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Flashcards in Exam 1 Review Deck (47):

During spermatogenesis, histone is replaced by which of the following, to allow better packing of the condensed chromatin in the head of the spermatazoan?

A. Inhibin
B. Prostaglandin E
C. Testosterone
D. Protamine
E. Androgen-binding protein

D. Protamine


Which cell type is located outside the blood-testis barrier?

A. Spermatozoon
B, Secondary spermatocyte
C. Spermatid
D, Primary spermatocyte
E. Spermatogonium

E. Spermatogonium


Which of the following cells normally participates in mitotic divisions?

A. Primary oocyte
B. Oogonium
C. Primary spermatocyte
D. Spermatid
E. Secondary spermatocyte

B. Oogonium


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

Abherrant primordial germ cells


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

Female: embryonic life
Male: puberty


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

First: diplotene stage of prophase in meiosis I
Second: Metaphase II


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

Chromosomal abnormalities (aneuploidy or euploidy)


What is the difference between spermatogenesis and spermiogenesis?

Spermatogenesis: process of sperm formation from spermatogonium
Spermiogenesis: transformation of postmeiotic spermatid


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

Estrogen, progesterone


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

FSH, testosterone


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

E. Vagina


The principal energy source for ejaculated spermatazoa is:

A. Prostatic and phosphatase
B. Internal glucose
C. Prostatic citric acid
D. Fructose in seminal vesicle fluid
E. Glycogen released from the vaginal epithelium

D. Fructose in seminal vesicle fluid


What is the principal hormonal stimulus for ovulation?

Sharp LH surge


What is capacitation?

Required for sperm to have the ability to fertilize an egg


Where does fertilization occur?



Name 2 functions of the ZP3 protein of the zona pellucida

Stimulates acrosomal reaction; causes massive influx of Ca2+ and Na+/efflux of H+


What is polyspermy and how is it prevented after sperm interacts with the egg?

Polyspermy: fertilization of egg by more than 1 sperm
Prevention by fast and slow block


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

Clomiphene was probably taken to stimulate pregnancy as septuplets are rarely naturally seen


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

This increases the chance of embryo survival; embryos are frozen to prevent inconvenience and cost to mother if the first round of IVF is not successful


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

Bypasses weak points in reproductive events


What is the most common condition associated with spontaneously aborted embryos?

A. Maternal imprinting
B. Paternal imprinting
C. Ectopic pregnancy
D. Chromosomal abnormalities
E. Lack of X-chromosomal inactivation

D. Chromosomal abnormalities


What tissue from implanting embryo directly interfaces with the endometrial connective tissue?

A. Corona radiata
C. Extraembryonic mesoderm
D. Epiblast
E. Syncytiotrophoblast

E. Syncytiotrophoblast


Identical twinning is made possible by what process or property of the early embryo?

A. Regulation
B. Aneuploidy
C. Paternal imprinting
D. Maternal imprinting
E. X-chromosomal inactivation

A. Regulation


The zona pellucida:

A. Aids in penetration of the endometrial epithelium
B. Serves as a source of nutrients for the embryo
C. Prevents premature implantation of the cleaving embryo
D. All of the above
E. None of the above

C. Prevents premature implantation of the cleaving embryo


What is the importance of the ICM of the cleaving embryo?

The embryonic body proper arises from ICM


Parental imprinting is a phenomenon showing that certain homologous maternal and paternal chromosomes have different influences on the development of the embryo. Excess paternal influences result in the abnormal development of what type of tissue at the expense of the embryo itself?

Trophoblastic tissue


What is the function of integrins in implantation?

Allow trophoblast of the embryo to adhere to the uterine epithelium


What is the cellular origin of the syncytiotrophoblast of the implanting embryo?

Cells from cytotrophoblast


A woman who is 2-3 months pregnant suddenly develops severe lower abdominal pain. In the differential diagnosis, the physician must include the possibility of what condition?

Rupture of uterine tube containing implanted embryo


What is a homeobox?

Highly conserved sequence of 180 amino acids encoding 60 amino acid homeodomain; products are transcription factors


Which of the following is a transcription factor?

B. Pax
D, Notch
E. Wnt

B. Pax


Where in the cell is the retinoic acid receptor located?



A mutation of what receptor is the basis for basal carcinomas of the skin?

A. Patched
B. Retinoic acid
C. Notch
D. FGF receptor
E. None of the above

A. Patched


Zinc finger or helix-loop-helix arrangements are characteristic of members of what class of molecules?

A. Proto-oncogenes
B. Signaling molecules
C. Receptors
D. Transcription factors
E. None of the above

D. Transcription factors


Based on your knowledge of paralogous groups, which gene would be expressed most anteriorly in the embryo?

A. Hoxa-13
B. Hoxc-9
C. Hoxd-13
D. Hoxb-1
E. Hoxb-6

D. Hoxb-1


Sonic hedgehog is produced in which signaling center?

A. Notochord
B. Intestinal portals
C. Floor plate of neural tube
D. Zone of polarizing activity
E. All of the above

E. All of the above


The principal inductor in primary neural induction is the:

A. Hypoblast
B. Primitive streak
C. Extraembryonic mesoderm
D. Notochordal process
E. Embryonic ectoderm

D. Notochordal process


Which of the following tissues arises from cells passing through the primitive streak?

A. Embryonic endoderm
B. Hypoblast
C. Cytotrophoblast
D. Primary yolk sac
E. Amnion

A. embryonic endoderm


Cells of which germ layer are not present in the oropharyngeal membrane?

A. Ectoderm
B. Mesoderm
C. Endoderm
D. All are present

B. Mesoderm


The prechordal plate plays an important role in regionalization of the:

A. Notochord
B. Forebrain
C. Embryonic mesoderm
D. Primitive node
E. Hindbrain

B. Forebrain


Brachyury, a deficiency in caudal tissues in the body, is caused by a mutation in what gene?

A. Lim-1
B. Noggin
C. T
D. Shh
E. Activin

C. T


Which layer of the bilaminar embryo gives rise to all embryonic tissue proper?



Of what importance is the primitive node in embryonic development

Acts as organizer; induces nervous system and embryonic axis


The migration of mesodermal cells from the primitive streak is facilitated by the presence of what molecule of the extracellular matrix?

Hyaluronic acid and fibronectin


What molecule can bring about mesodermal induction of an early embryo?

Vg1 and activin


At what stage in the life history of many cells are cell adhesion molecules lost?

Migratory phase


A 35 year old married male with a history of chronic respiratory infections is found on routine x-ray examination to have dextrocardia. Further studies reveal complete situs inversus. He has been going to a different clinic for a completely different problem, which is related to the same underlying defects. What is the most likely clinic?

A. Urology
B. Dermatology
C. Infertility
D. Orthopedic
E. Oncology

C. Infertility: because of respiratory problems associated with situs inversus, this man probably has a mutation of the dynein gene. Commonly, such individuals also have immotile sperm, a condition that would lead to infertility