may act synergistically to initiate spermatogenesis. The present study was, therefore, aimed to investigate the estrogen responsive system in quail testis in relation to the reproduction seasonality, with a focus on the molecular pathways elicited in both active and regressive quail testes. Western blotting and immunohistochemistry analysis revealed that the expression of ERα, which is the predominant form of estrogen receptors in quail testis, was correlated with E2 concentration, suggesting that increased levels of E2-induced ERα could play a key role in the resumption of spermatogenesis during the reproductive period, when both PCNA and SYCP3, the mitotic and meiotic markers, respectively, were also increased. In the reproductive period we also found the activation of the ERK1/2 and Akt-1 kinase pathways and an increase in second messengers cAMP and cGMP levels. In the non-reproductive phase, when the E2/ERα levels were low, the inactivation of ERK1/2 and Akt-1 pathways favored apoptotic events due to an increase in the levels of Bax and cytochrome C, with a consequent regression of the gonad.
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Affiliation(s)
- Sara Falvo
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania “Luigi Vanvitelli”, 81100 Caserta, Italy; (S.F.); (M.M.D.F.); (F.D.G.R.); (G.C.B.)
| | - Luigi Rosati
- Dipartimento di Biologia, Università degli Studi di Napoli “Federico II”, 80138 Napoli, Italy;
| | - Maria Maddalena Di Fiore
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania “Luigi Vanvitelli”, 81100 Caserta, Italy; (S.F.); (M.M.D.F.); (F.D.G.R.); (G.C.B.)
| | - Federica Di Giacomo Russo
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania “Luigi Vanvitelli”, 81100 Caserta, Italy; (S.F.); (M.M.D.F.); (F.D.G.R.); (G.C.B.)
| | - Gabriella Chieffi Baccari
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania “Luigi Vanvitelli”, 81100 Caserta, Italy; (S.F.); (M.M.D.F.); (F.D.G.R.); (G.C.B.)
| | - Alessandra Santillo
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania “Luigi Vanvitelli”, 81100 Caserta, Italy; (S.F.); (M.M.D.F.); (F.D.G.R.); (G.C.B.)
- Correspondence:
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Mediterranean Pine Vole, Microtus duodecimcostatus: A Paradigm of an Opportunistic Breeder. Animals (Basel) 2021; 11:ani11061639. [PMID: 34205873 PMCID: PMC8228771 DOI: 10.3390/ani11061639] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 05/23/2021] [Accepted: 05/27/2021] [Indexed: 12/12/2022] Open
Abstract
Simple Summary In temperate zones of the Earth, some mammalian species reproduce seasonally whereas others do it continuously. Other species are summer breeders in the north and winter breeders in the south. Thus, the reproductive pattern seems not to be a species-specific but a population-specific trait. We investigated the reproduction pattern of the Mediterranean pine vole, Microtus duodecimcostatus, in the area around the city of Granada in Southern Spain, and found that individuals living in wastelands reproduce seasonally whereas those living in close poplar plantations (just 8 km apart) reproduce throughout the year, as did voles captured in wastelands and kept in captivity. These animals represent thus a paradigm of an opportunistic breeder as particular individuals stop breeding or not, depending on the environmental conditions they face at any moment. Sexually inactive male voles undergo complete testis inactivation and their sperm production is halted. The immune system in active testes is depressed, a phenomenon known as “immune privilege” that protect germ cells from autoimmune attack. We studied gene activity in active and inactive testes and our results indicate that such an immune privilege is lost in inactive testes, suggesting an important role for this process during testis regression. Abstract Most mammalian species of the temperate zones of the Earth reproduce seasonally, existing a non-breeding period in which the gonads of both sexes undergo functional regression. It is widely accepted that photoperiod is the principal environmental cue controlling these seasonal changes, although several exceptions have been described in other mammalian species in which breeding depends on cues such as food or water availability. We studied the circannual reproductive cycle in males of the Mediterranean pine vole, Microtus duodecimcostatus, in the Southeastern Iberian Peninsula. Morphological, hormonal, functional, molecular and transcriptomic analyses were performed. As reported for populations of other species from the same geographic area, male voles captured in wastelands underwent seasonal testis regression in summer whereas, surprisingly, those living either in close poplar plantations or in our animal house reproduced throughout the year, showing that it is the microenvironment of a particular vole subpopulation what determines its reproductive status and that these animals are pure opportunistic, photoperiod-independent breeders. In addition, we show that several molecular pathways, including MAPK, are deregulated and that the testicular “immune privilege” is lost in the inactive testes, providing novel mechanisms linking seasonal testosterone reduction and testis regression.
