scholarly journals 268 GERM CELL DEVELOPMENT IN EQUINE TESTIS TISSUE XENOGRAFTED INTO MICE

2005 ◽  
Vol 17 (2) ◽  
pp. 283 ◽  
Author(s):  
R. Turner ◽  
R. Rathi ◽  
A. Honaramooz ◽  
W. Zeng ◽  
I. Dobrinski
Keyword(s):  
Chorionic Gonadotropin ◽  
Germ Cells ◽  
Seminal Vesicles ◽  
Post Transplantation ◽  
Immunodeficient Mice ◽  
Donor Tissue ◽  
Old Donor ◽  
Pachytene Spermatocytes ◽  
Donor Species ◽  
Testis Tissue

Grafting of testis tissue from immature animals under the back skin of immunodeficient mice results in complete spermatogenesis, albeit with different levels of efficiency in different species. While spermatogenesis develops comparably to that in the donor species in xenografts from pigs, sheep and goats, spermatogenic differentiation is less efficient in testis tissue from cats and bulls. Testicular maturation was significantly accelerated in rhesus monkey testis grafts whereas timing was similar to that in the donor species in cats and bulls. The objective of this study was to investigate if grafting of immature horse testis tissue would result in spermatogenesis in a mouse host. Small fragments of testis tissue (about 1 mm3) from four sexually immature colts (2-week-old Standardbred, 5- and 8-month-old ponies, 10-month-old Warmblood) were grafted under the back skin of castrated male immunodeficient mice (n = 5, 5, 10 and 5 recipient mice, respectively). Histological examination of the testis xenografts was performed between 14 and 50 week post-transplantation. Weight of the seminal vesicles in the host mouse was recorded as an indicator of bioactive testosterone produced by the xenografts. At the time of grafting, the seminiferous cords of the donor testis tissue form 2-week-, 5-month- and 8-month-old colts contained only immature Sertoli cells and gonocytes. No spermatogenic differentiation occurred in xenografts from the 2-week-old colt and testosterone production was minimal. Pachytene spermatocytes were observed in testis grafts from the 5- and 8-month-old donors from 14 weeks onward. Spermatogenesis did not proceed through meiosis in grafts from the 5-month-old donor. Recipient mice carrying xenografts from the 8-month-old donor received exogenous gonadotropins (equine chorionic gonadotropin and human chorionic gonadotropin, 10 I.U./day for 2 months, beginning 14 weeks after grafting) and condensing spermatids were observed by 35 weeks after grafting. In donor tissue from the 10-month-old colt, pachytene spermatocytes were present in about 50% of tubules at the time of grafting. After 14 weeks, xenografts showed fewer differentiated germ cells than the donor tissue. However, at 35 weeks after grafting, condensing spermatids were observed, indicating that differentiated germ cells were initially lost and spermatogenesis was subsequently reinitiated. In all castrated host mice where spermatogenic differentiation occurred, the weight of the seminal vesicles was restored to pre-castration values showing that xenografts were releasing bioactive testosterone. These results indicate that horse spermatogenesis can occur in a mouse host albeit with low efficiency. Testicular maturation was not accelerated. In most cases, spermatogenesis appeared to become arrested at meiosis. The underlying mechanisms of this spermatogenic arrest require further investigation. Although equine testis xenografts produced testosterone, supplementation of exogenous gonadotropins might support post-meiotic differentiation. This work was supported by USDA 03-35203-13486.

scholarly journals Germ cell development in equine testis tissue xenografted into mice

Reproduction ◽  
2006 ◽  
Vol 131 (6) ◽  
pp. 1091-1098 ◽  
Author(s):  
R Rathi ◽  
A Honaramooz ◽  
W Zeng ◽  
R Turner ◽  
I Dobrinski
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Meiotic Division ◽  
Seminal Vesicles ◽  
Post Transplantation ◽  
Germ Cell Development ◽  
Immunodeficient Mice ◽  
Low Efficiency ◽  
Underlying Mechanisms ◽  
Testis Tissue

