Stickland N C, Crook A R, Sutton C M
Department of Veterinary Basic Sciences, Royal Veterinary College, London, UK.
Acta Anat (Basel). 1994;151(4):245-9. doi: 10.1159/000147670.
The Snell dwarf mouse exhibits impaired growth of the anterior pituitary resulting in reduced levels of growth hormone and thyroid stimulating hormone. Ten dwarf mice and 10 phenotypically normal littermates were killed at 33 days of age. M. biceps brachii (a predominantly fast muscle) and m. soleus (a relatively slow muscle) were removed from each animal and complete frozen transverse sections obtained. Serial sections were reacted for various enzyme activities in order to identify muscle fibre types. There was no difference in the total number of muscle fibres in m. biceps brachii but a small difference in m. soleus between normal and dwarf mice. There were marked differences in the size of all fibre types between normal and dwarf mice with the largest differences in m. soleus. The percentage of slow oxidative fibres was similar (about 32%) in both groups of mice for m. soleus but there was a marked difference for this fibre type in m. biceps brachii being about 1.5% in normal mice and 8.0% in dwarf mice. This may be related to a difference in levels of thyroid hormone. Nuclear density was very significantly greater in dwarf muscles although total nuclear numbers were less than in normal muscles. These differences are most likely due to growth hormone levels. Differences in nuclear content were much greater in m. soleus than in m. biceps brachii.
斯内尔侏儒小鼠表现出垂体前叶生长受损，导致生长激素和促甲状腺激素水平降低。10只侏儒小鼠和10只表型正常的同窝小鼠在33日龄时被处死。从每只动物身上取下肱二头肌（主要是快肌）和比目鱼肌（相对慢肌），并获得完整的冷冻横切片。连续切片用于检测各种酶活性，以识别肌纤维类型。正常小鼠和侏儒小鼠的肱二头肌肌纤维总数没有差异，但比目鱼肌存在微小差异。正常小鼠和侏儒小鼠之间所有纤维类型的大小存在显著差异，比目鱼肌的差异最大。两组小鼠比目鱼肌的慢氧化纤维百分比相似（约32%），但肱二头肌中这种纤维类型存在显著差异，正常小鼠约为1.5%，侏儒小鼠为8.0%。这可能与甲状腺激素水平的差异有关。侏儒肌肉中的核密度非常显著地高于正常肌肉，尽管核总数比正常肌肉少。这些差异很可能是由于生长激素水平不同。比目鱼肌的核含量差异比肱二头肌大得多。