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Banerjee S, Chaturvedi CM. Apoptotic mechanism behind the testicular atrophy in photorefractory and scotosensitive quail: Involvement of GnIH induced p-53 dependent Bax-Caspase-3 mediated pathway. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2017; 176:124-135. [DOI: 10.1016/j.jphotobiol.2017.09.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 09/25/2017] [Accepted: 09/28/2017] [Indexed: 12/17/2022]
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Davies S, Lane S, Meddle SL, Tsutsui K, Deviche P. The ecological and physiological bases of variation in the phenology of gonad growth in an urban and desert songbird. Gen Comp Endocrinol 2016; 230-231:17-25. [PMID: 26972152 PMCID: PMC4890648 DOI: 10.1016/j.ygcen.2016.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 01/09/2023]
Abstract
Birds often adjust to urban areas by advancing the timing (phenology) of vernal gonad growth. However, the ecological and physiological bases of this adjustment are unclear. We tested whether the habitat-related disparity in gonad growth phenology of male Abert's towhees, Melozone aberti, is due to greater food availability in urban areas of Phoenix, Arizona USA or, alternatively, a habitat-related difference in the phenology of key food types. To better understand the physiological mechanism underlying variation in gonad growth phenology, we compared the activity of the reproductive system at all levels of hypothalamo-pituitary-gonadal (HPG) axis. We found no habitat-associated difference in food availability (ground arthropod biomass), but, in contrast to the seasonal growth of leaves on desert trees, the leaf foliage of urban trees was already developed at the beginning of our study. Multiple estimates of energetic status did not significantly differ between the non-urban and urban towhees during three years that differed in the habitat-related disparity in gonad growth and winter precipitation levels. Thus, our results provide no support for the hypothesis that greater food abundance in urban areas of Phoenix drives the habitat-related disparity in gonad growth phenology in Abert's towhees. By contrast, they suggest that differences in the predictability and magnitude of change in food availability between urban and desert areas of Phoenix contribute to the observed habitat-related disparity in gonad growth. Endocrine responsiveness of the gonads may contribute to this phenomenon as desert - but not urban - towhees had a marked plasma testosterone response to GnRH challenge.
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Affiliation(s)
- Scott Davies
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA.
| | - Samuel Lane
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Simone L Meddle
- The Roslin Institute & Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian EH25 9PS, UK
| | - Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo 162-8480, Japan
| | - Pierre Deviche
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
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Abdul-Rahman I, Robinson J, Obese F, Jeffcoate I, Awumbila B. Effects of season on the reproductive organ and plasma testosterone concentrations in guinea cocks (Numida meleagris). Poult Sci 2016; 95:636-44. [DOI: 10.3382/ps/pev342] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 09/28/2015] [Indexed: 11/20/2022] Open
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Jiménez R, Burgos M, Barrionuevo FJ. Circannual Testis Changes in Seasonally Breeding Mammals. Sex Dev 2015; 9:205-15. [PMID: 26375035 DOI: 10.1159/000439039] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2015] [Indexed: 11/19/2022] Open
Abstract
In the non-equatorial zones of the Earth, species concentrate their reproductive effort in the more favorable season. A consequence of seasonal breeding is seasonal testis regression, which implies the depletion of the germinative epithelium, permeation of the blood-testis barrier, and reduced androgenic function. This process has been studied in a number of vertebrates, but the mechanisms controlling it are not yet well understood. Apoptosis was assumed for years to be an important effector of seasonal germ cell depletion in all vertebrates, including mammals, but an alternative mechanism has recently been reported in the Iberian mole as well as in the large hairy armadillo. It is based on the desquamation of meiotic and post-meiotic germ cells as a consequence of altered Sertoli-germ cell adhesion molecule expression and distribution. Desquamated cells are either discarded alive through the epididymis, as in the mole, or subsequently die by apoptosis, as in the armadillo. Also, recent findings on the reproductive cycle of the greater white-toothed shrew at the meridional limits of its distribution area have revealed that the mechanisms controlling seasonal breeding are in fact far more plastic and versatile than initially suspected. Perhaps these higher adaptive capacities place mammals in a better position to face the ongoing climate change.
