876
UNIT SIX
Sperm for the future. Some servicemen left frozen samples of sperm at
sperm banks before reporting for active duty, along with written statements
expressing their wishes for their wives to use the sperm to conceive children
should they not return.
POSTMORTEM SPERM RETRIEVAL
medical examiner collected a sperm sample and sent it to California Cryobank
(a sperm bank), where it lay deeply frozen for more than a year. In the summer
of 1978, Dr. Cappy Rothman, medical director of the bank, used the defrosted
sperm to fertilize one of Gaby’s eggs. On March 17, their daughter was born. It
was the F
rst case of “postmortem sperm retrieval” and use in which the father
had not actively participated in the decision. In other cases, the dying men had
had time to state, in writing, their wishes to be fathers posthumously.
Postmortem sperm retrieval raises legal and ethical issues. In another case,
a woman conceived twins sixteen months after her husband had died of leu-
kemia at age thirty, with his consent. But the Social Security Administration
refused to provide survivor beneF
ts to their daughters, claiming that the man
was not a father, but a sperm donor. The Massachusetts Superior Court reversed
this decision.
Postmortem sperm retrieval, like other assisted reproductive technologies, is
not regulated at the federal level in the United States, so bioethicists suggest that
men document their wishes, and have identiF
ed situations to avoid:
Someone other than a spouse wishing to use the sperm
A too-hasty decision based on grief
Use of the sperm for monetary gain
Some nations, including Germany, Australia, Canada, and Sweden, ban the
procedure.
B
ruce and Gaby Vernoff, in their early thirties, had delayed
becoming parents, confident that their good health would
make pregnancy possible. But Bruce suddenly died of an
allergic reaction to a medication. Gaby knew how much he
had wanted to be a father, so she requested that physicians
take some of Bruce’s sperm after his death. Thirty hours after Bruce died, the
23.1
INTRODUCTION
A sperm cell and a secondary oocyte unite, forming a zygote,
and the journey of prenatal development begins. Following
thirty-eight weeks of cell division, growth, and specializa-
tion into distinctive tissues and organs, a new human being
enters the world.
Humans grow, develop, and age.
Growth
is an increase
in size. In humans and other many-celled organisms, growth
entails an increase in cell numbers as a result of mitosis,
followed by enlargement of the newly formed cells and of
the body.
Development,
which includes growth, is the continuous
process by which an individual changes from one life phase
to another. These life phases include a
prenatal period
(pre-
na
tal pe
re-od), which begins with the fertilization of an egg
cell and ends at birth, and a
postnatal period
(po
¯st-na
tal
pe
re-od), which begins at birth and ends with death.
PRACTICE
1
Distinguish between growth and development.
2
Distinguish between prenatal and postnatal.
23.2
PREGNANCY
The union of a secondary oocyte and a sperm cell is called
fertilization
(fer
tı˘-lı˘-za
shun), or conception, which typi-
cally takes place in a uterine tube.
Pregnancy
(preg
nan-se)
is the presence of a developing offspring in the uterus.
Pregnancy consists of three periods called trimesters, each
about three months long.
Transport of Sex Cells
Ordinarily, before fertilization can occur, a secondary oocyte
must be ovulated and enter a uterine tube. During sexual
intercourse, the male deposits semen containing sperm cells
in the vagina near the cervix. To reach the secondary oocyte,
the sperm cells must then move upward through the uterus
and uterine tube. Prostaglandins in the semen stimulate lash-
ing of sperm tails and muscular contractions within the walls
of the uterus and uterine tube aid the sperm cells’ journey.
Also, under the infl
uence of high concentrations of estrogens
during the ± rst part of the reproductive cycle, the uterus and
cervix contain a thin, watery secretion that promotes sperm
transport and survival. Conversely, during the latter part of
the cycle, when the progesterone concentration is high, the
female reproductive tract secretes a viscous fl
uid that ham-
pers sperm transport and survival
(f
g. 23.1)
.
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