Abstract
Mammalian oocytes microsurgically injected with spermatozoa can develop into
normal offspring. Apparently the oocyte has the ability to decompose or
eliminate such sperm components as the plasma membrane and acrosomal contents,
which normally do not enter its cytoplasm. Species in which normal offspring
were obtained by direct sperm injection include: human, mouse, rabbit, horse,
sheep, cattle, pig, and monkey. In the mouse, normal offspring can also be
obtained routinely by the injection of round spermatid nuclei into oocytes.
This suggests that all post-meiotic modifications of spermatozoa
(spermiogenesis, sperm maturation, capacitation and the acrosome reaction)
evolved as processes solely dedicated to delivering male genomes into female
gametes. Birth of normal off-spring after injection of spermatocytes into
maturing or mature oocytes suggests that the mechanisms controlling meiosis of
male and female germ cells are similar, if not the same. Spermatozoa do not
need to be morphologically normal or alive in the conventional sense to
participate in embryo development; as long as they have intact genomes, they
are able to produce normal offspring. Chromosomes within the first and second
polar bodies can be used as substitutes for female pronuclei for the
production of normal offspring. The nuclei of adult somatic cells can be used
for production of animals. This procedure, involving introduction of cell
nuclei into enucleated oocytes (genomic cloning), is rather inefficient at
present. Many obstacles must be overcome before it is accepted as a safe,
novel method to reproduce scientifically, medically or economically valuable
animals. For human cloning the prime consideration must be the welfare of the
child.
Subject
Developmental Biology,Endocrinology,Genetics,Molecular Biology,Animal Science and Zoology,Reproductive Medicine,Biotechnology
Cited by
24 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献