Grafting of testis tissue from immature animals to immunodeficient mice results in complete spermatogenesis, albeit with varying efficiency in different species. The objectives of this study were to investigate if grafting of horse testis tissue would result in spermatogenesis, and to assess the effect of exogenous gonadotropins on xenograft development. Small fragments of testis tissue from 7 colts (2 week to 4 years of age) were grafted under the back skin of castrated male immunodeficient mice. For 2 donor animals, half of the mice were treated with gonadotropins. Xenografts were analyzed at 4 and 8 months post-transplantation. Spermatogenic differentiation following grafting ranged from no differentiation to progression through meiosis with appearance of haploid cells. Administration of exogenous gonadotropins appeared to support post-meiotic differentiation. For more mature donor testis samples where spermatogenesis had progressed into or through meiosis, after grafting an initial loss of differentiated germ cells was observed followed by a resurgence of spermatogenesis. However, if haploid cells had been present prior to grafting, spermatogenesis did not progress beyond meiotic division. In all host mice with spermatogenic differentiation in grafts, increased weight of the seminal vesicles compared to castrated mice showed that xenografts were releasing testosterone. These results indicate that horse spermatogenesis occurs in a mouse host albeit with low efficiency. In most cases, spermatogenesis arrested at meiosis. The underlying mechanisms of this spermatogenic arrest require further investigation.

scholarly journals 193 TESTIS TISSUE XENOGRAFTING TO PRESERVE GERM CELLS FROM A CLONED BANTENG CALF

2005 ◽  
Vol 17 (2) ◽  
pp. 247 ◽  
Author(s):  
A. Honaramooz ◽  
W. Zeng ◽  
R. Rathi ◽  
J. Koster ◽  
O. Ryder ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Seminal Vesicles ◽  
Male Germ Cells ◽  
Newborn Animal ◽  
Immunodeficient Mice ◽  
Germ Cell Differentiation ◽  
Pachytene Spermatocytes ◽  
The Right ◽  
Testis Tissue

In April 2003, two banteng (Bos javonicus) calves were born after heterologous nuclear transfer of donor cells from a genetically valuable individual frozen in 1978. One of the cloned banteng calves died at one week of age. The calf was found to have one scrotal and one abdominally cryptorchid testis. In an attempt to preserve male germ cells from this valuable animal, parts of each testis were shipped on ice to the University of Pennsylvania for xenografting. Grafting of testis tissue from immature domestic animals and monkeys under the back skin of immunodeficient mice can result in complete spermatogenesis, albeit with different levels of efficiency in different species. The objective of this experiment was to investigate if grafting of immature banteng testis tissue would result in spermatogenesis in a mouse host. Small fragments of tissue (about 1 mm, 3 each) from both testes were grafted under the back skin (4 pieces of scrotal testis on the right side and 4 pieces of retained testis on the left side) of 6 castrated male immunodeficient mice. Histological examination of the testis xenografts was performed 3, 6, 9, 12, and 15 months after transplantation. Weight of the seminal vesicles in the host mouse was recorded as an indicator of bioactive testosterone produced by the xenografts. At the time of grafting, both testes contained seminiferous cords with immature Sertoli cells and gonocytes. At 3, 6, and 9 months after grafting, pachytene spermatocytes were present in the xenografts of the scrotal testis whereas no germ cell differentiation was observed in grafts from the retained testis. However, spermatogenesis in grafts of the scrotal testis did not proceed further through meiosis in grafts analyzed at 12 and 15 months after grafting, with pachytene spermatocytes still the most advanced germ cell type present in grafts recovered 15 months after grafting. The weight of the seminal vesicles in the castrated host mice was restored to pre-castration values showing that xenografts were releasing bioactive testosterone. These results indicate that banteng spermatogenesis was initiated in the mouse host but became arrested at meiosis as observed previously in xenografts of immature bovine or equine testis. Therefore, haploid germ cells could not be recovered. This represents the first example of trying to preserve fertility from a rare, valuable newborn animal by testis tissue xenografting. While xenografting presents a previously unavailable option for preservation of male germ cells from immature individuals, the efficiency of sperm production in testis xenografts appears to be variable and has to be determined empirically for different donor species. This work was supported by USDA 03-35203-13486.

