Hirano N, Shiino M
Department of Anatomy, Wakayama Medical College, Japan.
Tissue Cell. 1997 Jun;29(3):375-81. doi: 10.1016/s0040-8166(97)80013-4.
In order to examine the significance of small round and large granules in the thyrogonadotrophs of the musk shrew, we investigated the differences of numbers, distribution patterns and/or immunoreactivities of the large granules in the thyrogonadotrophs among the newborn, infant and adult musk shrews. As a result, we observed that the thyrogonadotrophs exist in newborn musk shrew, but the large granules were few in number and immunoreactivity on the granules was weak. The ratio of the number of large granule-containing cells to all LH beta positive cells was very low (6.2%) in newborn musk shrew, but high (98.2%) in adult male animals. We assume that thyrogonadotrophs of newborn shrews may not yet synthesize active beta-subunits, that the synthesis of beta-subunits is gradually increased with aging, and excessive products of beta-subunits may be stored in the large granules. It is known that female musk shrews are induced ovulators; therefore, we investigated morphological changes in the large and small granules in the thyrogonadotrophs at the LH surge which occurs after mating. We observed that the small granules were markedly decreased in number, or had almost vanished, 2 h after mating, but that the large granules still remained. Consequently, we assume that the large granules may be storage sites of excessive products of beta-subunits in older animals. On the other hand, small granules (release type granules) may be exhausted by release of a large quantity of gonadotrophin 2 h after mating, and this acute exhaustion of small granules may induce a sharp depression of the LH surge.
为了研究麝鼩促甲状腺性腺激素细胞中小圆形颗粒和大颗粒的意义，我们调查了新生、幼年和成年麝鼩促甲状腺性腺激素细胞中大颗粒在数量、分布模式和/或免疫反应性方面的差异。结果，我们观察到新生麝鼩中存在促甲状腺性腺激素细胞，但大颗粒数量较少，颗粒上的免疫反应性较弱。新生麝鼩中含大颗粒的细胞数量与所有促黄体生成素β阳性细胞数量的比例非常低（6.2%），但成年雄性动物中该比例较高（98.2%）。我们推测新生麝鼩的促甲状腺性腺激素细胞可能尚未合成活性β亚基，β亚基的合成随年龄增长逐渐增加，β亚基的过量产物可能储存在大颗粒中。已知雌性麝鼩是诱导排卵者；因此，我们研究了交配后促黄体生成素高峰时促甲状腺性腺激素细胞中大颗粒和小颗粒的形态变化。我们观察到交配后2小时，小颗粒数量明显减少或几乎消失，但大颗粒仍然存在。因此，我们推测大颗粒可能是老年动物中β亚基过量产物的储存部位。另一方面，小颗粒（释放型颗粒）可能在交配后2小时因大量促性腺激素的释放而耗尽，小颗粒的这种急性耗尽可能导致促黄体生成素高峰急剧下降。
