Embryology Flashcards
Which of the three germ layers will give rise to connective tissue?
mesoderm
Name the cell mass that form the floor of the amniotic cavity.
epiblast
The neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, and pineal are derived from which primitive layer?
neuroectoderm
The ANS, chromaffin cells of adrenal medulla, parafollicular cells, and laryngeal cartilage are derived from which primitive layer?
neural crest
Which of the three germ layers will give rise to the epithelial lining of the respiratory tract?
endoderm
Trace the seven steps of spermiogenesis, from spermatogonia to spermatozoa.
spermatogonia (46xy), primary spermatocyte, first meiotic division, 2 secondary spermatocytes (one 23x, one 23y), second meiotic division, 4 spermatids (two 23x, two 23y), 4 spermatozoa (two 23x, two 23y)
Which structure contains a fluid-filled cavity that separates the blastomere into two distinct parts?
blastula
Which of the three germ layers will give rise to the nervous system?
ectoderm
Name the precursor of the ectoderm.
epiblast
Which structure contains 12-15 blastomeres?
morula
What is the postnatal derivative of the notochord?
nucleus pulposus of the intervertebral disk
Which germ layers arise from the primitive streak?
intra-embryonic mesoderm and endoderm
Where does fetal erythropoiesis occur in the 3rd to 8th weeks?
yolk sac
How many spermatids are produced from one spermatogonia?
4
What is the genetic complement of a spermatogonia cell?
46 XY
Which monosaccharide is the main energy supply for sperm?
fructose
Which structure induces the ectoderm to form neuroectoderm (neural plate)?
notochord
Muscles, bone, CV structures, lymphatics, blood, spleen, and adrenal cortex are derived from which primitive layer?
mesoderm
The bilaminar disk is formed within which week?
week 2
What is the function of ductus arteriosus in fetal circulation?
deoxygenated blood from SVC is expelled into the pulmonary artery and ductus arteriosus to the lower body of the fetus.
What is the spermatic complement of a spermatocyte that has undergone the first meiotic division?
one 23x and one 23y (secondary spermatocytes)
Branchial pouches are derived from which primitive layer?
endoderm
Which structures does the truncus arteriosus gives rise to?
ascending aorta and pulmonary trunk
What does the embryonic ductus venosus become after birth?
ligamentum venosum
Branchial clefts are derived from which primitive layer?
ectoderm
What is the function of foramen ovale in fetal circulation?
most oxygenated blood reaching the heart via the IVC is diverted through the foramen ovale and pumped out of the aorta to the head.
What kind of blood (oxygenated/deoxygenated) do the umbilical arteries carry?
deoxygenated blood from fetus to the placenta
The gut tube epithelium and derivatives (lungs, liver, pancreas, thymus, thyroid, parathyroid) are derived from which primitive layer?
endoderm
Days 15-28 make up which phase of the menstrual cycle?
luteal (secretory) phase
Which structure closes at birth after the infant takes its first breath?
ductus arteriosus
What kind of blood (oxygenated/deoxygenated) is carried by the umbilical vein?
oxygenated blood from placenta to the fetus
Name the two main components of the placenta in the second week.
cytotrophoblast and syncytiotrophoblast
Name the stages of embryogenesis from day zero to implantation at the end of week one.
fertilization (day 0), zygote (day 2), morula (day 3), blastocyst (day 5), implantation (day 6)
Days 1-4 in the menstrual cycle make up which phase?
menstrual phase
Monozygotic twins share ___ amniotic sacs, ___ placentas, and ___ chorions.
2, 1, 1
Which of the three germ layers will give rise to blood vessels?
mesoderm
Which of the three germ layers will give rise to the CV system?
mesoderm
How many cavities in the second week of fetal development and what are they?
amniotic cavity and yolk sac
Dizygotic (fraternal) twins share ___ amniotic sacs, ___ placentas, and ___ chorions
2, 2, 2
Name the process whereby immature spermatids become spermatozoa.
spermiogenesis
The adenohypophysis, lens of eye, epithelial linings, and epidermis are derived from which primitive germ layer?
surface ectoderm
When do primary oocytes begin and complete meiosis I?
being during fetal life, complete just prior to ovulation
Which of the three germ layers will give rise to glands that open into the GI tract?
endoderm
Branchial arches are derived from which primitive layer?
mesoderm and neural crests
What does the embryonic foramen ovale become after birth?
fossa ovalis
How many germ layers are present in the third week and what are they?
ectoderm, mesoderm, endoderm
Trace the five steps of oogenesis from primary oocyte to mature oocyte.
primary oocyte in primary follicle, first meiotic division, secondary oocyte (23x) in mature follicle and first polar body, second meiotic division, mature oocyte (23x) and second polar body (23x)
Which structure does the right common cardinal vein and right anterior cardinal vein gives rise to?
superior vena cava
Name the cell mass that forms the roof of the exocoelemic cavity.
hypoblast
Which of the three germ layers will give rise to glandular cells of the liver and pancreas?
endoderm
Which of the three germ layers will give rise to the lining of the GI tract?
endoderm
Days 4-14 make up which phase of the menstrual cycle?
follicular (proliferative) phase
Where does fetal erythropoiesis occur during the 9th to 28th weeks?
spleen
Which of the three germ layers will give rise to blood cells?
mesoderm
Name the process that converts a bilaminar embryonic disc into a trilaminar embryonic disc.
gastrulation
Where does fetal erythropoiesis occur during the 6th to 30th weeks?
liver
Where specifically does spermatogenesis occur?
seminiferous tubules
When does the heart begin to beat and upper and lower limb buds begin to form?
week 4
What does the embryonic ductus arteriosus become after birth?
ligamentum arteriosum
What is the ploidy of a zygote?
diploid
Implantation of blastocyst is present in which week?
1
How many umbilical veins are there?
1
What phase is meiosis II arrested in during oogenesis?
meiosis II is arrested in metaphase until fertilization