scholarly journals 267 TESTIS TISSUE XENOGRAFTING AS A BIOASSAY FOR GERM CELL DEVELOPMENTAL POTENTIAL IN EQUINE CRYPTORCHID TESTES

2005 ◽  
Vol 17 (2) ◽  
pp. 283 ◽  
Author(s):  
R. Rathi ◽  
A. Honaramooz ◽  
W. Zeng ◽  
R. Turner ◽  
I. Dobrinski
Keyword(s):  
Body Temperature ◽  
Germ Cells ◽  
Core Body Temperature ◽  
Domestic Animals ◽  
Seminal Vesicles ◽  
Developmental Potential ◽  
Immunodeficient Mice ◽  
Core Body ◽  
Testis Tissue

In domestic animals, spermatogenic differentiation is blocked in abdominally retained testes exposed to core body temperature. It is not known if undifferentiated germ cells are retained in long-term cryptorchid equine testes, nor is it known whether any surviving germ cells retain their ability to progress through spermatogenesis. If functional germ cells do persist in equine abdominal testes, then the possibility exists that offspring could be derived even from bilaterally cryptorchid individuals. Previously, we reported an in vivo model where completion of spermatogenesis with production of spermatozoa capable of fertilization occurred in fragments of testicular tissue from immature mice, domestic animals, and monkeys grafted under the skin of immunodeficient mice. Therefore, spermatogenic development in testis tissue xenografts can serve as an in vivo assay system for the developmental potential of germ cells. The objective of this study was to investigate if cryptorchid horse testes that had been exposed to core body temperature for 1–3 years had retained developmentally competent germ cells. Small fragments of abdominally cryptorchid testis tissue (about 1 mm3) from three donor horses (1-, 2-, and 3-year-old Quarterhorse) were grafted under the back skin of castrated male immunodeficient mice (n = 8, 6, and 3 recipient mice, respectively). At the time of grafting, donor tissue did not contain differentiated germ cells. Histological examination of the testis xenografts was performed between 5 and 45 weeks post-transplantation. Weight of the seminal vesicles in the host mouse was recorded as an indicator of bioactive testosterone produced by the xenografts. By 28 weeks after grafting, pachytene spermatocytes were observed in xenografts from all cryptorchid donor testes. While haploid gametes would be expected to be present in xenografted testis tissue from descended equine testes by 35 weeks after grafting, spermatogenesis did not progress through meiosis in the cryptorchid grafts. In all recipient animals where spermatogenic differentiation occurred, the weight of the seminal vesicles in the castrated host mice was restored to pre-castration values, indicating that xenografts were capable of releasing biologically active testosterone. These results indicate that even after 3 years of exposure to core body temperature, equine cryptorchid testes contain germ cells capable of differentiation. It remains to be investigated if supplementation of exogenous gonadotropins might support post-meiotic differentiation of germ cells in cryptorchid equine testes xenografts. This work was supported by USDA 03-35203-13486.

scholarly journals Germ cell fate and seminiferous tubule development in bovine testis xenografts

Reproduction ◽  
2005 ◽  
Vol 130 (6) ◽  
pp. 923-929 ◽  
Author(s):  
Rahul Rathi ◽  
Ali Honaramooz ◽  
Wenxian Zeng ◽  
Stefan Schlatt ◽  
Ina Dobrinski
Keyword(s):  
Germ Cell ◽  
Cell Fate ◽  
Germ Cells ◽  
Cell Number ◽  
Sperm Production ◽  
Continuous Increase ◽  
Control Tissue ◽  
Low Efficiency ◽  
Pachytene Spermatocytes ◽  
Testis Tissue

