Siegford Janice M, Hadi Mansouri S, Ulibarri Catherine
Department of Veterinary, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA.
Anat Rec A Discov Mol Cell Evol Biol. 2003 Nov;275(1):997-1008. doi: 10.1002/ar.a.10118.
The spinal nucleus of the bulbocavernosus (SNB) of Mongolian gerbils (Meriones unguiculatus) becomes sexually dimorphic during postnatal life, rather than prenatally as in rats. We therefore examined the early postnatal ontogeny of Mongolian gerbils, focusing on growth, serum testosterone (T) levels, and the sexually dimorphic perineal musculature innervated by the SNB. Serum T levels were higher in males than in females from birth through adulthood, with several early postnatal peaks and a large increase in T occurring during puberty in males. The SNB target muscles-the bulbocavernosus (BC) and levator ani (LA)-were present in both sexes on postnatal day 1 (PND1). Cross-sectional areas of BC fibers in males increased with age, and concurrently the myofibers of the BC became more fully developed and organized. In PND10 female pups, the BC muscle was virtually absent, while the LA muscle remained (although it was reduced in size). Postnatal treatment of female gerbils with androgen caused the BC muscle to remain and the LA muscle to become larger by PND10. Sexual dimorphism of the SNB develops differently in gerbils compared to other species, although its target muscles appear to respond to androgen in a manner similar to that in rats.
蒙古沙鼠（长爪沙鼠）球海绵体肌核（SNB）在出生后而非像大鼠那样在出生前发育为两性异形。因此，我们研究了蒙古沙鼠出生后的早期个体发育，重点关注生长、血清睾酮（T）水平以及由SNB支配的两性异形会阴肌肉组织。从出生到成年，雄性血清T水平高于雌性，出生后早期有几个峰值，雄性在青春期T水平大幅升高。SNB的靶肌肉——球海绵体肌（BC）和肛提肌（LA）在出生后第1天（PND1）时两性均存在。雄性BC纤维的横截面积随年龄增加，同时BC的肌纤维变得更加成熟和有序。在PND10的雌性幼崽中，BC肌肉几乎不存在，而LA肌肉仍然存在（尽管尺寸减小）。出生后用雄激素处理雌性沙鼠会使BC肌肉保留，并且到PND10时LA肌肉变大。与其他物种相比，沙鼠中SNB的两性异形发育有所不同，尽管其靶肌肉对雄激素的反应方式与大鼠相似。
