Download Embryology Exam 1 Study Guide Questions for Lecture One 1

Embryology Exam 1 Study Guide
Questions for Lecture One
1. Which of the following migrate from the yolk sac?
a. primary oocytes- As the oogonia enter the first meiotic division late in the fetal period, they are called
primary oocytes. Primary oocytes enter the diplotene stage of prophase I in the early months after birth. They
are held in prophase I of meiosis until ovulation
b. oogonia- During the second through fifth month of pregnancy the primordial germ cells, now properly
called oogonia, undergo intense mitosis in the embryonic ovary. Shortly thereafter, many oogonia undergo
atresia (degeneration). As the oogonia enter the first meiotic division late in the fetal period, they are called
primary oocytes
c. primordial germ cells
d. spermatogonia- For males, primordial germ cells continue to divide by mitosis throughout life or
differentiate into spermatogonia just before puberty. Spermatogonia maintain their population through mitosis
of type A spermatogonia. After puberty, some type A give rise to type B spermatogonia that differentiate into
primary spermatocytes and enter prophase I of meiosis but are not held at the diplotene stage, as are the
oocytes.
2. Most _______ undergo atresia during embryonic development.
a. oogonia
b. spermatogonia- For males, primordial germ cells continue to divide by mitosis throughout life or
differentiate into spermatogonia just before puberty. Spermatogonia maintain their population through mitosis
of type A spermatogonia. After puberty, some type A give rise to type B spermatogonia that differentiate into
primary spermatocytes and enter prophase I of meiosis but are not held at the diplotene stage, as are the
oocytes.
c. spermatocytes- After puberty, some type A give rise to type B spermatogonia that differentiate into
primary spermatocytes and enter prophase I of meiosis but are not held at the diplotene stage
d. graffian follicles- NOT IN THE CHAPTER NOTES
3. About which of the following time periods do oogonia begin the first stage of meiosis?
a. At puberty- For males, primordial germ cells continue to divide by mitosis throughout life or differentiate
into spermatogonia just before puberty. As puberty approaches, continued follicular maturation requires the
action of the pituitary gonadotrophic hormone follicle-stimulating hormone (FSH) on the granulosa cells, which
by this time developed FSH receptors on their surfaces. Shortly before puberty the sex cords acquire lumens,
becoming seminiferous tubules and at puberty primordial germ cells are transformed into type A spermatogonia
[2n, 2c].
b. Late in the fetal period.
c. At the time of ovulation- In the primary oocyte, the first three stages of prophase occur promptly, but
shortly after birth the process is held in the diplotene stage until ovulation. At puberty and just before ovulation
(egg breaks free from ovary), the process continues through diakenesis, metaphase I, anaphase I, and telophase
I. tertiary (Graafian) follicle protrudes at the surface of the ovary (stigma) and sharp spike in LH from the
pituitary leads to completion of meiosis I and ovulation. After ovulation, the Graafian follicle becomes a corpus
luteum. Unless fertilization occurs 24 hours after ovulation, the egg will die.
d. After fertilization- At fertilization, for each of the 23 chromosomes (1n, 1c) donated from the egg there is
a homologous (related and hopefully normal) chromosome donated from a sperm, and vice versa. When
fertilization does occur, a zygote is formed by the union of egg and sperm pronuclei and two more polar bodies
for a total of three. Unless fertilization occurs 24 hours after ovulation, the egg will die.
4. The stage at which chiasma are formed in the tetrads, for either primary oocytes or primary
spermatocytes, is which of the following?
a. diplotene stage of prophase I
b. metaphase of meiosis I- Next, the chromosomes consisting of two chromatids joined together at a
centromere, line up on an equatorial plane. This is metaphase where the microtubules form a mitotic spindle
associated with the centromeres and centrioles. There is no nuclear membrane here.
c. diplotene stage of meiosis II
c. prophase of meiosis II
5. Which of the following has the chromosomal characteristic 2n, 4c?
a. primordial germ cell- [2n, 2c]During the third week, primordial germ cells, which arise in the
extraembryonic mesoderm near the base of the allantois, become recognizable in the lining of the yolk sac.
