Xie Q, Mackay S, Ullmann S L, Gilmore D P, Payne A P
Institute of Biomedical and Life Sciences, University of Glasgow, Scotland, UK.
J Anat. 1996 Oct;189 ( Pt 2)(Pt 2):393-406.
Testis development in the grey short-tailed opossum, Monodelphis domestica, was investigated by light and electron microscopy in 180 animals. On the day of birth, half the karyotyped males were found to have histologically differentiated testes. By day (d) 1 testicular cords were clearly distinguished in all XY gonads and the tunica albuginea was fully developed. At this stage the large and pale primordial germ cells could be differentiated from dark pre-Sertoli cells. From d 3 the testis became progressively rounded and testicular cords were surrounded by peritubular cells. Leydig cells were then distinguishable by the expected ultrastructural features of steroidogenically active cells, showing abundant vesicles of SER, extensive mitochondria with tubular cristae and numerous lipid inclusions. Subsequently these cells formed clusters and were surrounded by envelope cells until wk 12. Testes were located in the abdomen, attached to the large mesonephroi, until d 24 after birth when they began their descent to the scrotal sac. From 7 wk the interstitial tissue became less cellular. At the prepubertal stage (12 wk), the seminiferous tubules lacked lumina. Leydig cell cytoplasm was electron-dense with increased amounts of SER forming parallel profiles. By 4 mo (pubertal stage), seminiferous tubules were patent and various spermatogenic stages, including spermatozoa, were seen for the first time. Leydig cells then greatly outnumbered other interstitial tissue cells and were closely-packed around blood vessels but no longer clustered by envelope cells; their SER was very highly organised into masses of parallel arrays and lipid inclusions were reduced. In the adult (1 y) Leydig cells reached their greatest size; their morphological features resembled those seen at 4 mo except that lipid inclusions were sparse. In ageing Leydig cells (2-3 y), large amounts of SER were present but disorganised.
通过光学显微镜和电子显微镜对180只灰短尾负鼠（Monodelphis domestica）的睾丸发育进行了研究。出生当天，经核型分析的雄性中有一半被发现睾丸在组织学上已分化。到第1天，所有XY性腺中都能清楚地分辨出睾丸索，白膜也已完全发育。在此阶段，大而浅色的原始生殖细胞可与深色的前支持细胞区分开来。从第3天开始，睾丸逐渐变圆，睾丸索被睾丸周细胞包围。此时，间质细胞可通过类固醇生成活性细胞预期的超微结构特征加以区分，表现为丰富的滑面内质网囊泡、具有管状嵴的广泛线粒体以及大量脂质包涵体。随后，这些细胞形成簇，并被包膜细胞包围，直至第12周。睾丸位于腹部，附着于大的中肾，直到出生后第24天开始下降至阴囊。从第7周开始，间质组织细胞减少。在青春期前阶段（12周），生精小管无管腔。间质细胞的细胞质电子密度增加，滑面内质网数量增多，形成平行排列。到4个月（青春期阶段）时，生精小管有管腔，首次见到包括精子在内的各种生精阶段。此时，间质细胞的数量大大超过其他间质组织细胞，紧密排列在血管周围，但不再被包膜细胞聚集在一起；它们的滑面内质网高度有序地排列成平行阵列，脂质包涵体减少。在成年（1岁）时，间质细胞达到最大尺寸；其形态特征与4个月时相似，只是脂质包涵体稀少。在衰老的间质细胞（2 - 3岁）中，存在大量滑面内质网，但排列紊乱。
