van Beek M E, Meistrich M L
Department of Experimental Radiotherapy, University of Texas M.D. Anderson Cancer Center, Houston 77030.
Biol Reprod. 1991 Aug;45(2):235-44. doi: 10.1095/biolreprod45.2.235.
Optimal conditions for obtaining stage-synchronization of the seminiferous epithelium were investigated. In this study, 147 rats were subjected to protocols in which vitamin A deficiency was induced by feeding a diet without retinol (R-ol) or retinoic acid (RA), followed by maintenance on a diet containing RA and supplementation of R-ol by injection and diet. An acceptable degree of stage synchronization and recovery of the seminiferous epithelium was observed in 90 (61%) of the 147 rats. The effects on synchrony of variations in the protocol, including the degree of deficiency before RA maintenance, the dose and duration of RA maintenance, and the manner of injection of R-ol, were tested. Initiation of maintenance on RA when a medium degree of deficiency was achieved (4-12 g of weight loss, 3-6 days without growth) resulted in a more reliable (80% of the rats) induction of synchrony than did initiation of maintenance on RA at either a less (70% synchronized rats) or more severe (50-60% synchronized rats) deficiency. Maintenance on food containing 10 mg/kg RA gave better and more reliable synchrony (70%) than maintenance on food containing 5 mg/kg RA (less than 40%). Although the duration of this maintenance did not influence the degree of synchrony, the reliability was lower when maintenance was continued for a month or more (54%). During the interval from 33 to 128 days after resupplementation, the degree of synchronization decreased, as did the predictability of the stages, while the restoration of spermatogenesis increased. Linear regression, performed on the location of the median point of synchronization, indicated that spermatogenesis progressed at a rate of 12.4 days per cycle. The median stage of synchronization, predicted by this regression line, differed by an average of 8% of the cycle from the actual location in individual rats. Extrapolation of the regression line indicated that spermatogenesis was reinitiated in mid-to-late stage VII.
研究了获得生精上皮阶段同步化的最佳条件。在本研究中，147只大鼠接受了相关实验方案，即通过喂食不含视黄醇（R-ol）或视黄酸（RA）的饮食诱导维生素A缺乏，随后维持在含RA的饮食上，并通过注射和饮食补充R-ol。在147只大鼠中，90只（61%）观察到了可接受程度的阶段同步化和生精上皮的恢复。测试了实验方案变化对同步化的影响，包括RA维持前的缺乏程度、RA维持的剂量和持续时间以及R-ol的注射方式。当达到中度缺乏（体重减轻4 - 12克，3 - 6天无生长）时开始用RA维持，比在较轻（70%同步化大鼠）或更严重（50 - 60%同步化大鼠）缺乏时开始用RA维持能产生更可靠（80%的大鼠）的同步化诱导。在含10 mg/kg RA的食物上维持比在含5 mg/kg RA的食物上维持能产生更好且更可靠的同步化（70%）（低于40%）。尽管这种维持的持续时间不影响同步化程度，但持续维持一个月或更长时间时可靠性较低（54%）。在重新补充后33至128天的间隔期内，同步化程度下降，阶段的可预测性也下降，而生精作用的恢复增加。对同步化中点位置进行线性回归分析表明，生精作用以每个周期12.4天的速度进行。由该回归线预测的同步化中位阶段与个别大鼠的实际位置平均相差周期的8%。回归线的外推表明生精作用在第VII阶段中后期重新开始。
