排序方式: 共有2条查询结果,搜索用时 0 毫秒
1
1.
大熊猫与金黄地鼠体外异种受精的研究 总被引:4,自引:4,他引:0
在大熊猫精子与地鼠卵的体外异种受精中,发现大熊猫精子穿入地鼠卵后可以激活受精卵产生极区,释放第二极体,受精卵内雌性原核形成。与此同时,地鼠卵的胞质也能促使大熊猫精子头发育成雄性原核,异种精卵间的相互作用与同种受精的相似。 细胞松弛素B能阻抑大熊猫雄性原核从地鼠卵皮层迁移到卵的中央,实验表明大熊猫雄性原核的迁移也受异种卵的微丝的控制。 相似文献
2.
Barriers to polyspermy (fertilization of a female gamete by more than one sperm) are essential to successful reproduction
in a wide range of organisms including mammals, echinoderms, fish, molluscs, and algae. In animals and fucoid algae, polyspermy
results in early death of the zygote due to transmission of extra centrioles from the sperm and consequent disruptions to
the mitotic spindle. Accordingly, a variety of mechanisms have evolved to prevent penetration of an egg by more than one sperm,
or more than one sperm nucleus from fusing with an egg nucleus. The evolution of internal fertilization has also provided
an opportunity to limit the number of sperm that gain access to each egg, as occurs in the mammalian female reproductive tract.
Polyspermy and polyspermy barriers in plants have received much less attention. Plants lack centrioles and therefore, polyspermy
would not be expected to cause lethal aberrant spindle organization. However, we find evidence from cytological, genetic and
in vitro fertilization studies for polyspermy barriers in plants. Angiosperms, like mammals, are internally fertilized, and
exert a high level of control over the number of sperm that have access to each female gamete. In particular, regulation of
pollen tube growth ensures that in general only two sperm enter each embryo sac, where one fertilizes the egg and the other
the central cell. Despite this 1:1 ratio of sperm to gametes within the embryo sac, angiosperms still require a mechanism
to ensure that each female gamete is fertilized by one and only one sperm. Here, we present evidence suggesting that a polyspermy
block on the egg may be part of the mechanism that promotes faithful double fertilization. 相似文献
1