BRS embryo Flashcards
All primary oocytes are formed by
month 5 of fetal life
When does formation of primary spermatocytes begin?
Puberty
In the production of female gametes, what cell can remain dormant for 12-40 years
primary oocyte
In the production of male gametes, which cell can remain dormant for 12 years
primordial germ cells
Although a young women enters puberty with 40,000 primary oocytes, she will only ovulate about ___ throughout her reproductive window
480
During meiosis, pairing of homologous chromosomes occurs, permitting large segments of DNA to be exchanged in a process called
crossing over
during ovulation, the secondary oocyte resides at what specific stage of meiosis
metaphase of meiosis II
when do oogonia enter meiosis I and undergo DNA replication to form primary oocytes
during fetal life
where do primordial germ cells initially develop
in the yolk sac at week 4 of embryonic development
woman presents at the emergency department with severe abdominal pain on the right side with signs of internal bleeding. She indicated that she has been sexually active without contraception and missed her last menstrual period. Based on this information, which disorder must be included as an option in the diagnosis?
ectopic tubal pregnancy
when does a secondary oocyte complete its second meiotic division to become a mature ovum
at fertilization
how soon after fertilization occurs within the uterine tube does the blastocyst begin implantation
by day 7
where does the blastocyst normally implant
functional layer of the endometrium
what structure must degenerate for blastocyst implantation to occur
zona pellucida
in oogenesis, what event occurs immediately following the completion of meiosis II
formation of a female pronucleus
what cell type plays the most active role in invading the endometrium during blastocyst implantation
syncytiotrophoblast
the prechordal plate marks the site of the future
mouth
chorion is made up of
extraembryonic somatic mesoderm, cytotrophoblast, syncytiotrophoblast
where does the amniotic cavity develop
within the epiblast
at the end of week 2 of development, what is the composition of the embryonic disc
epiblast and hypoblast
which germ layers are present at the end of week 3 of development
ectoderm, mesoderm and endoderm
what process establishes the three germ layers
gastrulation
the first indication of gastrulation in the embryo is
formation of the primitive streak
somites may differentiate into which of the following? Urogenital ridge Kidneys Notochord Epimeric and hypomeric muscles epithelial lining of the GI that
epimeric and hypomeric muscles
intermediate mesoderm will give rise to
kidneys and gonads
the specialized group of mesenchymal cells that aggregate to form blood islands centrally and primitive blood vessels peripherally are called
cardiac progenitor cells
the epiblast is capable of forming which germ layers
ectoderm, endoderm and mesoderm
what structure is derived from the same embryonic primordial as the dorsal root ganglion
adrenal medulla
what structure is derived from the same embryonic primordial as the kidney
gonads
the anterior and posterior neuropores close during which week of embryonic development
week 4
what condition results from failure of the anterior neuropore to close
anencephaly
A 22 yo pregnant woman at 20 weeks of gestation comes to her ON/GYN for a normal examination. During routine blood tests, her serum alpha-fetoprotein concentration is markedly increased for her gestational age. Ultrasonography reveals spina bifida in the fetus. at what week of gestation did this defect most likely occur?
4-6
Which of the following statements describing the primitive streak is not correct
A. it initially develops in the cephalic portion of the bilaminar disc
B. It identifies the site where formation of embryonic mesoderm is initiated
C. It is the site where the formation of the notochord takes place
D. It determines the body axis of the embryo
E. It is a location where cells of the embryonic ectoderm invaginate
A. is incorrect
Which of the following statements is correct about the cloacal membrane?
A. it is located between the notochord and the primitive streak
B. It is immediately caudal to the primitive knot
C. It is composed of ectoderm, mesoderm, and endoderm
D. It is formed prior to the formation of the primitive streak
D. it is formed prior to the formation of the primitive streak
Which of the following structures is not derived from ectoderm? A. Spinal cord B. Brain C. dermis of skin D. hair follicle s
C. dermis of skin is not an ectodermal derivative
Which of the following structures is not derived from endoderm A. liver B. Skeletal muscle C. smooth muscle D. Cardiac muscle E. kidneys
A. Liver
Which of the following populations of mesodermal masses contributes to the body wall?
A. paraxial mesoderm
B. Intermediate mesoderm
C. Axial mesoderm
D. Somatic layer of lateral plate mesoderm
E. Splanchnic layer of lateral plate mesoderm
D. somatic layer of lateral plate mesoderm contributes to the body wall
Failure to fuse by which of the following structures leads to spina bifida occulta? A. neural folds B. neural arch processes C. vertebral bodies D. neural plate
Neural arch processes
Which of the following statements about meningommyelocele is correct?
A. It leads to immediate death
B. It is usually found in the cervical region of the vertebral column
C. It usually produces no clinical symptoms
D. It involves the vertebral arch, meninges, and nerve tissue
D. It usually involves the vertebral arch, meninges, and nerve tissue
Which of the following statements about neurulation is not correct?
A. NCC migrate from the neuroectoderm before neural tube closure
B. neural plate tissue invaginates to form a nueral groove
C. The notochord induces neural plate formation
D. Neural crest cells induce the formation of the brain
D. neural crest cells induce the formation of brain
Which of the following statements is correct about the development of the neural tube?
A. it develops directly from the cells of the primitive streak
B. it develops from cells of the notochord
C. It develops from ectoderm posterior (dorsal) to the primitive streak
D. It develops from ectoderm posterior (dorsal) to the notochord
D. it develops from ectoderm posterior (dorsal) to the notochord
All of the following are NCC derivatives except A. Neurons in the spinal ganglia B. Neurons in the sympathetic ganglia C. Astrocytes D. Schwann cells
C. astrocytes are not NCC derivatives
The most likely devlopmental process causing anencephaly is A. inadequate neural tube closure B. Excessive prodution of CSF C. excessive skull growth D. Breakage of chromosomes E. Defective osteoblasts
A. inadequate neural tube closures
which of the following statements about the development of the intraembryonic coelem is not correct?
A. it originates by delaminatino of cells from the hypoblast
B. Its formation is linked to partitioning of the lateral plate mesoderm
C. It has broad communication initially with the extraembryonic coelem
D. Its cranial component arises rostral to the oropharyngeal membrane
B. its formation is linked to partitioning of the lateral plate mesoderm
transformation fo the trilaminar embryonic plate into a tubular configuration is accomplished by appearance of which of the following A. primitive streak B. Notochord C. Body folds D. Body stalk
C. body folds
During cephalic folding, which of the following structures does not move ventrally and caudally? A. Septum transversum B. Notochord C. Pericardial cavity D. heart
B. notochord