Soon these cells migrate into the wall of the gut and the dorsal mesentery as they make their way to the gonads,
where they differentiate into oogonia or spermatogonia. During the second through fifth month of pregnancy
the primordial germ cells, now properly called oogonia, undergo intense mitosis in the embryonic ovary. For
males, primordial germ cells continue to divide by mitosis throughout life or differentiate into spermatogonia
just before puberty. When primordial germ cells have arrived at the indifferent gonad they differentiate into
oogonia and acquire flat epithelial cells from the surface of the gonad, follicular cells, that later will become
granulosa cells. At puberty primordial germ cells are transformed into type A spermatogonia [2n, 2c].
b. primary oocyte
c. spermatid- [1n, 1c] Secondary spermatocytes complete meiosis II, becoming spermatids [1n, 1c], which
shed excess cytoplasm, the residual body, and differentiate into spermatozoa. Spermatogenesis is divided into
two parts. (1) spermatocytogenesis – spermatogonia up to spermatids, and (2) spermiogenesis – spermatids to
mature sperm.
d. secondary spermatocyte- [1n, 2c] Primary spermatocytes give rise to secondary spermatocytes that will
go through meiosis II to make spermatids, and finally, spermatozoa. Primary spermatocytes pass through the
blood-testes barrier (made by Sertoli cells) and complete meiosis I to become secondary spermatocytes [1n, 2c].
6. Granulosa cells of a follicle originate from which of the following?
a. Mesoderm of the gonad- The endoderm of the yolk sac is lined on the outside by well-vascularized
extraembryonic mesoderm. During the third week, primordial germ cells, which arise in the extraembryonic
mesoderm near the base of the allantois, become recognizable in the lining of the yolk sac.
b. Surface epithelial cells of the ovary.
c. Yolk sac endoderm- The endoderm of the yolk sac is lined on the outside by well-vascularized
extraembryonic mesoderm. During the third week, primordial germ cells, which arise in the extraembryonic
mesoderm near the base of the allantois, become recognizable in the lining of the yolk sac.
d. Stroma of the ovary- While this is occurring, the stroma of the ovary tissue directly around the granulosa
cells differentiates into theca folliculi.
7. Granulosa cells and _________ cells have receptors for follicle stimulating hormone.
a. theca interna- The theca interna has receptors for luteinizing hormone (LH). The theca interna cells
produce androgens (testosterone). This is not a derivative of surface epithelium cells
b. Leydig- Testosterone is made by Leydig cells. These respond to LH
c. theca externa- The theca externa is somewhat inert and there is no hormone production.
d. Sertoli
8. As granulosa cells proliferate and an antrum is formed, the primary oocyte sits on a mound of
those and this mound is called the __________.
a. theca externa- The theca externa is somewhat inert and there is no hormone production.
b. corona radiata- The layer granulosa cells still adherent to the zona pellucida is called the corona radiata.
c. cumulus oophorus
d. stigma- The tertiary (Graafian) follicle protrudes at the surface of the ovary (stigma) and sharp spike in
LH from the pituitary leads to completion of meiosis I and ovulation.
9. Which of the following is not a part of a spermatozoon?
a. residual body
b. head- . The sperm cell has a head with the acrosome and nucleus,
c. midpiece- The sperm cell has a midpiece with the centrioles and proximal flagellum with the
mitochondria
d. flagellum- Located on the midpiece
10. Blood-testes barriers are formed by _________.
a. Leydig cells making androgen-binding protein
b. Leydig cells with LH receptors
c. Sertoli cells making androgen-binding protein
d. Sertoli cells making testosterone
Questions for Lecture Two
1. Which of the following hormones is secreted by the pituitary gland?
a. gonadotropin-releasing hormone- When puberty begins in the female, gonadotropin-releasing
hormones (GnRH) made in the hypothalamus act on the pituitary gland.
b. FSH
c. progesterone- The surge of LH from the pituitary transforms the Graafian follicle into a corpus
luteum (yellow body) when ovulation occurs. This begins the progestational (secretory) phase (days 14
– 28). Here there is a dominance of progesterone that is secreted by the corpus luteum.
d. androgens- The theca interna cells produce androgens, which pass to the granulosa cells.