Spermatogenesis can occur in testis tissue from immature bulls ectopically grafted into mouse hosts; however, efficiency of sperm production is lower than in other donor species. To elucidate a possible mechanism for the impaired spermatogenesis in bovine testis xenografts, germ cell fate and xenograft development were investigated at different time points and compared with testis tissue from age-matched calves as controls. Histologically, an initial decrease in germ cell number was noticed in xenografts recovered up to 2 months post-grafting without an increase in germ cell apoptosis. From 2 months onward, the number of germ cells increased. In contrast, a continuous increase in germ cell number was seen in control tissue. Pachytene spermatocytes were observed in some grafts before 4 months, whereas in the control tissue they were not present until 5 months of age. Beyond 4 months post-grafting spermatogenesis appeared to be arrested at the pachytene spermatocyte stage in most grafts. Elongated spermatids were observed between 6 and 8 months post-grafting, similar to the controls, albeit in much lower numbers. Lumen formation started earlier in grafts compared with controls and by 6 months post-grafting tubules with extensively dilated lumen were observed. A donor effect on efficiency of spermatogenesis was also observed. These results indicate that the low efficiency of sperm production in bovine xenografts is due to an initial deficit of germ cells and impaired meiotic and post-meiotic differentiation. The characterization of spermatogenic efficiency will provide the basis to understand the control of spermatogenesis in testis grafts.

Regeneration of testis tissue after ectopic implantation of porcine testis cell aggregates in mice: improved consistency of outcomes and in situ monitoring

2020 ◽  
Vol 32 (6) ◽  
pp. 594 ◽  
Author(s):  
Awang Hazmi Awang-Junaidi ◽  
Jaswant Singh ◽  
Ali Honaramooz
Keyword(s):  
De Novo ◽  
Ultrasound Biomicroscopy ◽  
In Situ Monitoring ◽  
Cell Aggregates ◽  
Tissue Development ◽  
Immunodeficient Mice ◽  
Non Invasive ◽  
Old Donor ◽  
Testis Tissue

Ectopic implantation of donor testis cell aggregates in recipient mice results in de novo formation or regeneration of testis tissue and, as such, provides a unique invivo model for the study of testis development. However, currently the results are inconsistent and the efficiency of the model remains low. This study was designed to: (1) examine several factors that can potentially improve the consistency and efficiency of this model and (2) explore the use of ultrasound biomicroscopy (UBM) for the non-invasive invivo evaluation of implants. Testis cell aggregates, containing ~40% gonocytes, from 1-week-old donor piglets were implanted under the back skin of immunodeficient mice through skin incisions using gel matrices or through subcutaneous injection without using gel matrices. The addition of gel matrices led to inconsistent tissue development; gelatin had the greatest development, followed by collagen, whereas agarose resulted in poor development. The results also depended on the implanted cell numbers since implants with 100×106 cells were larger than those with 50×106 cells. The injection approach for cell implantation was less invasive and resulted in more consistent and efficient testis tissue development. UBM provided promising results as a means of non-invasive monitoring of implants.

1 XENOGRAFTING OF ADULT MAMMALIAN TESTIS TISSUE

2007 ◽  
Vol 19 (1) ◽  
pp. 119
Author(s):  
L. Arregui ◽  
R. Rathi ◽  
W. Zeng ◽  
A. Honaramooz ◽  
M. Gomendio ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Germ Cell ◽  
Germ Cells ◽  
Sertoli Cells ◽  
Human Testis ◽  
Seminiferous Tubules ◽  
Donor Tissue ◽  
Germ Cell Differentiation ◽  
Sexually Mature ◽  
Testis Tissue

