histology

A baby born to an alcoholic mother had microcephaly and cardiac abnormalities and died despite resuscitative efforts. During which of the following periods of pregnancy is alcohol most teratogenic?

3rd to 9th weeks

The heart of an embryo first begins beating at which of the following ages?

4 weeks

The blood vessels of the umbilical cord are derived from:

Allantois

Which of the following processes during fertilization is CORRECT regarding prevention of polyspermy?

Alteration of the oocyte plasma membrane and zona pellucida due to the release of enzymes from the cortical granules

Which of the following structures is derived from ectoderm?

Anterior pituitary (adenohypophysis)

Which of the following structures is NOT derived from the foregut?

Appendix

Which of the following statements concerning development of the zygote is CORRECT?

At around 5-6 days, the blastocyst loses its zona pellucida and implants on the endometrium as a result of the trophoblast layer

Which of the following statements regarding mesodermal cell migration is NOT CORRECT?

Cells migrate in all regions between the epiblast and hypoblast

Which of the following characteristics is similar for spermatogenesis and oogenesis?

DNA replication during meiosis

The greater omentum is derived from which of the following embryonic structures?

Dorsal mesogastrium

The epidermis of skin is derived from:

Ectoderm

Which of the following structures form the wall of the gut?

Endoderm and splanchnic mesoderm

Which of the following is the MOST IMPORTANT component for maintenance of blood-brain barrier integrity?

Endothelial tight junctions

During the formation of the trilaminar embryo, ectoderm and mesoderm are derived from:

Epiblast

During the 3rd week of development, the notochordal cells are derived from:

Epiblast cells that migrate to the primitive node (knot)

A newborn child has an abnormally formed mandible, ears, and palate. He is diagnosed with mandibulofacial dysostosis. This syndrome is due to abnormal development of which of the following structures?

First pharyngeal arch

A 17-year-old male is examined by a physician, who notes a mass at the back of the young man's tongue. The physician biopsies the mass, and the pathology report comes back with a diagnosis of normal thyroid tissue. The occasional presence of such tissue at the back of the tongue is related to the embryonic origin of the thyroid near which of the following structures?

Foramen cecum

Which of the following processes is involved in the formation of the three germ layers?

Gastrulation

Which of the processes establishes the three definitive germ layers?

Gastrulation

Which one of the following statements is INCORRECT?

Go is a checkpoint found in the S-phase of the cell cycle.

High doses of alcohol in the 2nd and 3rd week of embryonic development may result in:

Holoprosencephaly

Which hormone is first produced by the syncytiotrophoblast cells of the early placenta to maintain the viability of the corpus luteum?

Human chorionic gonadotropin

Damage to the basal plate region of the neural tube would MOST LIKELY affect development of the:

Hypoglossal nucleus (XII)

Which one of the following substances crosses the placental barrier?

IgG

From which of the following fetal vessels do the umbilical arteries arise?

Iliac arteries

Which of the following placental components is derived from the mother rather than the fetus?

Lacunar network

Which of the following respiratory system components is derived from neural crest?

Laryngeal cartilage

A patient, who appears to be female, is found to be 46,XY. The patient's vagina is very shallow, ending in a blind pouch, and there are palpable masses in the labia. The diagnosis of testicular feminization syndrome is made. Which of the following was most likely present during the early fetal life of this individual?

MIF (Mullerian inhibitory factor)

Physical examination of a young boy reveals discharge of urine from the umbilicus. The physician concludes that the urachus has failed to fuse. Which of the following structures is the normal adult remnant of the fused urachus?

Median umbilical ligament

Which of the following embryonic structures gives rise to the adrenal cortex?

Mesoderm

During development, the formation of the kidney is induced by which of the following structures?

Metanephric duct

At the time of ovulation, the developing egg is arrested at which stage of development?

Metaphase stage of meiosis II

A 25-year-old female presents to her obstetrician after taking a home pregnancy test with a positive result. She states that twins run in her family and would like an ultrasound to determine if she has a twin pregnancy. Radiographic studies confirm that the embryo has split at the blastocyst stage. Splitting of the embryo at the blastocyst stage results in which of the following?

Monozygotic twins

Calcitonin producing cells are derived from:

Neural crest cells

A neonate is found to have a sacrococcygeal teratoma that contains several different tissue types resulting from a persistence of the primitive streak. The primitive streak normally gives rise to which of the following structures?

Notochord

A mutation affecting the development of the diencephalon could interfere with the secretion of which of the following hormones?

Oxytocin

Which of the following is a receptor for vibratory pressure?

Pacinian Corpuscle

The junction of the epithelium derived from the ectoderm of the proctodeum and the endoderm of the hindgut is roughly indicated by the line:

Pectinate line

The intraembryonic coelomic cavity located cranial to the oropharyngeal (buccopharyngeal) membrane becomes what structure?

Pericardial cavity

A newborn presents to you with incomplete development of neural crest cells. Which of the following might be infected?

Pia mater

Most of the oocytes in the ovary of a prepubescent girl are in which meiotic stage?

Prophase of the first meiotic division

A neuroscientist discovers a way to selectively label neural crest cells in a developing laboratory animal. After birth, he sacrifices the animal and examines the tissue to search for labeled cells. Which of the following cell types will contain the label?

Pseudounipolar cells

DNA is duplicated in the cell cycle during the:

S phase.

Which of the following statements regarding the DNA content of cells is CORRECT?

