80 Questions
What is the correct sequence of events during the first week of development?
Fertilization, Cleavage of the zygote, Blastocyst formation, Implantation
When does the fetal period begin during human development?
At week nine
What is the correct term for the study of development from fertilized egg through the eighth week?
Embryology
How is prenatal development divided in terms of time?
By trimesters
Where does fertilization normally occur in humans?
Uterine tube
What process occurs within 12-24 hours after ovulation?
Fertilization
What is the function of zona pellucida in relation to implantation?
Prevents implantation at an abnormal site
When does the blastocyst usually orient with its inner cell mass towards the endometrium?
6 days after fertilization
What happens about 7 days after fertilization in relation to the blastocyst?
The blastocyst attaches more firmly to the endometrium
Which phase is the endometrium in when the blastocyst attaches to the uterine wall?
Secretory phase
What is the functional layer of the endometrium known as after implantation?
Decidua
What happens to the endometrial glands around the time of blastocyst attachment?
They enlarge
What is the primary function of capacitation in the fertilization process?
To enable the sperm to fertilize the ovum
What is the primary role of the acrosome reaction?
To enable the sperm to break through the zona pellucida
What is the primary mechanism that prevents polyspermy?
The depolarization of the membrane
What is the primary function of the zona pellucida after fertilization?
To become impermeable to other sperms
What is the primary function of the uterine milk?
To provide nourishment for the developing morula
What is the primary function of the blastocyst cavity?
To reorganize the blastomeres around a fluid-filled cavity
What is the primary function of the embryoblast?
To develop into the embryo
What is the primary function of the trophoblast?
To develop into the outer chorionic sac and the fetal portion of the placenta
What is the primary purpose of the shedding of the zona pellucida?
To permit implantation into the endometrial lining of the uterus
What is the primary event that restores the diploid number of chromosomes?
The fusion of the male and female pronuclei
Where does the blastocyst usually orient during implantation?
Towards the myometrium
What process occurs about 7 days after fertilization in relation to the blastocyst?
Attachment to the endometrium more firmly
What happens to the endometrial glands around the time of blastocyst attachment?
They enlarge
When does the blastocyst attach to the uterine wall following implantation?
2 days after becoming surrounded by endometrium
What is the functional layer of the endometrium known as following implantation?
Decidua
What is the primary role of the zona pellucida after fertilization?
Prevents implantation at an abnormal site
What happens to the endometrium at the time of blastocyst attachment?
It forms new blood vessels
What is the correct term for a region in the decidua based on its position relative to the site of the implanted blastocyst?
Decidual basalis
What does the blastocyst secrete before burrowing into the endometrium?
Enzymes
What is happening at this time when the endometrium is in its secretory phase?
It is preparing for implantation
Implantation occurs about 6 days after fertilization.
True
The blastocyst attaches to the uterine wall before secreting enzymes and burrowing into the endometrium.
False
The decidua is the name given to the functional layer of the endometrium after implantation.
True
The endometrium becomes more vascularized before the blastocyst attaches more firmly to it.
True
The zona pellucida plays a role in preventing implantation at an abnormal site.
True
The inner cell mass of the blastocyst always orients towards the posterior portion of the uterus during implantation.
False
The blastocyst remains free within the uterine cavity for about 3 days before attaching to the uterine wall.
False
Following implantation, different regions of the decidua are named based on their positions relative to the site of the implanted blastocyst.
True
Endometrial glands enlarge before becoming more vascularized around the time of blastocyst attachment.
True
The endometrium is in its secretory phase when the blastocyst attaches more firmly to it.
True
The blastocyst attaches to the uterine wall before secreting enzymes and burrowing into the endometrium.
False
Implantation occurs about 6 days after fertilization.
True
The zona pellucida plays a role in preventing implantation at an abnormal site.
True
The inner cell mass of the blastocyst always orients towards the posterior portion of the uterus during implantation.
False
The decidua is the name given to the functional layer of the endometrium after implantation.
True
Endometrial glands enlarge before becoming more vascularized around the time of blastocyst attachment.
False
The blastocyst remains free within the uterine cavity for about 3 days before attaching to the uterine wall.
False
Endometrial glands enlarge before secreting enzymes around the time of blastocyst attachment.
True
What is the significance of the zona pellucida in relation to implantation?
Prevents implantation at an abnormal site
Describe the orientation of the blastocyst during implantation.
Inner cell mass toward the endometrium
What is the functional layer of the endometrium known as following implantation?
Decidua
When does the blastocyst attach to the uterine wall following implantation?
About 2 days after free floating in the uterine cavity
How are different regions of the decidua named after implantation?
Based on their positions relative to the site of the implanted blastocyst
What is the process where the genetic material from a haploid sperm and a haploid secondary oocyte merges into a single diploid nucleus?
Fertilization
Where does fertilization normally occur in humans?
Uterine tube
How does the sperm reach the uterine tube for fertilization?
Swim with the help of flagella (tail)
When does fertilization usually occur in relation to ovulation?
Within 12-24 hours after ovulation
What is the term for the study of development from the fertilized egg through the eighth week?
Embryology
What is the significance of the acrosome reaction in fertilization?
The acrosome reaction allows the sperm to break through the Zona pellucida by releasing proteolytic enzymes like acrosin and trypsin.