Testis tissue grafting presents an option for preservation of genetic material when sperm recovery is not possible. Grafting of testis tissue from sexually immature males to immunodeficient mice results in germ cell differentiation and production of fertilization-competent sperm from different mammalian species (Honaramooz et al. 2002 Nature 418, 778–781). However, the efficiency of testis tissue xenografting from adult donors has not been critically evaluated. Spermatogenesis was arrested at meiosis in grafts from mature horses (Rathi et al. 2006 Reproduction 131, 1091–1098) and hamsters (Schlatt et al. 2002 Reproduction 124, 339–346), and no germ cell differentiation occurred in xenografts of adult human testis tissue (Schlatt et al. 2006 Hum. Reprod. 21, 384–389). The objective of this study was to investigate survival and germ cell differentiation of testis xenografts from sexually mature donors of different species. Small fragments of testis tissue from 10 donor animals of 5 species were grafted under the back skin of immunodeficient, castrated male mice (n = 37, 2–6/donor). Donors were pig (8 months old), goat (18 months old and 4 years old) (n = 2), bull (3 years old), donkey (13 months old), and rhesus monkey (3, 6, 11, and 12 years old). At the time of grafting, donor tissue contained elongated spermatids, albeit to different degrees (>75% of seminiferous tubules in testis tissue from pig, goat, bull, and 6–12-year-old monkeys, and 33 or 66% of tubules in tissue from donkey or 3-year-old monkey, respectively). Grafts were recovered <12 weeks (n = 14 mice), 12–24 weeks (n = 16 mice), and >24 weeks (n = 7 mice) after grafting and classified histologically as completely degenerated (no tubules found), degenerated tubules (only hyalinized seminiferous tubules observed), or according to the most advanced type of germ cell present. Grafts from pig, goat, bull, and 6–12-year-old monkeys contained >60% degenerated tubules or were completely degenerated at all time points analyzed. In contrast, in grafts from the 3-year-old monkey, only 18% of tubules were degenerated, 14% contained Sertoli cells only, 64% contained meiotic, and 4% haploid germ cells at 24 weeks after grafting. Similarly, donkey testis grafts recovered 12–24 weeks after grafting contained <2% degenerated tubules, 46% of tubules had Sertoli cells only, 45% contained meiotic, and 7% haploid germ cells. These results show that survival and differentiation of germ cells in testis grafts from sexually mature mammalian donors is poor. However, better graft survival and maintenance of spermatogenesis occurred in donor tissue from donkey and 3-year-old monkey that were less mature at the time of grafting. Therefore, species and age-related differences appear to exist with regard to germ cell survival and differentiation in xenografts from adult donors. This work was supported by USDA/CSREES 03-35203-13486, NIH/NCRR 5-R01-RR17359-05, the Spanish Ministry of Education, and Science (BES-2004-4112).

309 THE SPERMATOGENIC CYCLE IN MAMMALIAN TESTIS XENOGRAFTS

2006 ◽  
Vol 18 (2) ◽  
pp. 262
Author(s):  
W. Zeng ◽  
G. F. Avelar ◽  
R. Rathi ◽  
L. R. Franca ◽  
I. Dobrinski
Keyword(s):  
Germ Cells ◽  
Stage I ◽  
Stage Ii ◽  
Brdu Incorporation ◽  
Seminiferous Tubules ◽  
Sperm Production ◽  
Porcine Tissue ◽  
Brdu Injection ◽  
Donor Species ◽  
Testis Tissue