2. Normally, the menstrual cycle is about _____ days.
a. 10
b. 19
c. 28
d. 36
3. Both the oocyte and granulosa cells form the ___________.
a. zona pellucida
b. cumulus oophorus- The egg, now a secondary oocyte, is located in a small mound of cells, the cumulus
oophorus.
c. theca interna- The theca folliculi differentiates into a vascular theca interna. The cells of the theca interna
possess receptors for LH, secreted by the pituitary. The theca interna cells produce androgens, which pass to
the granulosa cells.
d. yolk sac- Primordial germ cells originate from the yolk sac.
4. The secondary follicle is so termed when which of the following is formed.
a. cumulus oophorus- The egg, now a secondary oocyte, is located in a small mound of cells, the cumulus
oophorus.
b. zona pellucida- As the primary follicle takes shape, a prominent, translucent membrane called the zona
pellucida forms between the primary oocyte and its enveloping granulosa cells. Both oocyte and granulosa cells
contribute to the zona pellucida. The zona pellucida contains sperm receptors. Blastocyst hatches from here
just before implantation into the endometrium.
c. polar body- Essentially the left over, nonfertile eggs left over from meiosis II.
d. antrum
5. Which of the following has receptors for LH and also produces testosterone?
a. theca externa- The theca folliculi differentiates into an outer fibrous capsule, the theca externa.
b. granulosa cells- As the primary follicle takes shape, a prominent, translucent membrane called the zona
pellucida forms between the primary oocyte and its enveloping granulosa cells. Both oocyte and granulosa cells
contribute to the zona pellucida.
c. theca interna
d. zona pellucida- As the primary follicle takes shape, a prominent, translucent membrane called the zona
pellucida forms between the primary oocyte and its enveloping granulosa cells. Both oocyte and granulosa cells
contribute to the zona pellucida. The zona pellucida contains sperm receptors. Blastocyst hatches from here
just before implantation into the endometrium.
6. The secretory phase of the menstrual cycle is due to the hormonal influence of __________
on the endometrium.
a. estrogens- FSH stimulates granulosa cells to produce estrogens. The influence of FSH induces the
granulosa cells to synthesize the enzyme (aromatase) that converts the theca-derived androgens into estrogens.
b. FSH- FSH stimulates granulosa cells to produce estrogens. The influence of FSH induces the granulosa
cells to synthesize the enzyme (aromatase) that converts the theca-derived androgens into estrogens.
c. testosteroned. progesterone
7. For the corpus luteum of pregnancy, the __________ will produce the hormone for the
correct answer in question #6.
a. granulosa lutein cells
b. corona radiata- With ovulation, the secondary oocyte (ovum) has with it, the (1) zona pellucida, (2)
corona radiata, and (3) a polar body. The sperm needs to pass through the corona radiata before penetrating
the zona pellucida. The corona radiata is lost within two days of the start of cleavage.
c. theca externa- The theca folliculi differentiates into an outer fibrous capsule, the theca externa.
d. trophoblast- The outer cell mass next to the zona pellucida is called the trophoblast. The outer cell mass
forms the trophoblast (cytotrophoblast) which helps form the placenta.
8. Completion of meiosis I in the oocyte occurs ______________.
a. after the egg is fertilized- completion of meiosis II just before ovulation
b. several hours before ovulation
c. in the late fetal period
d. in the yolk sac- hypoblast forms the yolk sac
9. Fertilization usually occurs in __________ of the fallopian tube.
a. fimbria- The secondary oocyte [1n, 2c] is swept up into the fimbria of the fallopian tube.
b. infundibulumc. ampulla
d. isthmus10. If the egg is fertilized, the corpus luteum is maintained for a few months by placental
secretion of _______.
a. FSH- FSH stimulates granulosa cells to produce estrogens. The influence of FSH induces the granulosa
cells to synthesize the enzyme (aromatase) that converts the theca-derived androgens into estrogens.
b. estrogen- FSH stimulates granulosa cells to produce estrogens. The influence of FSH induces the
granulosa cells to synthesize the enzyme (aromatase) that converts the theca-derived androgens into estrogens
c. HCG
d. LH- Excreted by the pituitary gland. Just before and during a menstrual period, this set of primary follicles
begins to mature and secrete 17β-estradiol in response to FSH and LH from the pituitary.
