什么是性早熟？

性早熟，在医学上指儿童的性腺(即男性的睾丸、女性的卵巢功能)过早发育，引起生殖器官发育提前和出现第二性征：医学上性早熟的界定年龄是女孩在8岁以前或男孩在10岁以前。由于现代生活水平的不断提高，儿童进入青春期以及达到性成熟的年龄，在世界范围内有逐渐提前的趋势。     

The discovery of whole-plant fossil cycad from the Upper Triassic in western Liaoning and its significance

A recently discovered megafossil of whole plant cycad is briefly reported here. The specimen is collected from the Yangcaogou Formation （Upper Triassic） in Changheying, Beipiao, Liaoning. The whole plant is preserved intact on a sandstone slab, 89 cm long and 130 cm wide, including leaves up to 82 cm long and a male cone physically attached to the stem apex. Analysis on the morphology, arrangement and venation of leaf and pinna, male cone and its relationship with other parts indicates that the fossil is closely related to living Zamiaceae in Cycadales. This cycad fossil is hitherto most completely preserved cycad specimen including both vegetative and reproductive organs. Its discovery contributes much to our understanding of the morphology and evolution of cycads, palaeoclimate as well as palaeoenvironment.     

白唇鹿生殖器官解剖特征的研究

为了探讨白唇鹿的生殖生理,保护和增殖这一珍贵资源动物,本文对其生殖器官进行了解剖学研究。发现雄性睾丸之纵轴与体轴成直角位置,实质棕黄色,小叶不明显;精囊腺表面光滑而发达,前列腺和尿道球腺短小;阴茎呈圆柱状,龟头前端有4—5个裂口,膨大时呈莲花瓣状。雌性卵巢为偏平的椭圆形;子宫角为绵羊角状,基部融为一体,每侧角有4—5个长椭圆形的肉阜排成一列,怀孕时可随胎儿的发育而增长,子宫体短小,子宫颈坚实,阴道宽大.白唇鹿的以上特征与其它动物有着明显差.     

爬管藻属生殖器官形态发育的研究

本文报道了柔细爬管藻(Herposiphonia delicatula)四分孢子囊、精子囊群枝、果胞系和囊果的发育以及二列爬管藻(H.subdistichia)叶状爬管藻(H.fissidentoides)囊果被的结构。本研究材料采自福建省晋江县永宁海区。采用连续石蜡切片及压片进行观察。结果表明,柔细爬管藻生殖器官的发育与松节藻科中其它属的种类大致相同,但其囊果被的结构和育性毛丝体的形态与其它属的种类有所差异,其成熟囊果的囊果被是单层的,二列爬管藻和叶状爬管藻囊果被也是单层的。因此,囊果被的层数和育性毛丝体的形态,可作为松节藻科系统分类的重要依据。