Grafting of immature testis tissue from different mammalian donor species into mouse hosts results in production of spermatozoa from the donor species. Xenografting of testis tissue from rhesus monkeys, pigs, and sheep accelerates sperm production. To determine whether this shortened time to sperm production is due to the reduced spermatogenic cycle length, we applied bromodeoxyuridine (BrdU) incorporation to analyze the spermatogenic cycle in porcine and ovine testis xenografts. Testes from 1-2-week-old Yorkshire cross pigs and 1-week-old Suffolk sheep were cut into small fragments (approximately 1 � 1 � 2 mm) and eight fragments were grafted under the back skin of each castrated male immunodeficient NCR nude recipient mouse (n = 7 for pig, n = 5 for sheep). Mice were given BrdU (100 mg/kg i.p.) at 7 months (porcine tissue) or 6 months (ovine tissue) post-transplantation. Mice carrying porcine tissue were sacrificed 1 h, 9 days or 18 days after BrdU injection. Mice with ovine testicular tissue were sacrificed 1 h, 11 days or 22 days after BrdU injection. Analysis time points were chosen based on the reported length of the spermatogenic cycle in pigs and sheep (approximately 9 days and 11 days, respectively). All eight stages of the spermatogenic cycle were analyzed to identify the most advanced germ cells labeled in each time period after BrdU injection. All seminiferous tubules containing full spermatogenesis were analyzed. Histologically, 51.8% (range 7 to 98%, n = 2040 tubules) of seminiferous tubules from porcine grafts, and 64.4% (range 2 to 92%, n = 2903 tubules) of seminiferous tubules from ovine grafts presented complete spermatogenesis. In porcine grafts, the most advanced germ cells labeled 1 h after BrdU injection were primary spermatocytes in pre-leptotene/leptotene at stage I of the spermatogenic cycle. At 9 days and 18 days after injection, the most advanced labeled germ cells were primary spermatocytes at pachytene at stage I and elongating spermatids at late stage II, respectively. In ovine grafts, the most advanced labeled germ cells at 1 h, 11 days and 22 days were pre-leptotene/leptotene at stage II, primary spermatocytes at the pachytene at stage I and elongating spermatids at stage II, respectively. These results indicate that each spermatogenic cycle in porcine and ovine testis xenografts lasts around 9 days and 11 days, respectively. Therefore, the length of the spermatogenic cycle is conserved in porcine and ovine testis xenografts and shortened time to sperm production is likely due to accelerated maturation of the testicular somatic components, such as Sertoli cells. This work was supported by NIH R01 RR17359-01.

scholarly journals Gonadal status of male recipient mice influences germ cell development in immature buffalo testis tissue xenograft

Reproduction ◽  
2012 ◽  
Vol 143 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Niranjan Reddy ◽  
Ranjeet Singh Mahla ◽  
Revanth Thathi ◽  
Sanjay Kumar Suman ◽  
Jedy Jose ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Germ Cell ◽  
Germ Cells ◽  
Serum Testosterone ◽  
Intact Mouse ◽  
Germ Cell Differentiation ◽  
Pachytene Spermatocytes ◽  
Gonadal Status ◽  
Tubule Diameter ◽  
Testis Tissue

Growth and development of immature testis xenograft from various domestic mammals has been shown in mouse recipients; however, buffalo testis xenografts have not been reported to date. In this study, small fragments of testis tissue from 8-week-old buffalo calves were implanted subcutaneously onto the back of immunodeficient male mouse recipients, which were either castrated or left intact (non-castrated). The xenografts were retrieved and analyzed 12 and 24 weeks later. The grafted tissue survived and grew in both types of recipient with a significant increase in weight and seminiferous tubule diameter. Recovery of grafts from intact recipients 24 weeks post-grafting was significantly lower than that from the castrated recipients. Seminal vesicle indices and serum testosterone levels were lower in castrated recipients at both collection time points in comparison to the intact recipients and non-grafted intact mouse controls. Pachytene spermatocytes were the most advanced germ cells observed in grafts recovered from castrated recipients 24 weeks post-grafting. Complete spermatogenesis, as indicated by the presence of elongated spermatids, was present only in grafts from intact recipients collected 24 weeks post-grafting. However, significant number of germ cells with DNA damage was also detected in these grafts as indicated by TUNEL assay. The complete germ cell differentiation in xenografts from intact recipients may be attributed to efficient Sertoli cell maturation. These results suggest that germ cell differentiation in buffalo testis xenograft can be completed by altering the recipient gonadal status.

