Transforming growth factor beta-1 decreases the yield of the second meiotic division of rat pachytene spermatocytes in vitro.
BACKGROUND
TGF beta and its receptors are present in both germ cells and somatic cells of the male gonad. However, knock-out strategies for studying spermatogenesis regulation by TGF beta have been disappointing since TGF beta-or TGF beta receptor-null mice do not survive longer than a few weeks.


METHODS
In the present study, we addressed the role of TGF beta-1 on the completion of meiosis by rat pachytene spermatocytes (PS) cocultured with Sertoli cells. Identification and counting of meiotic cells were performed by cytology and cytometry.


RESULTS
Under our culture conditions, some PS differentiated into round spermatids (RS). When TGF beta-1 was added to the culture medium, neither the number of PS or of secondary spermatocytes nor the half-life of RS was modified by the factor. By contrast, the number of RS and the amount of TP1 mRNA were lower in TGF beta-1-treated cultures than in control cultures. Very few metaphase I cells were ever observed both in control and TGF beta-1-treated wells. Higher numbers of metaphase II were present and their number was enhanced by TGF beta-1 treatment. A TGF beta-like bioactivity was detected in control culture media, the concentration of which increased with the time of culture.


CONCLUSIONS
These results indicate that TGF beta-1 did not change greatly, if any, the yield of the first meiotic division but likely enhanced a bottleneck at the level of metaphase II. Taken together, our results suggest strongly that TGF beta participates in an auto/paracrine pathway of regulation of the meiotic differentiation of rat spermatocytes.
Damestoy
Anne
A
INSERM U418, Université Claude-Bernard Lyon 1, 29 rue soeur Bouvier, 69322 Lyon cedex 05, France. damestoy@lyon.inserm.fr
Perrard
Marie-Hélène
MH
Vigier
Michèle
M
Sabido
Odile
O
Durand
Philippe
P
D000818:Animals; D001973:Bromodeoxyuridine / Q000032:analysis; D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D018920:Coculture Techniques; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D008297:Male; D049471:Pachytene Stage / Q000502:physiology*; D011003:Ploidies; D051381:Rats; D012708:Sertoli Cells / Q000166:cytology; D013090:Spermatocytes / Q000166:cytology* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000502:physiology*; D053773:Transforming Growth Factor beta1
D050759:Cyclin-Dependent Kinase Inhibitor p21; C508962:Tgfb1 protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D001973:Bromodeoxyuridine