11. Before sperm can fertilize an egg it must undergo __________ in the female reproductive
tract.
a. capacitation
b. spermiogenesis- The process of the creation of sperm.
c. an acrosomal reaction- An acrosomal reaction where there is fusion of the outer acrosomal membrane
with the zona pellucida and acrosomal proteins are released.
d. meiosis II- With fertilization, resumption and completion of meiosis II in the secondary oocyte [1n, 2c] is
accomplished with a resultant definitive oocyte [1n, 1c] and its female pronucleus.
12. For the egg, meiosis II is complete when which of the following has occurred?
a. ovulation
b. fertilization
c. acrosomal reaction- An acrosomal reaction where there is fusion of the outer acrosomal membrane with
the zona pellucida and acrosomal proteins are released.
d. zona reaction- A zona reaction occurs when cortical granules diffuse into the zona pellucida and
hydrolyze the ZP3 receptor molecules, making it impossible for other sperm to penetrate the zona pellucida.
13. When a cavity has formed in the blastomeres that form the ball of cells of the early embryo,
the embryo is then considered to be a _________.
a. morula- About 3 days after fertilization and 3 divisions later, a 16-cell morula (mulberry) is formed.
b. zygote- Mitotic spindles are formed, thus making a zygote
c. gamete- Sex Cells
d. blastocyst
14. For the early embryo, cells that form the trophoblast come from the _________.
a. zona pellucid- As the primary follicle takes shape, a prominent, translucent membrane called the zona
pellucida forms between the primary oocyte and its enveloping granulosa cells. Both oocyte and granulosa cells
contribute to the zona pellucida. The zona pellucida contains sperm receptors. Blastocyst hatches from here
just before implantation into the endometrium.
b. inner cell mass- The cells of the embryo become compacted (compaction) with a mass of inner cells
surrounded by a population of outer cells.
c. outer cell mass
d. theca externa- The theca folliculi differentiates into an outer fibrous capsule, the theca externa.
15. Mittelschmerz is _________________.
a. periods beginning in the middle of the week
b. pain upon ovulation
c. a German car
d. how you say "Wednesday" in German
Questions for Lecture Three
1. The outer cell mass differentiates into the ____________.
a. trophoblast
b. morula- About 3 days after fertilization and 3 divisions later, a 16-cell morula (mulberry) is formed.
c. epiblast- The inner cell mass differentiates into an upper layer known as the epiblast
d. embryoblast
2. Amnioblasts are derived from the ____________.
a. hypoblast- The inner cell mass differentiates into a lower layer called the hypoblast (primitive
endoderm, extraembryonic endoderm).
b. cytotrophoblast- At the abembryonic pole, flat cells form a thin membrane that lines the inside
of the cytotrophoblast. Cells appear between the primary yolk sac [parietal endoderm, Heuser's
(exocoelomic) membrane] and the cytotrophoblast, forming connective tissue called extraembryonic
mesoderm. Mesoderm lining the inside of the cytotrophoblast and outside of the amnion is
extraembryonic somatopleuric mesoderm.
c. syncytiotrophoblast- Cells of the cytotrophoblast penetrate the syncytiotrophoblast. Human
chorionic gonadotropin (HCG) is produce by the syncytiotrophoblast. They are multinuclear cells) and
are derived from fused cytotrophoblast cells.
d. epiblast
3. The cavity of the primitive yolk sac is also called the ___________.
a. chorionic cavity- The chorionic cavity encloses the primitive (primary) yolk sac and amniotic
cavity. The connecting stalk (future umbilical cord) crosses the chorionic cavity, connecting the embryo
to the placental area. Exocoelomic cysts are formed in the chorionic cavity.
b. amniotic cavity- A small cavity appears in the epiblast and becomes the amniotic cavity.
c. exocoelomic cavity
d. lacunae- The trophoblast shows more vacuoles in its syncytial component. The vacuoles enlarge
to become lacunae.