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Affiliation(s)
- Rafael Jiménez
- Departamento de Genx00E9;tica e Instituto de Biotecnologx00ED;a, Universidad de Granada, Granada, Spain
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Davies S, Cros T, Richard D, Meddle SL, Tsutsui K, Deviche P. Food availability, energetic constraints and reproductive development in a wild seasonally breeding songbird. Funct Ecol 2015; 29:1421-1434. [PMID: 27546946 PMCID: PMC4974902 DOI: 10.1111/1365-2435.12448] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 03/23/2015] [Indexed: 11/28/2022]
Abstract
In many organisms, food availability is a proximate cue that synchronizes seasonal development of the reproductive system with optimal environmental conditions. Growth of the gonads and secondary sexual characteristics is orchestrated by the hypothalamic–pituitary–gonadal (HPG) axis. However, our understanding of the physiological mechanisms by which food availability modulates activity of the HPG axis is limited. It is thought that many factors, including energetic status, modulate seasonal reproductive activation. We tested the hypothesis that food availability modulates the activity of the HPG axis in a songbird. Specifically, we food‐restricted captive adult male Abert's Towhees Melozone aberti for 2 or 4 weeks during photoinduced reproductive development. A third group (control) received ad libitum food throughout. We measured multiple aspects of the reproductive system including endocrine activity of all three levels of the HPG axis [i.e. hypothalamic gonadotropin‐releasing hormone‐I (GnRH‐I), plasma luteinizing hormone (LH) and testosterone (T)], and gonad morphology. Furthermore, because gonadotropin‐inhibitory hormone (GnIH) and neuropeptide Y (NPY; a potent orexigenic peptide) potentially integrate information on food availability into seasonal reproductive development, we also measured the brain levels of these peptides. At the hypothalamic level, we detected no effect of food restriction on immunoreactive (ir) GnRH‐I, but the duration of food restriction was inversely related to the size of ir‐GnIH perikarya. Furthermore, the number of ir‐NPY cells was higher in food‐restricted than control birds. Food restriction did not influence photoinduced testicular growth, but decreased plasma LH and T, and width of the cloacal protuberance, an androgen‐sensitive secondary sexual characteristic. Returning birds to ad libitum food availability had no effect on plasma LH or T, but caused the cloacal protuberance to rapidly increase in size to that of ad libitum‐fed birds. Our results support the tenet that food availability modulates photoinduced reproductive activation. However, they also suggest that this modulation is complex and depends upon the level of the HPG axis considered. At the hypothalamic level, our results are consistent with a role for the GnIH and NPY systems in integrating information on energetic status. There also appears to be a role for endocrine function at the anterior pituitary gland and testicular levels in modulating reproductive development in the light of energetic status and independently of testicular growth.
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Affiliation(s)
- Scott Davies
- School of Life Sciences Arizona State University Tempe Arizona 85287 USA; Present address: Department of Biological Sciences Virginia Tech Blacksburg Virginia 24061USA
| | - Thomas Cros
- Faculté des Sciences Fondamentales et Appliquées Université de Poitiers Poitiers 86022 France
| | - Damien Richard
- Faculté des Sciences Fondamentales et Appliquées Université de Poitiers Poitiers 86022 France
| | - Simone L Meddle
- The Roslin Institute The Royal (Dick) School of Veterinary Studies The University of Edinburgh Easter Bush Midlothian EH25 9RG UK
| | - Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences Department of Biology and Center for Medical Life Science Waseda University Tokyo 162-8480 Japan
| | - Pierre Deviche
- School of Life Sciences Arizona State University Tempe Arizona 85287 USA
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14
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Seco-Rovira V, Beltrán-Frutos E, Ferrer C, Saez FJ, Madrid JF, Canteras M, Pastor LM. Testicular histomorphometry and the proliferative and apoptotic activities of the seminiferous epithelium in Syrian hamster (Mesocricetus auratus) during regression owing to short photoperiod. Andrology 2015; 3:598-610. [DOI: 10.1111/andr.12037] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 02/09/2015] [Accepted: 03/05/2015] [Indexed: 12/13/2022]
Affiliation(s)
- 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. 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. Ferrer
- Department of Cell Biology and Histology; Medical School; IMIB-Arrixaca; Regional Campus of International Excellence Campus Mare Nostrum, University of Murcia; Murcia Spain
| | - F. J. Saez
