Weeks 1-4 Flashcards
After fertilization, how long after does birth take place? How long after the onset of the last menstrual period
38 weeks; 40 weeks
Premature refers to babies born before
37 weeks from the onset of the last menstraul period.
35 weeks from fertilization
Babe tween 37 and 40 weeks from the onset of LMP is known as
Term
The development in the embryo is divided into 3 stages. What re they?
Germinal (pre embryonic)
Embryonic
Fetal
The germinal period lasts
2 Weeks
The embryonic period is between weeks
3-8
The organ systems begin to develop During the _______period
Embryonic
Formation of the bilaminar germ disk happens during the
Germinal period
The highest sensitivity of to congenital malformation (physical birth defect) is during which period
Embryonic
The cranial position of a fetus refers to
The head
The dorsal position refers to
The spine
The caudal position refers to the
Tail
The ventral position refers to the
Front
Fertilization usually occurs in the_______of the Fallopian tube
Ampullae region
With each mitotic division of the zygote, each divided cell and gets smaller and smaller and are called
Blastomeres
The membrane which keeps the zygote the same size despite the mitotic divisions is called the
Zoma pellucida
The blastomeres and the zona pellucida are collectively called
The morula
The outer cell mass of the morulais also called the_______and will give rise to the fetal portion of the
Trophoblasts
The inner cell mass of the morula is also called the______since it is where the embryo will form
Embryoblast
Prior to implantation, the trophoblasts (outer mass) differentiates into
Cystotrophoblasts
Syncytiotrophoblasts
The uterine epithelium is invaded by the________which initiates implantation
Syncytiotroblasts
The blastocyst will implant on the_______of the uterus by end of day 6
Posterior superior
Ectopic pregnancy happens when when the fertilized egg
Grows outside of the uterus
The most common ectopic pregnancies is when the uterus grows in the
Fallopian tubes
Tubal pregnancies has signs similar to
Normal pregnancy
Tubal pregnancies if left untreated can cause the Fallopian tube to
Rupture
Early ectopic pregnancies can be treated with medication called methotrexate _______which essentially kills the zygote
Late diagnosis of ectopic pregnancies are treated
Surgically
The bilaminar germ disc is formed by
Week 2
The space which becomes the bilaminar germ disc are occupied by 2 types of cells. What are they
Epiblast
Hypoblast
Spaces formed within the syncyttiotropoblasts which allow blood vessels of the mother to fill are called
Trophoblastic lacunae
This membrane protects the embryo
Amniotic membrane
The bilaminar germ disc is suspended with the_______above it and the_______below it
Amniotic cavity; primitive yolk sac
When the extraembryonic cavity dissociates, the outer space surrounding the embryo is now called
Chorionic cavity
Gastrulation begins by the end of
Week 2
Gastrulation starts with the formation of the
Primitive streak
These cells migrate through the primitive streak
Epiblasts
After the formation of the primitive streak, the epiblasts invades and replaces these cells
Hypoblasts
The mesoderm is divided into 3 sections, composing of 2 of each. What are they
Paraxial
Intermediate
Lateral
The intermediate mesoderm forms the
Kidneys and gonads
The lateral mesoderm splits into
Somatic and Splanchnic mesoderms
Somatic mesoderms form the
Parietal Serosa
Dermis of ventral body region
Connective tissues of limbs
The splanchnic mesoderm forms the
Heart
Blood vessels
Wall of digestive and repertory tracts
The endoderm forms the
Epithelial lining and glands of digestive and respiratory tracts
Ectoderm forms the
Epidermis
Hair
Nails
Brain and spinal cord
Neural crest
The outer ectoderm forms
Hair
Nails
Mouth epithelium
Lens, cornea
The neural crest of the ectoderm forms the
Peripheral nervous system Adrenal medulla
Melanocytes
Facial cartilage
Denting of teeth
Neural tube
Brain
Neural pituitary
Spinal cord
Motor neurons
Retina
Neurulation happens by the embryonic formation of the________by closure of the________
Neural tube; neural plate
The neural plate is formed from the
Overlying ectoderm
Which neuropore closes first?
Anterior
Posterior
Posterior
In Gastrulation, the hypoblast turns into
Endoderm
In Gastrulation, the the epiblasts turn into
The ectoderm
Implantation occurs with the syncytiotrophoblasts degrades the ___________of the uterus
Endometrium
The blastocyst is composed of which cells
Epiblasts and hypoblasts
The prechordial plate consist of which cells
Epiblasts and hypoblasts
a characteristic feature/happening during the 2nd week of
development is the
Lacunae spaces formed within the syncytiotrophoblast
The secondary yolk sac is formed by the end of
Week 2
Gastrulation begins by the end of
Week 2
The process of a zygote developing into increasingly smaller blastomeres is known as
Cleavage
Gastrulation is the formation of the
Trilaminar germ disc
This structure surrounds the cells after fertilization as they compact to form the morula
Zona pellucida
Implantation occurs on which day post fertilization
Day 6
In the 3rd and 4th week of development, the endoderm layer lines the
GI tract in the stomach
This germ layer forms the epithelial lining of the of the intestines
Endoderm
Hypoblast cells displace into the
Secondary yolk sac
Folic acid intake during pregnancy can prevent
Spina bifida
Sirenomelia (mermaid syndrome) is caused by a loss of __________in the lumbar sacral region
Mesoderm
Failure of The posterior neuropore closing leads to
Spina bifida
Anencephaly (deflated head) is caused by the____________not closing
Anterior neuropore not closing
Birth takes place__________weeks after the onset of the last menstrual cycle, or___________weeks after fertilization
40;38
Development of the fetus develops_________to_________
Cranially;caudally
The notochord is derived from the folding of the
Endoderm