4. Extraembryonic mesoderm that adheres to the outside of the yolk sac is ______________.
a. somatopleuric mesoderm- Mesoderm lining the inside of the cytotrophoblast and outside of the
amnion is extraembryonic somatopleuric mesoderm.
b. cytotrophoblastic- At the abembryonic pole, flat cells form a thin membrane that lines the inside
of the cytotrophoblast. Cells appear between the primary yolk sac [parietal endoderm, Heuser's
(exocoelomic) membrane] and the cytotrophoblast, forming connective tissue called extraembryonic
mesoderm. Mesoderm lining the inside of the cytotrophoblast and outside of the amnion is
extraembryonic somatopleuric mesoderm.
c. splanchnopleuric mesoderm
d. the chorionic plate- The extraembryonic mesoderm lining the inside of the cytotrophoblast is
known as the chorionic plate.
5. Primary villi are projections of __________ that just start to penetrate the ___________.
a. endometrium / syncytiotrophoblast
b. cytotrophoblast / syncytiotrophoblast
c. syncytiotrophoblast / endometrium
d. extraembryonic mesoderm / umbilical cord
6. When _____________, it is probably an ectopic pregnancy.
a. there are very high levels of hCG
b. spotting about the 13th day of pregnancy
c. pain during ovulation
d. there is severe abdominal pain at about 6 or 7 weeks gestation
Questions for Lecture Four
1. Gastrulation begins with formation of ___________.
a. Henson's node- At the anterior end of the primitive streak is a small, but well-defined accumulation of
cells, called the primitive node or Henson's node. The node is an elevated area of cells that surrounds a
primitive pit. The node is of developmental significance because it is the area through which migrating cells are
channeled into a rod-like mass of mesenchymal cells called the notochord and a group of cells anterior to that,
the prechordal plate.
b. the notochord- Migrating cells are channeled into a rod-like mass of mesenchymal cells called the
notochord. Cranial to the notochord is a small region where embryonic ectoderm and endoderm abut without
any intervening mesoderm. This is the oropharyngeal (buccopharyngeal) membrane: the future oral cavity. A
prechordal plate forms between the tip of the notochord and the buccopharyngeal membrane. Cells of the
notochord separate from the endodermal roof of the yolk sac and form the definitive notochord.
c. primitive streak
d. placenta- The placenta consists of two components: (1) a fetal portion, derived from the chorion
frondosum or villous chorion, and (2) a maternal portion, derived from the decidua basalis (functional layer of
endometrium shed at parturition).
2. From which of the following are all of the embryonic germ layers derived?
a. epiblast
b. hypoblast- Associated with the yolk sac. After the primitive streak is well established, the majority of cells
spread out between the epiblast and hypoblast to form embryonic (intraembryonic) mesoderm. By the time the
mesoderm has formed a discrete layer in the embryo, the upper layer (remains of the former epiblast) is called
the ectoderm, and the lower germ layer, which has displaced the original hypoblast, is called the endoderm.
c. amnion cellsd. trophoblast- By the beginning of third week, the trophoblast is characterized by primary villi that consist
of a cytotrophoblastic core covered by a layer of syncytial cells.
3. The notochord and prechordal plate develop from cells that passed through the________.
a. primitive streak- Gastrulation begins with the primitive streak, which is not clearly seen till the 15 or 16day embryo. The primitive streak is a midline condensation of cells derived from the epiblast. With the
appearance of the primitive streak, the anteroposterior (craniocaudal) and left-right axes can be readily
identified. As cells of the epiblast reach the primitive streak, they change shape and pass through it on their way
to forming a new cell layer beneath (ventral to) the epiblast. The movement of the cells through the primitive
streak results in the formation of a primitive groove.
b. allantois- When the cloacal membrane appears, the posterior wall of the yolk sac forms a small
diverticulum, the allantois.
c. primitive node
d. buccopharyngeal membrane- A prechordal plate forms between the tip of the notochord and the
buccopharyngeal membrane.
4. Which of the following structures have ectoderm and endoderm directly apposed to each
other?
a. prechordal plate- A prechordal plate forms between the tip of the notochord and the buccopharyngeal
membrane. This is a small aggregation of mesodermal cells closely apposed to the endoderm and was some of
the first cells to pass through the primitive node. The prechordal plate is instrumental in formation of the
forebrain.
b. notochord- Migrating cells are channeled into a rod-like mass of mesenchymal cells called the notochord.