- Department of Cell Biology and Histology UFI 11/44; School of Medicine and Dentistry; University of the Basque Country UPV/EHU; Leioa Spain
| | - J. F. Madrid
- Department of Cell Biology and Histology; Medical School; IMIB-Arrixaca; Regional Campus of International Excellence Campus Mare Nostrum, University of Murcia; Murcia Spain
| | - M. Canteras
- Department of Statistics; Medical School; University of Murcia; Murcia Spain
| | - L. M. Pastor
- Department of Cell Biology and Histology; Medical School; IMIB-Arrixaca; Regional Campus of International Excellence Campus Mare Nostrum, University of Murcia; Murcia Spain
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15
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A mechanism of male germ cell apoptosis induced by bisphenol-A and nonylphenol involving ADAM17 and p38 MAPK activation. PLoS One 2014; 9:e113793. [PMID: 25474107 PMCID: PMC4256297 DOI: 10.1371/journal.pone.0113793] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 10/30/2014] [Indexed: 01/08/2023] Open
Abstract
Germ cell apoptosis regulation is pivotal in order to maintain proper daily sperm production. Several reports have shown that endocrine disruptors such as Bisphenol-A (BPA) and Nonylphenol (NP) induce germ cell apoptosis along with a decrease in sperm production. Given their ubiquitous distribution in plastic products used by humans it is important to clarify their mechanism of action. TACE/ADAM17 is a widely distributed extracellular metalloprotease and participates in the physiological apoptosis of germ cells during spermatogenesis. The aims of this work were: 1) to determine whether BPA and NP induce ADAM17 activation; and 2) to study whether ADAM17 and/or ADAM10 are involved in germ cell apoptosis induced by BPA and NP in the pubertal rat testis. A single dose of BPA or NP (50 mg/kg) induces germ cell apoptosis in 21-day-old male rats, which was prevented by a pharmacological inhibitor of ADAM17, but not by an inhibitor of ADAM10. In vitro, we showed that BPA and NP, at similar concentrations to those found in human samples, induce the shedding of exogenous and endogenous (TNF-α) ADAM17 substrates in primary rat Sertoli cell cultures and TM4 cell line. In addition, pharmacological inhibitors of metalloproteases and genetic silencing of ADAM17 prevent the shedding induced in vitro by BPA and NP. Finally, we showed that in vivo BPA and NP induced early activation (phosphorylation) of p38 MAPK and translocation of ADAM17 to the cell surface. Interestingly, the inhibition of p38 MAPK prevents germ cell apoptosis and translocation of ADAM17 to the cell surface. These results show for the first time that xenoestrogens can induce activation of ADAM17 at concentrations similar to those found in human samples, suggesting a mechanism by which they could imbalance para/juxtacrine cell-to-cell-communication and induce germ cell apoptosis.
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16
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Massoud D, Barrionuevo FJ, Ortega E, Burgos M, Jiménez R. The testis of greater white-toothed shrew Crocidura russula in Southern European populations: a case of adaptive lack of seasonal involution? JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2014; 322:304-15. [PMID: 24895181 DOI: 10.1002/jez.b.22582] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 05/19/2014] [Indexed: 11/08/2022]
Abstract
Males of all seasonal breeding mammals undergo circannual periods of testis involution resulting in almost complete ablation of the germinative epithelium. We performed a morphometric, histological, hormonal, and gene-expression study of the testes from winter and summer males of the greater white-toothed shrew, Crocidura russula, in populations of the southeastern Iberian Peninsula. Unexpectedly, we found no significant differences between the two study groups. Surprisingly, female data confirmed a non-breeding period in the summer, evidencing that males retain full testis function even when most females are not receptive. This situation, which has not been described before, does not occur in northern populations of the same species where, in addition, the reproductive cycle is inverted with respect to those in the south, as the non-breeding period occurs in winter instead in summer. Considering that the non-reproductive period shortens at lower latitude locations, we hypothesize that in southern populations the non-breeding period is short enough to make testis regression inefficient in terms of energy savings, because: (1) testes of C. russula are very small, a condition derived from their monogamy that implies low investment in spermatogenesis; and (2) the spermatogenic cycle of this species is slow and long. The inverted seasonal breeding cycle and the lack of seasonal testis regression described here are new adaptive processes that deserve further research, and provide evidence that the genetic and hormonal mechanisms controlling reproduction timing in mammals are more plastic and versatile than initially suspected.
