Barthold J S, Mahler H R, Newton B W
Department of Urology, University of Arkansas for Medical Sciences, Little Rock.
J Urol. 1994 Dec;152(6 Pt 2):2280-6. doi: 10.1016/s0022-5347(17)31658-0.
Androgens may control rat testicular descent via effects on the genitofemoral nerve or cranial gonadal ligaments. Androgen-mediated release of calcitonin gene-related peptide from the genito-femoral nerve (whose motoneuron cell bodies reside in the sexually dimorphic cremaster nucleus) may stimulate cremaster sac formation and testicular descent. Alternatively, androgens may cause regression of cranial gonadal ligaments and thereby allow the testes to descend. To evaluate these theories testicular position, and the cremaster sac and nucleus were studied in Tfm (androgen insensitive) rats. Testes were abdominal, inguinal and scrotal in 20%, 67% and 13% of Tfm male rats, respectively, and cranial ligaments were present in all cases. Mean cremaster nucleus motoneuron number was lower in female rats (70 +/- 14) but not significantly different between normal male (256 +/- 44) and Tfm male (231 +/- 42) rats, and it correlated poorly with testicular position. Calcitonin gene-related peptide immunoreactivity was rarely observed in cremaster motoneurons. These data suggest that the cremaster nucleus is not androgen-dependent, calcitonin gene-related peptide release from cremaster motoneurons is not the likely mechanism of testicular descent and persistent cranial ligaments may cause cryptorchidism in the Tfm rat.
雄激素可能通过对生殖股神经或颅侧性腺韧带的作用来控制大鼠睾丸下降。雄激素介导的降钙素基因相关肽从生殖股神经（其运动神经元胞体位于性别二态性的提睾肌核）释放，可能刺激提睾肌囊形成和睾丸下降。或者，雄激素可能导致颅侧性腺韧带退化，从而使睾丸下降。为了评估这些理论，我们对雄激素不敏感（Tfm）大鼠的睾丸位置、提睾肌囊和提睾肌核进行了研究。在Tfm雄性大鼠中，分别有20%、67%和13%的睾丸位于腹部、腹股沟和阴囊，且所有病例均存在颅侧韧带。雌性大鼠提睾肌核运动神经元的平均数量较少（70±14），但正常雄性大鼠（256±44）和Tfm雄性大鼠（231±42）之间无显著差异，且与睾丸位置的相关性较差。在提睾肌运动神经元中很少观察到降钙素基因相关肽免疫反应性。这些数据表明，提睾肌核不依赖雄激素，提睾肌运动神经元释放降钙素基因相关肽不太可能是睾丸下降的机制，而持续存在的颅侧韧带可能导致Tfm大鼠隐睾。