A distinct cyclin A is expressed in germ cells in the mouse

Development ◽  
1996 ◽  
Vol 122 (1) ◽  
pp. 53-64 ◽  
Author(s):  
C. Sweeney ◽  
M. Murphy ◽  
M. Kubelka ◽  
S.E. Ravnik ◽  
C.F. Hawkins ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Germ Cells ◽  
Cyclin A ◽  
Cyclin A1 ◽  
Late Pachytene ◽  
Sequence Identity ◽  
Somatic Tissues ◽  
Cyclin A2 ◽  
Pachytene Spermatocytes ◽  
Metaphase Ii Oocytes

In this paper, the existence of two A-type cyclins in the mouse is demonstrated. In the adult mouse, the expression of cyclin A1, which has greatest sequence identity with Xenopus cyclin A1, is restricted to germ cells. In contrast cyclin A2, which has greatest sequence identity with human cyclin A and Xenopus cyclin A2, is expressed in all tissues analysed. In order to explore the function of cyclin A1 in germ cells, its expression during the meiotic cell cycle and its associated kinase subunits have been characterised in the testis. The levels of cyclin A1 mRNA rise dramatically in late pachytene spermatocytes and become undetectable soon after completion of the meiotic divisions; thus its expression is cell cycle regulated. In lysates of germ cells from adult testes, cyclin A1 is present in p13suc1 precipitates, and cyclin A1 immunoprecipitates possess histone H1 kinase activity. Three kinase partners of cyclin A1 were identified: p34cdc2, a polypeptide of 39 × 10(3) M(r) that is related to p33cdk2 and, in lesser quantities, p33cdk2. Cyclin A1 was also detected in oocytes; in metaphase I and metaphase II oocytes, a proportion of the cyclin A1 colocalises with the spindle, possibly suggestive of a functional interaction. These data indicate that mammalian germ cells contain cyclin A1-dependent kinases that either act as a substitute for, or in addition to, the cyclin A2-dependent kinases characterised in somatic tissues.

scholarly journals Vascular endothelial growth factor regulates germ cell survival during establishment of spermatogenesis in the bovine testis

Reproduction ◽  
2009 ◽  
Vol 138 (4) ◽  
pp. 667-677 ◽  
Author(s):  
Kyle C Caires ◽  
Jeanene de Avila ◽  
Derek J McLean
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Growth Factor ◽  
Germ Cell ◽  
Cell Survival ◽  
Germ Cells ◽  
Pcr Analysis ◽  
Vascular Endothelial ◽  
Endothelial Growth Factor ◽  
Testis Tissue

Vascular endothelial growth factor-A (VEGFA) is a hypoxia-inducible peptide essential for angiogenesis and targets nonvascular cells in a variety of tissues and cell types. The objective of the current study was to determine the function of VEGF during testis development in bulls. We used an explant tissue culture and treatment approach to test the hypothesis that VEGFA-164 could regulate the biological activity of bovine germ cells. We demonstrate that VEGFA, KDR, and FLT1 proteins are expressed in germ and somatic cells in the bovine testis. Treatment of bovine testis tissue with VEGFA in vitro resulted in significantly more germ cells following 5 days of culture when compared with controls. Quantitative real-time RT-PCR analysis determined that VEGF treatment stimulated an intracellular response that prevents germ cell death in bovine testis tissue explants, as indicated by increased expression of BCL2 relative to BAX and decreased expression of BNIP3 at 3, 6, and 24 h during culture. Blocking VEGF activity in vitro using antisera against KDR and VEGF significantly reduced the number of germ cells in VEGF-treated testis tissue to control levels at 120 h. Testis grafting provided in vivo evidence that bovine testis tissue treated with VEGFA for 5 days in culture contained significantly more differentiating germ cells compared with controls. These findings support the conclusion that VEGF supports germ cell survival and sperm production in bulls.

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