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Affiliation(s)
- Diaa Massoud
- Departamento de Genética e Instituto de Biotecnología, Universidad de Granada, Granada, Spain
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17
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Seco-Rovira V, Beltrán-Frutos E, Ferrer C, Sáez FJ, Madrid JF, Pastor LM. The death of sertoli cells and the capacity to phagocytize elongated spermatids during testicular regression due to short photoperiod in Syrian hamster (Mesocricetus auratus). Biol Reprod 2014; 90:107. [PMID: 24719257 DOI: 10.1095/biolreprod.113.112649] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
In the Syrian hamster (Mesocricetus auratus), an animal that displays testicular regression due to short photoperiod, germ cells are removed by apoptosis during this process and the apoptotic remains are phagocytized by Sertoli cells. The aim of this work was to investigate morphologically whether the testicular regression process due to short photoperiod leads to the apoptosis of Sertoli cells, and whether, during testicular regression, the elongated spermatids are eliminated through phagocytosis by Sertoli cells. To this end, we studied testis sections during testicular regression in Syrian hamster subjected to short photoperiod by means of several morphological techniques using conventional light microscopy (hematoxylin and eosin [H&E], semi-thin section vimentin, immunohistochemistry, SBA lectin, and TUNEL staining), fluorescence microscopy, and transmission electron microscopy (TEM). H&E and semi-thin sections identified Sertoli cells with a degenerated morphology. Greater portion of Sertoli cells that were positive for TUNEL staining were observed especially during the mild regression (MR) and strong regression (SR) phases. In addition, TEM identified the characteristic apoptotic changes in the nucleus and cytoplasm of Sertoli cells. Moreover, during testicular regression and using light microscopy, some elongated spermatids were seen in basal position next to the Sertoli cell nucleus. This Sertoli phagocytic activity was higher in MR and SR phases. TEM confirmed this to be the result of the phagocytic activity of Sertoli cells. In conclusion, during testicular regression in Syrian hamster due to short photoperiod, when germ cells are known to be lost through apoptosis, there is morphological evidences that Sertoli cells are also lost through apoptosis, while some elongated spermatids are phagocytized and eliminated by the Sertoli cells.
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Affiliation(s)
- Vicente Seco-Rovira
- Department of Cell Biology and Histology, Medical School, Instituto Murciano de Investigación Biosanitaria, Regional Campus of International Excellence "Campus Mare Nostrum," University of Murcia, Murcia, Spain
| | - Esther Beltrán-Frutos
- Department of Cell Biology and Histology, Medical School, Instituto Murciano de Investigación Biosanitaria, Regional Campus of International Excellence "Campus Mare Nostrum," University of Murcia, Murcia, Spain
| | - Concepción Ferrer
- Department of Cell Biology and Histology, Medical School, Instituto Murciano de Investigación Biosanitaria, Regional Campus of International Excellence "Campus Mare Nostrum," University of Murcia, Murcia, Spain
| | - Francisco José Sáez
- Department of Cell Biology and Histology Unidad de Formación e Investigación 11/44, School of Medicine and Dentistry, University of the Basque Country Universidad del País Vasco/Euskal Herrico Unibertsitatea, Leioa, Spain
| | - Juan Francisco Madrid
- Department of Cell Biology and Histology, Medical School, Instituto Murciano de Investigación Biosanitaria, Regional Campus of International Excellence "Campus Mare Nostrum," University of Murcia, Murcia, Spain
| | - Luis Miguel Pastor
- Department of Cell Biology and Histology, Medical School, Instituto Murciano de Investigación Biosanitaria, Regional Campus of International Excellence "Campus Mare Nostrum," University of Murcia, Murcia, Spain
