Meisami E, Najafi A, Timiras P S
Division of Developmental and Cell Biology, University of California, Berkeley 94720.
Cell Tissue Res. 1994 Mar;275(3):503-11. doi: 10.1007/BF00318819.
Testicular weight and DNA content were markedly reduced (63 and 69%) in weanling Long-Evans rat pups rendered hypothyroid from birth by administration of propylthiouracil (PTU), a reversible goitrogen. These growth deficits worsened to > 80% by continuing hypothyroidism beyond weaning, to days 50 and 90. Recovery of thyroid function, brought about by discontinuing PTU at weaning, resulted in a paradoxical stimulation of testis growth, amounting to increased weight (40%), DNA content (60%) and size by 90 days, compared to age-matched controls. In the 25-day or older hypothyroid rats, testicular structure was immature and spermatogenesis markedly delayed, as evident by closed lumen and significantly reduced diameter of seminiferous tubules (38%), thickness of germinal layer (70%), and number of primary spermatocytes (86%), compared to control. Hypothyroidism did not alter the number of tubules per testis cross section. In the 90-day recovery rats, numbers of seminiferous tubules were unchanged but tubular diameter was significantly (20%) larger than in controls and spermatogenesis appeared very active as indicated by significantly increased germinal layer thickness (22%) and total number and density of primary spermatocytes (55% and 40%). The results show that although postnatal hypothyroidism is deleterious for testicular growth and spermatogenesis, recovery from this condition leads to enhanced seminiferous tubular growth and spermatogenesis.
通过给予丙硫氧嘧啶（PTU，一种可逆性致甲状腺肿物质）使新生的Long-Evans断奶大鼠幼崽从出生起就甲状腺功能减退，其睾丸重量和DNA含量显著降低（分别为63%和69%）。如果断奶后持续甲状腺功能减退至50天和90天，这些生长缺陷会恶化至超过80%。断奶时停止给予PTU使甲状腺功能恢复，结果却反常地刺激了睾丸生长，到90天时，与年龄匹配的对照组相比，睾丸重量增加了40%，DNA含量增加了60%，大小也有所增加。在25日龄及以上的甲状腺功能减退大鼠中，睾丸结构不成熟，精子发生明显延迟，与对照组相比，可见管腔闭合、生精小管直径显著减小（38%）、生发层厚度显著减小（70%）以及初级精母细胞数量显著减少（86%）。甲状腺功能减退并未改变每个睾丸横截面上的小管数量。在90日龄的恢复组大鼠中，生精小管数量未变，但管腔直径比对照组显著增大（20%），并且精子发生看起来非常活跃，表现为生发层厚度显著增加（22%）以及初级精母细胞总数和密度显著增加（分别为55%和40%）。结果表明，虽然出生后甲状腺功能减退对睾丸生长和精子发生有害，但从这种状态恢复会导致生精小管生长和精子发生增强。
