Introduction to Embryology Flashcards
What is embryology?
Embryology is a branch of anatomy that deals with the formation, early growth and development of living organisms.
……………….. is the area of embryology that deals with changes that cells, tissues, organs and the human body undergo from a sex cell of each parent to the resulting adult
Developmental anatomy
………………. is a branch of embryology and pathology that is concerned with abnormal developments like congenital malformations. It deals with genetic and/or environmental factors that may produce birth defect
Teratology
What is a zygote?
A totipotent diploid cell resulting from the fusion of to haploid gametes; sperm and ovum.
What are totipotent cells?
Immature/stem cell capable of giving rise to any cell type or a complete embryo
Mention the processes through which zygote is transformed into a multi-cellular human being.
cell divisions (cleavage);
cell migration (gastrulation),
programmed cell death (apoptosis),
differentiation, growth and cell rearrangement.
Most developmental changes occur during the ……………
prenatal period: embryonic and fetal periods
What is meant by gestational age?
The age of the embryo or fetus from the first day of the last normal menstrual period (LMP). It is about two weeks longer than the fertilization age because the egg is fertilized about 2 weeks after the first day of menstruation.
What is cleavage?
The series of mitotic cell divisions of the zygote resulting in early embryonic cells called blastomeres. The size of the early embryo remains unchanged because the blastomeres become smaller at each cell division
Infancy refers to ……..
0-12 moths after birth
Childhood courses from ………….
13 moths to puberty
Adolescence courses from ……….
11-19 years
…………… is any cell that results from division of a fertilized egg.
Blastomere
Adulthood is reached by …………
18-21 years
What is meant by a blighted ovum?
An early embryo whose development has ceased
What is fertilization/conception Age?
the age of the embryo or fetus from the time of fertilization(conception)
the embryo with 12 or more blastomeres at 3 to 4 days after fertilization that resembles fruits of mulberry tree is referred to as …………….
A morula
Describe the blastocyst
The embryo with fluid filled cavity with the centrally located cells as the inner cell mass or embryoblast, the primordium of embryo.
What is implantation?
The process by which the blastocyst attaches to the endometrium and embeds in it.
……………………… period of embryonic development is the time between fertilization and the beginning of implantation.
The pre-implantation period
How long is the preimplantation period?
Nearly 6 days
…………… is single layer stage of embryo
Blastula
What is a neurula?
The embryo is referred to as neurula at the stage of neurulation or formation of the neural tube
When does the embryonic stage extend to?
The end of the 8th week of IUL
Define the gastrula?
Gastrula is a three layered or trilaminar embryonic disc. The three germ layers differetiate into the tissues and organs of the embryo.
Conceptus refers to ………………
The embryo and all the structures that develop from it–placenta,amnion,chorion and yolk sac
………………. refers to first recognizable indication for development of an organ or structure.
Primordium
……………. is the developing human after embryonic period
Fetus
The fetal period extends from …………..
9th week to birth
……………….. is a period of three calendar months during a pregnancy
Trimester
What is a trimester?
A period of three calendar months during a pregnancy
………………. is most critical trimester, and why is it?
The first trimester is most critical because embryonic and early fetal development is occurring
What is abortion?
Abortion means the following;
premature stoppage of development
premature expulsion of a conceptus from the uterus
expulsion of an embryo or fetus before it is viable (capable of living outside the uterus
…………………. are birth defects or abnormalities of development present at birth.
Congenital anomalies/malformations
Embryonic development ends at ………….
Day 56 (end of the 8th week)
What the duration of the fetal period?
begins on day 57 (immediately after the embryonic period) and ends when the fetus is completely outside the mother
……………….. can be used to assess the stage of embryonic development
Ultrasonography
……………. is the process whereby one cell divides, giving rise to two daughter cells that are genetically identical to the parent cell
Mitosis
chromatids, are joined at a narrow region common to both called the ……….
Centromere
Chromosomes condense in the prophase, but become distinguishable in ………………..
The prometaphase
the chromosomes line up in the equatorial plane in the …………. stage
Metaphase
……………….. marks the beginning of the anaphase
Division of the centromere of each chromosome
migration of chromatids to opposite poles of the spindle occurs in …………….. phase
Anaphase
Mention the events of the telophase stage
chromosomes uncoil and lengthen,
the nuclear envelope reforms,
and the cytoplasm divides
………… division occurs in somatic cells?
Mitosis
……….. is the cell division that takes place in the germ cell
Meiosis
Define the process “synapsis”
It occurs in meiosis I, homologous chromosomes align them- selves in pairs
…………… separates sister chromatids
Meiosis II
……………. are the interchange of chromatid segments between paired homologous chromosomes
Crossovers
Crossovers, and exchange of genetic material occur beteween paired homologous chromosomes at an area of contact called ………………..
Chiasmata
As separation occurs, points of interchange are temporarily united and form an X-like structure called ………..
Chiasma
What is the essence of meiosis?
Genetic variability is enhanced through crossover, which redistributes genetic material and random distribution of homologous chromosomes to the daughter cells
Each germ cell contains a haploid number of chromosomes, so that at fertilization the diploid number of 46 is restored.
The most common chromosomal abnormalities in abortuses are …………………..
45, X (Turner syndrome), triploidy, and trisomy 16
Normal somatic cells are diploid, or 2n; normal gametes are …………….
haploid, or n.
Euploid refers to ………….
any exact multiple of n e.g. diploid, triploid
………… refers to any chromosome number that is not euploid
Aneuploid
Down syndrome is caused by ………….
Trisomy of chromosome 21
The cells have 47 chromosomes with a sex chromosomal
complement of the XXY type in ……………….. syndrome
Klinfelter
What is a barr body, where is it usually found?
It is formed by condensation of an inactivated X
chromosome;
- Found in males with Klinfelter syndrome
- Present in normal females because one of the X chromosomes is normally inactivated
Klinfelter syndrome is caused by ……………
Non disjunction of the XX homologues.
State the Karyotype of Turner’s syndrome
45, X
……….. is the only monosomy that is compatible with life
Turner’s syndrome
Gonadal dysgenesis and short stature is associated with ……………….
Turner’s syndrome
………………… is a genetic disorder caused by a deletion of the short arm of chromosome 5
Chri-du-chat syndrome
……………….. is a condition characterized by a pattern of abnormal brain development known as lissencephaly
Miller-Dieker syndrome
Chromosomes are ……………….. stained to reveal light and dark banding patterns
Giemsa-stained
