Kinoue T
Department of Hygiene/Space Medicine, Nihon University School of Medicine.
Nichidai Igaku Zasshi. 1996;55(10):549-59.
A tail-suspension model to simulate weightlessness is widely used for studies on physiological changes not only of the musculoskeletal system but also of the cardiovascular system. In the present study, we applied this model to investigate whether or not it is possible for male spermatogenesis to occur, and for female rats to maintain pregnancy in this model. Two male rats were suspended with the right inguinal canal ligated loosely for 14 days, and female rats were suspended after copulation (the day when spermatozoa were identified on a smear from the female rat, was referred to as Day 0 for her in this paper). The duration of suspension was chosen dependent upon events to be confirmed during the course of pregnancy. To demonstrate the effects of suspension on implantation, the first and second groups consisted respectively of non-suspended rats penetrated at the base of the tail in the same way as suspended rats, and rats suspended during the former half of pregnancy (Days 0-12, and 0-14). The third group consisted of rats suspended during the latter half (Days 10-20, 10-21, 10-26, and 10-28), and in the final group a rat suspended throughout pregnancy (Days 0-22) was placed. Histological analysis of the male rat testes showed that the testes on the ligated side were scarcely impaired, while the others became degenerated presenting similar appearances of cryptorchidism. The levels of serum testosterone were lower than the control values. As for the female rats, one animal in the final group was successful in parturition, and implantation appeared to be delayed in the second group. A tail-suspended rat, if it is acclimatized to its environment, could succeed in parturition. By employing this model, we can certainly elucidate some new aspects of mammalian reproduction in space.
一种模拟失重的尾部悬吊模型不仅被广泛用于研究肌肉骨骼系统的生理变化，还用于研究心血管系统的生理变化。在本研究中，我们应用该模型来研究雄性大鼠在该模型中是否可能发生精子发生，以及雌性大鼠在该模型中是否能够维持妊娠。将两只雄性大鼠的右腹股沟管松散结扎后悬吊14天，雌性大鼠在交配后进行悬吊（在雌性大鼠涂片上发现精子的当天，在本文中对其而言称为第0天）。悬吊的持续时间根据妊娠过程中要确认的事件来选择。为了证明悬吊对着床的影响，第一组和第二组分别由以与悬吊大鼠相同的方式在尾部基部穿刺的非悬吊大鼠，以及在妊娠前半期（第0 - 12天和0 - 14天）悬吊的大鼠组成。第三组由在妊娠后半期（第10 - 20天、10 - 21天、10 - 26天和10 - 28天）悬吊的大鼠组成，在最后一组中放置了一只在整个妊娠期间（第0 - 22天）悬吊的大鼠。对雄性大鼠睾丸的组织学分析表明，结扎侧的睾丸几乎未受损害，而其他睾丸则发生退化，呈现出类似隐睾的外观。血清睾酮水平低于对照值。至于雌性大鼠，最后一组中的一只动物成功分娩，第二组中着床似乎延迟。一只经过环境适应的尾部悬吊大鼠能够成功分娩。通过采用该模型，我们肯定能够阐明哺乳动物在太空中繁殖的一些新方面。