Cranial to the notochord is a small region where embryonic ectoderm and endoderm abut without any
intervening mesoderm. This is the oropharyngeal (buccopharyngeal) membrane: the future oral cavity. A
prechordal plate forms between the tip of the notochord and the buccopharyngeal membrane. Cells of the
notochord separate from the endodermal roof of the yolk sac and form the definitive notochord.
c. yolk sac- Shortly, the cells of the notochordal plate temporarily spread out and fuse with the embryonic
endoderm (from streak cells that replaced the hypoblast), resulting in the formation of a transitory neurenteric
canal that connects the emerging amniotic cavity with the yolk sac.
d. cloacal membrane
5. The neurenteric canal connects the amniotic cavity with the _________.
a. chorionic cavity- The chorionic cavity encloses the primitive (primary) yolk sac and amniotic cavity. The
connecting stalk (future umbilical cord) crosses the chorionic cavity, connecting the embryo to the placental
area. Exocoelomic cysts are formed in the chorionic cavity.
b. lacunae- The trophoblast shows more vacuoles in its syncytial component. The vacuoles enlarge to
become lacunae.
c. yolk sac
d. exocoelomic cyst- Exocoelomic cysts are formed in the chorionic cavity.
6. The _____________ is instrumental in development of the forebrain.
a. prechordal plate
b. notochord- Migrating cells are channeled into a rod-like mass of mesenchymal cells called the notochord.
Cranial to the notochord is a small region where embryonic ectoderm and endoderm abut without any
intervening mesoderm. This is the oropharyngeal (buccopharyngeal) membrane: the future oral cavity. A
prechordal plate forms between the tip of the notochord and the buccopharyngeal membrane. Cells of the
notochord separate from the endodermal roof of the yolk sac and form the definitive notochord.
c. buccopharyngeal membrane- A prechordal plate forms between the tip of the notochord and the
buccopharyngeal membrane.
d. allantois- When the cloacal membrane appears, the posterior wall of the yolk sac forms a small
diverticulum, the allantois.
7. Situs inversus, reversed left-right asymmetry, is due to abnormalities in _________.
a. blood flow
b. lefty-1
c. dynein
d. fate map
8. When __________ cells begin to penetrate primary villi, secondary villi are formed.
a. cytotrophoblastic- By the beginning of third week, the trophoblast is characterized by primary villi that
consist of a cytotrophoblastic core covered by a layer of syncytial cells. Cytotrophoblastic cells penetrate the
syncytium until they reach the maternal endometrium. The inner cytotrophoblastic shell is the original
cytotrophoblast with extraembryonic mesoderm lining its inside. Anchoring or stem villi extend from the "inner"
cytotrophoblastic shell (chorionic plate) to the outer cytotrophoblastic shell abutting the endometrium.
b. syncytiotrophoblastic c. endometriald. mesodermal
9. Villi that extend from the inner (original) cytotrophoblast to the outer cytotrophoblast
are called, __________ villi.
a. primary villi- By the beginning of third week, the trophoblast is characterized by primary villi that consist
of a cytotrophoblastic core covered by a layer of syncytial cells. Later, mesodermal cells penetrate the core of
the primary villi and grow toward the deciduas.
b. anchoring villi
c. tertiary villi- By the end of the third week, mesodermal cells in the core of the villus begin to differentiate
into blood cells and small blood vessels. The villus is now a tertiary villus or definitive villus. Capillaries in
tertiary villi make contact with capillaries in the connecting stalk and chorionic plate, both formed by
extraembryonic (somatopleuric) mesoderm.
d. free villi10. If there is too little mesoderm formed in the caudal part of the embryo, ___________
will be the result.
a. holoprosencephaly- Holoprosencephaly includes a broad spectrum of defects, all based on defective
formation of the forebrain (prosencephalon) and structures whose normal formation depends on influences of
the forebrain. Defects can include altered facial structures with, mental retardation, heart defects, and postnatal
growth. Fetal alcohol syndrome, from ingesting as little as 3 ounces of alcohol per day during the first 4 weeks
of pregnancy, can result in holoprosencephaly.
b. sirenomelia
c. sacrococcygeal teratoma- If remnants of the primitive streak persist in the coccygeal region, pleuripotent
cells may proliferate and form these tumors. These contain a bizarre mixture of fat, cartilage, muscle, hair, and
glandular tissue
d. immotile cilia- Kartagener's syndrome, the situs inversus is associated with respiratory symptoms due to
abnormalities of the dynein arms in cilia (immotile cilia).
