Chapter 1/2

Question 1

If ovaries are both removed from woman and she is on replacement hormonal meds- what are affected in her body?

Answer 1

1. Blood levels of FSH and LH
2. Ciliated cells of uterine tube
3. Glandular tissue of the breasts
4. Thickness of endometrium

Question 2

During spermatogenesis, histone is replaced by which of the following, to allow better packing of the condensed chromatin in the head of the spermatozoon?
A. Inhibit 
B. Prostaglandin E
C. Testosterone 
D. Protamine
E. Androgen-binding protein

Answer 2

D. Protamine

Question 3

Which cell type is located outside the blood-testis barrier?
A. Spermatozoon
B. Secondary spermatocyte
C. Spermatid 
D. Primary spermatocyte
E. Spermatogonium

Answer 3

E. Spermatogonium

Question 4

Which of the following cells normally participates in mitotic divisions?
A. Primary oocyte
B. Oogonium
C. Primary spermatocyte
D. Spermatid
E. Secondary spermatocyte

Answer 4

B. Oogonium

Question 5

In a routine chest XRAYS examination, the radiologist sees what appear to be teeth in a mediastinal mass. What is the likely diagnosis, and what is probable embryological explanation for its appearance?

Answer 5

A mediastinal teratoma, which is likely to have arisen
from an aberrant primordial germ cell that became
lodged in the connective tissue near the heart.

Question 6

When does meiosis begin in the female and in the male?

Answer 6

In the female, meiosis begins during embryonic life; in

the male, meiosis begins at puberty.

Question 7

At what stages of oogenesis is meiosis arrested in the female?

Answer 7

At prophase (diplotene stage) of the first meiotic division
and at metaphase of the second meiotic division.

Question 8

What is the underlying cause of most spontaneous abortions during the early weeks of pregnancy?

Answer 8

Chromosomal abnormalities, such as polyploidy or

trisomies of individual chromosomes.

Question 9

What is the difference between spermatogenesis and spermiogenesis?

Answer 9

Spermatogenesis is the entire process of sperm
formation from a spermatogonium. It includes the two
meiotic divisions and the period of spermiogenesis.
Spermiogenesis, or sperm metamorphosis, is the process
of transformation of a postmeiotic spermatid, which
looks like an ordinary cell, to a highly specialized
spermatozoon.

Question 10

The actions of what hormones are responsible for the changes in the endometrium during the menstrual cycle?

Answer 10

Estrogens, secreted by the ovary, support the preovulatory
proliferative phase. From the time of ovulation,
progesterone is secreted in large amounts by the corpus
luteum and is responsible for the secretory phase, which
prepares the endometrium for implantation of an
embryo.

Question 11

Sertoli cells in the testis are stimulated by what two major reproductive hormones?

Answer 11

Follicle-stimulating hormone (FSH) produced by the
anterior lobe of the pituitary gland and testosterone
produced by the Leydig cells of the testis.

Question 12

Airplane example:
A. To whom should the twins be awarded?
B. What should be done with the remaining frozen embryo?

Answer 12

1. Before the plane crash, the issue is who is the “real”
   mother. After the crash, the issue is who gets the
   money—the surrogate mother who claims that she
   is the real mother or the aunt who claims a blood affinity.
   Although these present as legal issues that would likely be
   decided in a court, the concept of what is meant by
   surrogacy also involves psychological and religious issues.
2. This is a very important issue that has not been resolved.
   If the parents had been of a religion that strongly supports
   the rights of embryos to life, should the remaining
   embryos also be implanted into someone, and, if so,
   into whom? In a case where a considerable inheritance is
   involved, the financial implications could cloud the issue.
   If there were no parental money, who would undergo
   the risk and the expense to prevent the frozen embryos
   from being simply thrown out? In many cases of in vitro
   fertilization and embryo transfer, the question of what
   to do with the “extra” frozen embryos when the first
   transfer is successful is a real one. Many frozen embryos
   are being stored at various sites around the world.

Question 13

Of the barriers to sperm survival and transport within the female reproductive tract, low pH is most important in the : 
A. Upper uterine tube
B. Lower uterine tube
C. Uterine cavity
D. Cervix 
E. Vagina

Answer 13

E. Vagina

Question 14

The principal energy source for ejaculated spermatozoa is:
A. Prostatic acid phosphatase
B. Internal glucose
C. Prostatic citric acid
D. Fructose in seminal vesicle fluid
E. Glycogen released from the vaginal epithelium

Answer 14

D. Fructose in seminal vesicle fluid

Question 15

What is the principal hormonal stimulus for ovulation?

Answer 15

The sharp surge of luteinizing hormone produced by the

anterior lobe of the pituitary gland.

Question 16

What is capacitation?

Answer 16

Capacitation is a poorly understood interaction between
a spermatozoon and female reproductive tissues that
increases the ability of the sperm to fertilize an egg. In
some mammals, capacitation is obligatory, but in humans
the importance of capacitation is less well established.

Question 17

Where does fertilization occur?

Answer 17

Fertilization usually occurs in the upper third of the

uterine tube.

Question 18

Name two functions of ZP3 protein of the zona pellucida?

Answer 18

The ZP3 protein acts as a specific sperm receptor through
its O-linked oligosaccharides; much of its polypeptide
backbone must be exposed to stimulate the acrosomal
reaction.

Question 19

What is polyspermy, and how is it prevented after a spermatozoon enters the egg?

Answer 19

Polyspermy is the fertilization of an egg by more than
one spermatozoon. It is prevented through the fast
electrical block on the plasma membrane of the egg and
by the later zona reaction, by which products released
from the cortical granules act to inactivate the sperm
receptors in the zona pellucida.

Question 20

A woman gives birth to septuplets. What is likely reason for the multiple births?

Answer 20

She had probably taken clomiphene for the stimulation

of ovulation. Natural septuplets are almost never seen.

Question 21

When multiple oocytes obtained by laproscopy are fertilized in vitro, why are you up to three embryos implanted into the woman’s uterus, and why are the other embryos commonly frozen?

Answer 21

The introduction of more than one embryo into the tube
of the woman is commonly done because the chance
that any single implanted embryo will survive to the time
of birth is quite small. The reasons for this are poorly
understood. Extra embryos are frozen because if a pregnancy does not result from the first implantation,
the frozen embryos can be implanted without the
inconvenience and expense of obtaining new eggs from
the mother and fertilizing them in vitro.

Question 22

Why do some reproductive technology centers insert spermatozoa under the zona pellucida or even directly into the oocyte?

Answer 22

In cases of incompatibility between the sperm and egg,
poor sperm motility, or deficient sperm receptors in the
zona, introducing the sperm directly into or near the egg
can bypass a weak point in the reproductive sequence of
events.