Anatomy - Embryology Flashcards
When does menarche occur in females?
Age 12-15
When does puberty occur in males?
13-16
Where does fertilization occur?
Uterine (Fallopian) tube
What is the inferior part of the birth canal?
Vagina
What are the two parts of the uterus?
Upper 2/3 = body
Lower 1/3 = cervix
What is the constricted region between the uterine body & cervix called?
Isthmus
The 2 constricted openings at the superior and inferior uterus are called:
Internal os (body of uterus); external os (opening to vagina)
What are the 3 layers of the uterus? (Superficial to deep)
Perimetrium (thin external)
Myometrium (thick smooth muscle)
Endometrium (thin internal)
What is sloughed off during menstruation?
Functional layer (endometrium)
What structure protects & nourishes the fetus during pregnancy?
Uterus
Who produces estrogen & progesterone?
Ovaries
During spermatogenesis/oogenesis, the first meiotic division …
Chromosome number diploid –> haploid
What are homologous chromosomes?
One from each parent
When do homologous chromosomes pair and cross-over?
Prophase I
What are sister chromatids?
Identical copies of each chromosome
What are homologous chromosomes?
One from mother, corresponding one from father
T/F In meiosis, homologous chromosomes stick together in pairs
True; when paired, non-sister chromatids can trade places (cross-over)
What happens during meiosis II?
Sister chromatids separate
What is it called when homologous chromosomes fail to separate?
Nondisjunction
What is trisomy 21?
Down syndrome (gamete with 24 chromosomes unites with a normal one) * Trisomy 21 = three chromosome 21's
What is Mittelschmerz?
A sign of ovulation; may be used as a sign of ovulation, but more accurate measurements i.e. basal temperature
What are the 4 major hormones that govern ovulation?
Estrogen, progesterone, FSH & LH
What is the acellular hlycoprotein coat that surrounds the secondary oocyte?
Zona pellucia
Degeneration of the corpus luteum is governed by which hormone?
hCG
Contraceptives prevent…
Ovulation
How many sperm per mL semen?
100 million
How much sperm per ejaculation?
3 mL semen / 300 million sperm
What is vasectomy?
Bi-lateral excision of vas deferens
Where is typical site of fertilization?
Ampulla of the uterine tube (proximal to the infundibulum)
What is the corona radiata?
The cellular layer outside the zona pellucida
Differentiate between the trophoblast and the embryoblast?
Embryoblast: discrete group of blastomeres
Trophoblast: thin outer cells that give rise to the embryological placenta
What are the 2 layers of the trophoblast and what special factor do they secrete?
- Cytotrophoblast [cellular layer]
- Syncyntiotrophoblast [pierces endometrium]
* Secrete early pregnancy factor at 24-48 hours post-fertilization
What is the difference between the epiblast and the hypoblast?
Epiblast: will eventually form the embryo
Hypoblast: thin cell lining of the blastocyst cavity [lines primitive yolk sac]
What cells line the primitive yolk sac?
Hypoblast cells
Which chromosome is the male chromosome?
Y
What percentage of pregnancies result in early spontaneous abortion?
45%
What is the commonest reason of spontaneous abortions?
Chromsomal abnormalities
Why might it be important to determine the sex of the cleaving zygote in vitro?
Families with sex-linked diseases
Which part of the blatocyst penetrates the endometrium?
Synciotrophoblast
What does the synciotrophoblast secrete?
hCG (early pregnancy tests)
What is the bilaminar disk?
Epiblast + Hypoblast
What is the chorionic cavity?
The space surrounding the primary yolk sac and amniotic sac, except where the connecting stalk attaches to the cytotrophoblast of the blastocyst
What suspends the embryo, amniontic sac & umbilical vesicle to the chorionic cavity?
The connecting stalk
Where is the commonest site of an ectopic pregnancy?
Uterine tube
Does the morning after-pill (large doses of estrogen) prevent fertilization or implantation?
Implantation – a large amount of estrogen disturbs the normal balance between estrogen and progesterone that is necessary to prepare the endometrium for implantation
Where does fertilization take place?
Uterine tube
Where does implantation take place?
Posterior uterine wall
This type of device can be inserted into the uterus through the vagina & cervix which prevents implantation
IUD (intra-uterine device)
What are “mesenchymal cells”?
Mesoderm – have the potential to differentiate into fibroblasts, chondroblasts and osteoblasts
The notochord is the precursor to: (2)
- Axial skeleton
- Future site of vertebral bodies
* * Nucleus pulposis**
The early embryo has 2 membranes (one caudal, one cranial). What are they?
- Oropharyngeal membrane
2. Cloacal membrane
What structure extends from the caudal wall of the umbilical vesicle into the connecting stalk?
The allantois
The blood vessels of this structure become the umbilical arteries and veins
Allantois
This process forms the neural plate, neural folds and their closure
Neurulation
What are the most common tumors in newborns?
Sacrococcygeal teratoma (remnant of the primitive streak – pluripotent cells – can include tissues derived of all 3 germ layers)
Failure of the neural folds to fuse and form the neural tube can result in: (2 – 1 caudal, 1 cranial)
Caudal: spina bifida cystica
Cranial: anencephaly (meroencephaly)
Differentiate between the products of the 4th left/right pharyngeal arches.
L: aortic arch
R: r. subclavian
Differentiate between the products of the 6th left/right pharyngeal arches.
L: PA, ductus arteriosis
R: PA
Neural crest cells give rise to:
MOTEL PASS
- Melanocytes
- Odontoblasts
- Tracheal cartilage
- Enterochromaffin cells
- Laryngeal cartilage
- Pseudounipolor
- All ganglia/adrenal medulla
- Schwann cells
Differentiate between the derivatives of the ectoderm/mesoderm/endoderm.
Ectoderm: epithelium & communication
Mesoderm: movement (muscles, ligs, cart)
Endoderm: excretory (GI, resp., urinary)
What is the primary imaging modality for the evaluation of the fetus?
Ultrasound
Differentiate between chorionic villus sampling and amniocentesis.
CVS: earlier (sample chorionic tissue)
Amnio: fluid from amniotic cavity
Alpha fetoprotein levels would indicate:
- Open neural tube defects
2. Ventral wall defects (gastroschesis/omphalocele)
How might we measure the age of the fetus?
Chorionic sac size (ultrasound)
What is the general name of functional endometrium of a gravid woman?
Decidua