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18
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Seco-Rovira V, Beltrán-Frutos E, Ferrer C, Sánchez-Huertas MM, Madrid JF, Saez FJ, Pastor LM. Lectin Histochemistry as a Tool to Identify Apoptotic Cells in the Seminiferous Epithelium of Syrian Hamster (Mesocricetus auratus) Subjected to Short Photoperiod. Reprod Domest Anim 2013; 48:974-83. [DOI: 10.1111/rda.12196] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 05/15/2013] [Indexed: 02/05/2023]
Affiliation(s)
- V Seco-Rovira
- Department of Cell Biology and Histology, Medical School, IMIB, Regional Campus of International Excellence ‘Campus Mare Nostrum’; University of Murcia; Murcia Spain
| | - E Beltrán-Frutos
- Department of Cell Biology and Histology, Medical School, IMIB, Regional Campus of International Excellence ‘Campus Mare Nostrum’; University of Murcia; Murcia Spain
| | - C Ferrer
- Department of Cell Biology and Histology, Medical School, IMIB, Regional Campus of International Excellence ‘Campus Mare Nostrum’; University of Murcia; Murcia Spain
| | - MM Sánchez-Huertas
- Department of Cell Biology and Histology, Medical School, IMIB, Regional Campus of International Excellence ‘Campus Mare Nostrum’; University of Murcia; Murcia Spain
| | - JF Madrid
- Department of Cell Biology and Histology, Medical School, IMIB, Regional Campus of International Excellence ‘Campus Mare Nostrum’; University of Murcia; Murcia Spain
| | - FJ Saez
- Department of Cell Biology and Histology UFI11/44, School of Medicine and Dentistry; University of the Basque Country, UPV/EHU; Leioa Spain
| | - LM Pastor
- Department of Cell Biology and Histology, Medical School, IMIB, Regional Campus of International Excellence ‘Campus Mare Nostrum’; University of Murcia; Murcia Spain
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19
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Dadhich RK, Barrionuevo FJ, Real FM, Lupiañez DG, Ortega E, Burgos M, Jiménez R. Identification of live germ-cell desquamation as a major mechanism of seasonal testis regression in mammals: a study in the Iberian mole (Talpa occidentalis). Biol Reprod 2013; 88:101. [PMID: 23515671 DOI: 10.1095/biolreprod.112.106708] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In males of seasonally breeding species, testes undergo a severe involution at the end of the breeding season, with a major volume decrease due to massive germ-cell depletion associated with photoperiod-dependent reduced levels of testosterone and gonadotropins. Although it has been repeatedly suggested that apoptosis is the principal effector of testicular regression in vertebrates, recent studies do not support this hypothesis in some mammals. The purpose of our work is to discover alternative mechanisms of testis regression in these species. In this paper, we have performed a morphological, hormonal, ultrastructural, molecular, and functional study of the mechanism of testicular regression and the role that cell junctions play in the cell-content dynamics of the testis of the Iberian mole, Talpa occidentalis, throughout the seasonal breeding cycle. Desquamation of live, nonapoptotic germ cells has been identified here as a new mechanism for seasonal testis involution in mammals, indicating that testis regression is regulated by modulating the expression and distribution of the cell-adhesion molecules in the seminiferous epithelium. During this process, which is mediated by low intratesticular testosterone levels, Sertoli cells lose their nursing and supporting function, as well as the impermeability of the blood-testis barrier. Our results contradict the current paradigm that apoptosis is the major testis regression effector in vertebrates, as it is clearly not true in all mammals. The new testis regression mechanism described here for the mole could then be generalized to other mammalian species. Available data from some previously studied mammals should be reevaluated.