Secondary spermatocytes have 2n DNA

Most drugs taken during early pregnancy are transported across the placental barrier primarily by:

Simple diffusion

With respect to teratrogenic insult the most critical period of development of the palate is from the end of the week until the beginning of the week:

Sixth, ninth

Which of the following cell types is present two years after birth?

Spermatogonia

As a TA in histology, you are asked, "Where in the epidermis is there the most mitotic activity?" You answer:

Stratum basalis

All of the following features are characteristic of apoptosis except one.

Swelling of the cell.

Which of the following cell types is involved in the production of placental estrogen?

Syncytiotrophoblast

The placental Barrier at 7 months of fetal development is composed of:

Syncytiotrophoblast and endothelium of fetal capillaries

Which of the following features regarding the second week of development is CORRECT?

Syncytiotrophoblast cells are involved in eroding maternal sinusoids to establish the primitive uteroplacental circulation

Which of the following structures gives rise to the umbilical arteries and vein?

The allantois

Which of the following structures is derived from the ectodermal germ layer?

The central nervous system

Which of the following statements concerning the fertilization process is CORRECT?

The cortical granules release enzymes that alter the oocyte plasma membrane and the zone pellucida thus preventing polyspermy

During the second week of embryonic development:

The embryo proper is referred to as a bilaminar germ disc

Which of the following statements concerning gametogenesis is CORRECT?

The follicular cells of primordial follicles secrete oocyte maturation inhibitor (OMI) that stops the development of the primary oocyte

Which of the following statements is CORRECT concerning the third week of development?

The notochord induces the overlying ectoderm to form the neural plate

Which one of the following statements is INCORRECT?

The nucleosomal structure can be made even more compact by phosphorylation of the nuclear lamins.

Which of the following statements is CORRECT during the 2nd week of embryonic development?

The prechordal plate develops from the hypoblast

Which of the following statements is CORRECT during the 2nd week of development?

The prochordal plate which forms at around day 14 of development is derived from the hypoblast layer

Which of the following statements concerning embryonic development is CORRECT?

The trophoblast cells differentiates into syncytiotrophoblast and cytotrophoblast

During the first six days of embryonic development:

The zona pellucida disappears around the 5-6 day stage of development

Which of the following statements concerning fertilization is NOT CORRECT?

The zonal reaction allows other sperms to penetrate the oocyte

Which statement is CORRECT regarding melanocytes?

They are derived from neural crest cells

A 7-year-old patient presents with a mass in the anterior midline of the neck, slightly above the larynx. The mass is mobile and elevates upon protrusion of the tongue. This mass is most likely a cyst that developed from which of the following embryonic structures?

Thyroglossal duct

Which of the following substances DOES NOT cross the placental barrier?

Triglycerides

A PSA level is drawn from a 54-year-old man as part of a routine health evaluation. Which of the following embryonic structures gives rise to the organ being screened for carcinoma?

Urogenital sinus

Which of the following structures is involved in the formation of primordial germ cells?

Yolk sac

During embryological development, hematopoiesis occurs in different organs at different times. Which of the following are the correct organs, in the correct sequence, at which hematopoiesis occurs embryologically?

Yolk sac, liver, spleen and lymphatic organs, bone marrow

During neurulation, the neuroectodermal cells that delaminate to form neural crest cells give rise to

autonomic ganglia

The lining of the intervillous spaces are

composed of syncytiotrophoblast cells

Blood cell formation occurs in the embryo proper around:

day 13, day 21

The notochord forms on approximately what day after conception?

day 17

The prochordal plate is a group of tall columnar cells that

determine the future site of the mouth cavity

As a result of the cranio-caudal and lateral foldings of the embryo, the hindgut that is formed is lined by

endoderm

During the second week of development, the embryo proper is composed of

epiblast and hypoblast

A newborn boy does not pass meconium until 48 hours after his birth. Several weeks later his mother complains that he has not been passing stool regularly. Anorectal manometry reveals increased internal anal sphincter pressure on rectal distention with a balloon. The patient's disorder may be attributed to

failure of neural crest cells to migrate into the colonic wall

During the process of fertilization

in the oocyte, the tail of the sperm remains functional after zygote formation

Cells having basal infoldings are characteristic of

ion transport

Mesoderm is found in all regions of the embryo EXCEPT

oropharyngeal membrane

The notochordal rod (process) increases in length as a result of migration of cells from the

primitive node

Which of the pharyngeal pouches develops into the palatine tonsil?

second

The intraembryonic mesoderm divides the lateral plate mesoderm into

somatic and splanchnic mesoderm

During the final stages of fetal development (5 months to term) the placental barrier is composed of

syncytiotrophoblast and endothelial of fetal capillaries

The primitive uteroplacental circulation occurs as a result of

syncytiotrophoblast cells eroding the lining of maternal blood vessels and allowing the blood to enter the lacunae (spaces)

During the 2nd week of development, the

syncytiotrophoblast erodes the lining of the maternal blood vessels to establish the primitive uteroplacental circulation

During early embryonic development

the blastocyst has develop an inner cell mass and a trophoblast layer by day 5-6

During the 2nd week of development

the germ disc is made up of an epiblast and hypoblast layer of cells

During the 2nd week of development

the primitive uteroplacental circulation is established as a result of the activity of syncytiotrophoblast cells on maternal sinusoids

Myoblasts from the occipital myotomes are believed to give rise to the muscles of the:

tongue

In the third week of embryonic development primitive blood cells begin to form first in the

yolk sac