11. A teratoma will form if the ___________does not disappear.
a. primitive node- At the anterior end of the primitive streak is a small, but well-defined accumulation of
cells, called the primitive node or Henson's node. The node is an elevated area of cells that surrounds a
primitive pit. The node is of developmental significance because it is the area through which migrating cells are
channeled into a rod-like mass of mesenchymal cells called the notochord and a group of cells anterior to that,
the prechordal plate.
b. prechordal plate- A prechordal plate forms between the tip of the notochord and the buccopharyngeal
membrane. This is a small aggregation of mesodermal cells closely apposed to the endoderm and was some of
the first cells to pass through the primitive node. The prechordal plate is instrumental in formation of the
forebrain.
c. buccopharyngeal membrane- A prechordal plate forms between the tip of the notochord and the
buccopharyngeal membrane.
d. primitive streak
Questions for Lecture 5
1.
The neural plate develops from the ____________.
a. the hypoblast- helps for the yolk sac
b. epiblast
c. cytotrophoblast- derives syncytiotrophoblast
d. yolk sac
2.
Elevation of the lateral edges of the neural plate will immediately form ____________.
a. the neural tube- anterior & cranial neuropores are at the end of the neural tube.
b. the posterior neuropore
c. neural crest cells- sympathetic ganglia & Schwann cells develop from neural crest cells
d. neural folds
3.
Which of the following is not a derivative of ectoderm?
a. anterior neuropore
b. neural tube- anterior and cranial neuropores are at the ends
c. gut tube - derived from endoderm
d. neural crest cells – odotoblasts, melanocytes, ganglia cells are derived specifically from
4.
Neural crest cells may give rise to many tissue types. Which of the following is not one
of them
a. enamel of teeth
b. dorsal root (sensory) ganglia
c. melanocytes
d. autonomic postganglionic nerve cells
5.
DiGeorge's syndrome and ___________ are the result of defective neural crest cell
migration.
a. persistent truncus arteriosus
b. sacrococcygeal teratoma – persistant primitive streak will result in the formation
c. sirenomelia
d. situs inversus
6.
Lateral plate mesoderm associated with the yolk sac is called, _____________.
a. somatic mesoderm – dorsal layer
b. extraembryonic mesoderm
c. visceral mesoderm - blend w/ mesoderm covering the yolk sac
d. amniotic mesoderm
7.
Somites are formed at the expense of __________ which are segmentations of
the _____________ mesoderm.
a. neuromeres / paraxial
b. neuromeres / lateral plate
c. somitomeres / lateral plate
d. somitomeres / paraxial
8.
A somite will undergo further development with its ventromedial part partitioning off
into a ___________.
a. dermomyotome – dorsal 1/2
b. sclerotome - vertebrae are formed from
c. myotome – medial lip
d. dermatome - lateral part of the dermomyotome
9.
In the yolk sac, angioblasts are derived from ______________.
a. splanchnic mesoderm
b. endoderm
c. somatic mesoderm
d. ectoderm
10. The midgut communicates with the yolk sac through the ___________.
a. allantois – evagination of the hind gut
b. vitelline duct
c. oropharyngeal membrane – has only ectoderm and endoderm
d. cloacal plate – proctodeal membrane
11. Parenchyma of the digestive-associated glands, gut lining, and respiratory system
epithelium are derived from __________.
a. the notochord
b. mesoderm
c. endoderm
d. ectoderm
12. The time of gestation from 3 to 8 weeks is called __________ or period of organogenesis.
a. the embryonic period
b. the fetal period
c. bilaminar period
d. trilaminar period