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Affiliation(s)
- Rajesh K Dadhich
- Departamento de Genética, Instituto de Biotecnología, Universidad de Granada, Granada, Spain
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20
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Islam MN, Tsukahara N, Sugita S. Apoptosis-mediated seasonal testicular regression in the Japanese Jungle crow (Corvus macrorhynchos). Theriogenology 2012; 77:1854-65. [DOI: 10.1016/j.theriogenology.2012.01.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2010] [Revised: 01/05/2012] [Accepted: 01/06/2012] [Indexed: 10/28/2022]
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21
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Pastor LM, Zuasti A, Ferrer C, Bernal-Mañas CM, Morales E, Beltrán-Frutos E, Seco-Rovira V. Proliferation and apoptosis in aged and photoregressed mammalian seminiferous epithelium, with particular attention to rodents and humans. Reprod Domest Anim 2011; 46:155-64. [PMID: 20149139 DOI: 10.1111/j.1439-0531.2009.01573.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Imbalances in the proliferation and apoptosis processes are involved in numerous epithelial alterations. In the seminiferous epithelium, normal spermatogenesis is regulated by spermatogonia proliferation and germ cell apoptosis, and both processes are involved in diverse pathological alterations of the seminiferous epithelium. Other physiological phenomena including aging and short photoperiod, in which apoptosis and proliferation seem to play important roles, cause testicular changes. Aging is accompanied by diminished proliferation and increased apoptosis, the latter occurring in specific states of the seminiferous cycle and considered the cause of epithelium involution. However, there is no clear evidence concerning whether proliferation decreases in the spermatogonia themselves or is due to an alteration in the cell microenvironment that surrounds them. As regards the factors that regulate the process, the data are scant, but it is considered that the diminution of c-kit expression in the spermatagonia, together with the diminution in antiapoptotic factors (Bcl-x(L))) of the intrinsic molecular pathway of apoptosis play a part in epithelial regression. A short photoperiod, especially in rodents, produces a gradual involution of the seminiferous epithelium, which is related with increased apoptosis during the regression phase and a diminution of apoptosis during recrudescence. Proliferative activity varies, especially during the total regression phase, when it usually increases in the undifferentiated spermatogonia. In other species showing seasonal reproduction, however, decreased proliferation is considered the main factor in the regression of the seminiferous epithelium. Little is known about how both phenomena are regulated, although data in rodents suggest that both the intrinsic and extrinsic pathways of apoptosis contribute to the increase in this process. In conclusion, regression of the seminiferous epithelium in physiological situations, as in many pathological situations, is a result of alterations in equilibrium between the proliferation and apoptosis of germinal cell types. However, both physiological phenomena showed important differences as regard proliferation/apoptosis and their regulation pathways, probably as a result of their irreversible or reversible character.
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Affiliation(s)
- L M Pastor
- Department of Cellular Biology and Histology, Aging Institute, Medical School, University of Murcia, Murcia, Spain.
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22
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Histological and morphometric analyses of seasonal testicular variations in the Jungle Crow (Corvus macrorhynchos). Anat Sci Int 2009; 85:121-9. [PMID: 19937424 DOI: 10.1007/s12565-009-0066-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Accepted: 10/16/2009] [Indexed: 10/20/2022]
Abstract
A histological and morphometric study was conducted to examine the seasonal testicular variations in the Jungle Crow (Corvus macrorhynchos) of the Kanto area, Japan, from January to July. The paired testes mass, diameter and number of germ cells of the seminiferous tubules, and proportion of seminiferous tubule area and interstitium were examined. Hematoxylin and eosin-stained testis sections and ImageJ Software were used. Paired testes weight was found to increase by 55-fold from January to late March-early May, thereafter declining by 18-fold by June-July. Seminiferous tubule diameter increased fivefold from January to late March-early May, followed a fourfold decrease in June-July. The increase in testes weight correlated well with the increase in the diameter of the seminiferous tubule. In January, the seminiferous tubules constituted 56% of the testicular tissue and the interstitium 44%. During late March-early May, there was very little testicular interstitium (7.9%), and the seminiferous tubules were significantly enlarged (P < 0.05) (92%); this was followed by a gradual increase in the interstitial regression of testes. In January, the seminiferous epithelium contained a single layer of spermatogonia and Sertoli cells. The number of spermatogonia, primary and secondary spermatocytes, spermatids, and maturing spermatozoa were significantly increased (P < 0.05) in late March-early May, followed by regression from mid May. Our results indicate that the Jungle Crow has a non-breeding season in January, a pre-breeding season during February-mid March, a main breeding season during late March-early May, a transition period during mid May-late May, and a post-breeding season beginning in June.
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23
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Mull CG, Lowe CG, Young KA. Photoperiod and water temperature regulation of seasonal reproduction in male round stingrays (Urobatis halleri). Comp Biochem Physiol A Mol Integr Physiol 2008; 151:717-25. [DOI: 10.1016/j.cbpa.2008.08.029] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Revised: 08/18/2008] [Accepted: 08/18/2008] [Indexed: 11/28/2022]
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