Female birds have a special type of bone , called a medullary bone , that grows in their limbs when they are laying eggs , forming a layer inside the hard outer bone 骨髓骨富含形成卵壳的钙元素。当雌鸟进入孵卵期时，骨髓骨开始在翼处发育，并在坚硬的翼骨外层下形成一层。
2.
The follicle cells taked part in the synthesis of yolk precursor , and the yolk precursor were transported into oocyte by pinocytosis and fusion . after follicle cells secreting egg shells , oogenesis completed 在帮助卵母细胞沉积完卵黄后，滤泡细胞还分泌卵壳蛋白，形成卵壳之后退化消失
3.
The brine shrimp he was prepared and purified by 67 % ammonium sulfate precipitation , deae - sepharose fast flow ion - exchange chromatography , and sephacryl column gel - filtration , and its biochemical and enzymological properties were identified in this study . it was found that the deduced molecular weight of he in sds - page is about 98 . 5 kda , and its proteolytic activity was optimized at ph of 7 . 5 - 8 . 5 and at temperature of 40 , respectively 我们利用67硫酸铵沉淀、 deae - sepharosefastflow阴离子交换柱层析和sephacryl凝胶过滤柱层析，并以酪蛋白为其蛋白酶水解活性的检测底物、以卵膜为其卵壳裂解活性的特异性底物，从卤虫胚胎孵化液中分离纯化出了卤虫的孵化酶分子，其在sds - page电泳中的分子量约为98 . 5kda 。
