دانلود کتاب The Sperm Cell - Production, Maturation, Fertilization, Regeneration

Eggs are made for sperm. Sperm are made for eggs.
All other (body) cells are made to support, directly or
indirectly, the development of eggs and sperm and the
survival of their united product: the zygote – the next
generation. he prime function of spermatozoa is to
deliver the male genome safely into eggs. Any errors
during sperm formation, maturation and union with
eggs will result in serious problems in themale’s fertility
and in the wellbeing of the ofspring.
his book covers our current knowledge of (1) the
formation of spermatozoa, (2) the preparation of spermatozoa
for fertilization, (3) the union of spermatozoa
with eggs, (4) the awakening of ‘sleeping’ eggs by spermatozoa
leading to embryo development, (5) genomic
and nongenomic (e.g. environmental) factors afecting
the development and fertility of spermatozoa, and
(6) the challenges of overcoming male (sperm) fertility
problems. Information compiled in each chapter
should be considered a stepping stone to better
understanding and better control of male fertility and
infertility.

The very first chapter of this book mentions the
possible production of ‘artificial human spermatozoa’
from pluripotent stem cells such as human iPSCs.
Obviously, it is not appropriate to use live animals or
get assistance from live animal cells to achieve this
goal. To eliminate or minimize the stress and risks
these cells would face during their transformation into
haploid cells, we must learnmuchmore about what is
really happening in the natural environment of spermatogenic
cells, within the testes.he last chapter considers
the value of the mouse as a model for the study
of mammalian fertility and infertility. Is the mouse a
perfect animal model to use for the study of fertility
and infertility of all mammals, including humans?
Although the mouse is certainly one of the most heavily
used model animals for studying mammalian fertility
and reproduction, we must remember that each
animal uses species-speciic tactics to produce its ofspring.
What is found in one species must be extrapolated
to other species with caution.

Today, it is theoretically possible to reproduce any
mammals without males. In fact, hundreds of cows
have already been produced by somatic cell nuclear
transfer. Clearly, males are not essential for animal
and human reproduction. Why are there males?
At the beginning of life on Earth, there were no
males. Females reproduced by themselves. During the
course of evolution, a bisexual mode of reproduction
emerged, and it has been maintained in most animals,
including humans. Compared with animals propagating
unisexually (females only), animals using a bisexual
mode of reproduction seemto be less vulnerable to
extinction in the face of constantly changing, competitive
environments. Technically, human cloning (nonsexual
reproduction) is possible today. In other words,
humans can reproduce without males. Is this what we
desire? A few years ater the birth of Dolly (a cloned
sheep) andmany clonedmice, I gave talks to groups of
people about animal and human cloning. At the end of
my talk I asked the audience if they wanted to live in
a world without men. With no exception, women did
not want to live in the worldwithoutmen. ‘It would be
boring. We cannot use men?hat would be horrible.’
Men are needed by women, and we will stay that way.
When I started research as an undergraduate student,
I thought everything written in books and
research papers was a fact. I now know that what is
written is authors’ interpretations or just a part of
the whole story. Many things written in books and
reported in original papers will be modiied and even
discarded during the next 40–50 years. Science progresses
that way.

The comprehensive collection of topics that compose
this new edition of he Sperm Cell provide readers
with a map and compass to chart a course for
future investigations. It is the readers’ task ater reading
these highly topical research areas to determine what
subjects are let unclear and compelling, what next
courses might be important to follow and what burgeoning
questions are yet to be studied.

Ryuzo Yanagimachi, PhD
Professor Emeritus, Department of Anatomy,
Biochemistry and Physiology, Institute of Biogenesis
Research, John A. Burns School of Medicine, University
of Hawaii, Honolulu, Hawaii