ER Practice Q's - Week 2 - Female
Reproductive System and Breast Questions
With Complete Solutions
ANSWER: A: Blastocyst
Rationale: Preimplantation embryos undergo
cleavage division to form an 8- to 16-cell morula
(choice C). Accumulation of fluid within this
compact ball of cells transforms the morula into a
fluid-filled structure referred to as the blastocyst.
As shown in the image, the blastocyst is composed
of two populations of cells: an inner cell mass (ICM)
and an outer epithelium. Gastrula (choice B) refers
to bilaminar embryos composed of epiblast and
hypoblast. Neurula (choice D) refers to post
implantation embryos undergoing neurulation
(folding of the neural tube). Zygote (choice E)
refers to the embryo, shortly after fertilization,
prior to the onset of the first cleavage division.
You are involved in a research project to identify
receptors that mediate implantation of the embryo.
A section of the mouse uterus on day 4.5
postcoitum is stained with periodic acid-Schiff
(PAS) reagent and counterstained with methylene
blue (shown in the image). What is the appropriate
name for the embryo at this stage of early
development?
,(A) Blastocyst
(B) Gastrula
(C) Morula
(D) Neurula
(E) Zygote
ANSWER: E: Trophoblast
Rationale: As the blastocyst develops within the
uterus, outer cells establish tight junctions and
flatten to form a simple squamous epithelium. This
outer layer of cells is referred to astrophoblast
(trophectoderm). Prior to implantation, the
blastocyst escapes (“hatches”) from the zona
pellucida. Once free of the zona pellucida, the 6-
day embryo makes contact with epithelial cells
lining the uterine endometrium to initiate
implantation. Trophoblastic cells actively invade
,the maternal endometrium to establish a substrate
for further development. They form two
populations of cells that contribute to
extraembryonic tissues of the placenta: (1)
proliferative stem cells (cytotrophoblast) and (2)
multinucleatedgiant cells (syncytiotrophoblast).
The human conceptus becomes fully embedded
within the maternal endometrium by day 11.
For the Blastocyst embryo, what is the appropriate
name for the epithelial cells that areadherent to
the apical surface of the uterine endometrium?
(A) Amnioblast
(B) Embryoblast
(C) Inner cell mass
(D) Primitive endoderm
(E) Trophoblast
ANSWER: C: Corpus luteum
Rationale: Implantation of the blastocyst within
the endometrium is only possible during a short
period of time, referred to as the “implantation
window.” This window of uterine receptivity is
regulated by estrogen and progesterone. These
steroid hormones are produced by the corpus
luteum—an endocrine organ that forms in the
ovary after ovulation. The anterior pituitary (choice
B) secretes FSH and LH. None of the other
, endocrine organs secrete estrogen and
progesterone.
Which of the following maternal endocrine tissues/
organs secretes a hormone that controls the
secretory phase of the uterine cycle and helps
establishes a "window" for implantation of the
blastocyst?
(A) Adrenal cortex
(B) Anterior pituitary
(C) Corpus luteum
(D) Graafian follicle
(E) Posterior pituitary
ANSWER: C: Arrest in meiosis I
Rationale: Primordial germ cells (PGCs) leave the
yolk sac during the 4th and 5th weeks of
development and migrate along the dorsal
mesentery of the primitive gut to enter the
developing gonads. Female PGCs undergo
repeated mitotic cell divisions to generate millions
of oogonia. Each oogonium becomes enveloped by
a monolayer of follicular cells that are derived from
the surface epithelium. Within these primordial
follicles, female germ cells enter meiosis and arrest
in prophase of meiosis I. By the7th month of
development, most oogonia have transformed into
primordial oocytes. By contrast, male germ cells
Reproductive System and Breast Questions
With Complete Solutions
ANSWER: A: Blastocyst
Rationale: Preimplantation embryos undergo
cleavage division to form an 8- to 16-cell morula
(choice C). Accumulation of fluid within this
compact ball of cells transforms the morula into a
fluid-filled structure referred to as the blastocyst.
As shown in the image, the blastocyst is composed
of two populations of cells: an inner cell mass (ICM)
and an outer epithelium. Gastrula (choice B) refers
to bilaminar embryos composed of epiblast and
hypoblast. Neurula (choice D) refers to post
implantation embryos undergoing neurulation
(folding of the neural tube). Zygote (choice E)
refers to the embryo, shortly after fertilization,
prior to the onset of the first cleavage division.
You are involved in a research project to identify
receptors that mediate implantation of the embryo.
A section of the mouse uterus on day 4.5
postcoitum is stained with periodic acid-Schiff
(PAS) reagent and counterstained with methylene
blue (shown in the image). What is the appropriate
name for the embryo at this stage of early
development?
,(A) Blastocyst
(B) Gastrula
(C) Morula
(D) Neurula
(E) Zygote
ANSWER: E: Trophoblast
Rationale: As the blastocyst develops within the
uterus, outer cells establish tight junctions and
flatten to form a simple squamous epithelium. This
outer layer of cells is referred to astrophoblast
(trophectoderm). Prior to implantation, the
blastocyst escapes (“hatches”) from the zona
pellucida. Once free of the zona pellucida, the 6-
day embryo makes contact with epithelial cells
lining the uterine endometrium to initiate
implantation. Trophoblastic cells actively invade
,the maternal endometrium to establish a substrate
for further development. They form two
populations of cells that contribute to
extraembryonic tissues of the placenta: (1)
proliferative stem cells (cytotrophoblast) and (2)
multinucleatedgiant cells (syncytiotrophoblast).
The human conceptus becomes fully embedded
within the maternal endometrium by day 11.
For the Blastocyst embryo, what is the appropriate
name for the epithelial cells that areadherent to
the apical surface of the uterine endometrium?
(A) Amnioblast
(B) Embryoblast
(C) Inner cell mass
(D) Primitive endoderm
(E) Trophoblast
ANSWER: C: Corpus luteum
Rationale: Implantation of the blastocyst within
the endometrium is only possible during a short
period of time, referred to as the “implantation
window.” This window of uterine receptivity is
regulated by estrogen and progesterone. These
steroid hormones are produced by the corpus
luteum—an endocrine organ that forms in the
ovary after ovulation. The anterior pituitary (choice
B) secretes FSH and LH. None of the other
, endocrine organs secrete estrogen and
progesterone.
Which of the following maternal endocrine tissues/
organs secretes a hormone that controls the
secretory phase of the uterine cycle and helps
establishes a "window" for implantation of the
blastocyst?
(A) Adrenal cortex
(B) Anterior pituitary
(C) Corpus luteum
(D) Graafian follicle
(E) Posterior pituitary
ANSWER: C: Arrest in meiosis I
Rationale: Primordial germ cells (PGCs) leave the
yolk sac during the 4th and 5th weeks of
development and migrate along the dorsal
mesentery of the primitive gut to enter the
developing gonads. Female PGCs undergo
repeated mitotic cell divisions to generate millions
of oogonia. Each oogonium becomes enveloped by
a monolayer of follicular cells that are derived from
the surface epithelium. Within these primordial
follicles, female germ cells enter meiosis and arrest
in prophase of meiosis I. By the7th month of
development, most oogonia have transformed into
primordial oocytes. By contrast, male germ cells