Describe the process of cleavage in the development of a zygote.
Cleavage involves rapid mitotic cell divisions of the zygote, resulting in the formation of blastomeres and eventually a solid sphere of cells called the morula.
What is the role of the trophoblast in the development of the blastocyst?
The trophoblast forms the outer superficial layer of the blastocyst and eventually develops into the outer chorionic sac and fetal portion of the placenta.
Explain the importance of the blastocyst cavity in embryonic development.
The blastocyst cavity is a fluid-filled space within the blastocyst that helps reorganize cells and differentiate into the embryoblast and trophoblast.
What triggers the hatching of the blastocyst from the zona pellucida?
The blastocyst secretes an enzyme that digests a hole in the zona pellucida, allowing it to squeeze out and prepare for implantation.
Match the following terms with their correct descriptions:
Embryo = Developing human from fertilization through the eighth week Fetus = Developing human from week nine until birth Prenatal development = Time from fertilization to birth, including embryonic and fetal periods Trimesters = Periods of three calendar months each during prenatal development
Match the following events with their occurrences during the first week of development:
Fertilization = Merging genetic material into a diploid nucleus Cleavage of zygote = First week event characterized by cell division Blastocyst formation = Formation of a hollow ball of cells Implantation = Attachment of blastocyst to the uterine wall
Match the following processes with their descriptions in fertilization:
Fertilization = Merging genetic material from sperm and secondary oocyte Sperm migration = Swimming to uterine tube with help of flagella and prostaglandins Uterine contractions = Facilitating migration of sperm from vagina into uterine cavity Changes in sperm = Undergoing modifications prior to fertilization
Match the following terms with their correct definitions:
Embryonic period = Development from fertilization through the eighth week Fetal period = Development from week nine until birth Embryology = Study of development from the fertilized egg through the eighth week Prenatal development = Time from fertilization to birth, including embryonic and fetal periods
Match the following events with their timings during prenatal development:
Embryonic period = Extends from fertilization through the eighth week Fetal period = Begins at week nine and continues until birth Trimesters = Divided into periods of three calendar months each First week of development = Characterized by significant events like fertilization and cleavage
Match the following events during implantation with the correct timing:
Blastocyst loosely attaches to endometrium = 6 days after fertilization Blastocyst attaches more firmly to endometrium = 7 days after fertilization Endometrium becomes more vascularized = Around the time of blastocyst attachment Blastocyst secretes enzymes and burrows into endometrium = After attaching to uterine wall
Match the following descriptions with the correct terms:
Functional layer of the endometrium after implantation = Decidua Regions of decidua based on position relative to blastocyst = Different regions Primary purpose of the shedding of zona pellucida = Preventing implantation at abnormal site Role in preventing implantation at abnormal site = Zona pellucida
Match the following statements with the correct events during implantation:
Endometrial glands enlarge = Before becoming more vascularized Blastocyst orientation during implantation = Inner cell mass towards endometrium Endometrium in its secretory phase = After the blastocyst attaches to uterine wall Blastocyst remains free within uterine cavity before attachment = Approximately 2 days
Match the following factors with their primary functions:
Blastocyst cavity = Primary function is not specified Embryoblast = Primary function is not specified Trophoblast = Development of the blastocyst Uterine milk = Primary function is not specified
Match the following terms with their descriptions:
Hatching of blastocyst from zona pellucida trigger = Not specified in text Fetal period beginning time point = Not specified in text Prenatal development time division basis = Not specified in text Orientation of blastocyst during implantation = Inner cell mass towards endometrium
Match the following events in fertilization and embryonic development:
Acrosome reaction = Allows sperm to break through Zona pellucida Capacitation = Biochemical process enabling sperm to fertilize ovum Fusion of male and female pronuclei = Restores diploid number of chromosomes Formation of blastocyst cavity = Reorganizes cells around a fluid-filled cavity
Match the following stages in early embryonic development with their descriptions:
Morula stage = Solid sphere of cells surrounded by zona pellucida Blastocyst stage = Formation of embryoblast and trophoblast cell populations Cleavage stage = Rapid mitotic cell divisions of the zygote Implantation stage = Attachment into the endometrial lining of the uterus
Match the following terms with their functions in fertilization and implantation:
Zona pellucida shedding = Permits hatching of blastocyst from it Uterine milk secretion = Provides nourishment for developing morula Endometrial glands enlargement = Before becoming more vascularized around blastocyst attachment Trophoblast formation = Develops into outer chorionic sac and fetal portion of placenta
Match the following timeframes with their corresponding events in embryonic development:
First cleavage completion = About 6 hours after zygote formation 32-cell stage = Entry of fluid forming blastocyst cavity Hatching of blastocyst = Around 5 days after fertilization Implantation in uterus = After zona pellucida shedding and hatching
Match the following structures with their roles in fertilization and early embryonic development:
Acrosome = Contains enzymes for breaking through Zona pellucida Embryoblast = Develops into the embryo internally Blastocoel = Large fluid-filled cavity reorganizing blastomeres Female pronucleus = Forms after completion of meiosis II in oocyte
Learn about the stages of human development from fertilization through the eighth week (embryonic period) and from week nine until birth (fetal period). Explore the terms embryo and fetus, and understand the different periods of prenatal development.
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