Prenatal Development

sperm + egg = zygote

cell division of the zygote (which then = blastocyst)

the collection of cells after zygote division

migrates from the fallopian tubes to the uterus

blastocyst becomes embedded in the endometrium (uterine wall) and continues to divide

Ectopic Pregnancy can occur if the blastocyst implants anywhere (fallopian tube) BUT the uterus

• TROPHOBLAST LAYER: outside cells that will eventually become the prenatal support tissues
• (ie: placenta and umbilical cord circulation)

EMBRYOBLAST LAYER: inner cells that will become the embryo

second to eighth week

unknown; "lets get started" (pow wow)

• controlled levels of cellular growth (uncontrolled = cancer)
• Interstitial and Appositional

growth from within (blowing up a balloon) cells filled from the inside to outside

• growing by layers (paper mache).
• grows from the outside

• when cells start to be structurally and functionally different and become tissues
• Cytodifferentiation
• Histodifferentiation
• Morphodifferentiation

• development of different cells (cyto=cell)
• i.e. heart and muscle

• development of different tissues in a structure i.e. valve, pump (heart)
• (histo=tissue)

the tissues start to become structures (morpho=structures)

• growing up in form, function, and size
• if this goes wrong = miscarriage

• forms in the second week it is the two layer epiblast (top) and hypoblast (lower) meeting point of two fluid filled cavities
• Amniotic Cavity
• Yolk Sac

faces the epiblast layer

faces the hypoblast layer and serves as the initial nourishment for the embryonic disc

• forms from the trophoblast layer and the endometrium. This and the developing umbilical circulation system permit selective exchange of soluble bloodborne substances between the woman and the embryo.
• Syphillis
• Fetal Alcohol Syndrome
• Tetracycline

• std can cross through BV's to baby.
• Hutchinsons Incisors
• Mullberry Molars Occur

causes learning disabilities

• Staining intrinsic and never goes away
• Teteracycline binds to the dentin.
• The lines on the teeth determine when the mother was taking tetracycline during pregnancy

• forms in week three
• A thickening of cells that splits the disc in half. The right and left sides will be symmetrical.
• (bum)

• formed when some migratory cells from the epiblast layer move towards the hypoblast layer and they get caught in the middle.
• this new layer = Trilaminar Embryonic Disc leading to new names for all the layers.

• Came from epiblast (pink playdoh)
• Epidermis
• Sensory epithelium of the eyes, ears, and nose (senses)
• Nervous System
• Neural Crest Cells
• *Ectodermal displasia can occur

the mesenchyme-or layer that tried to migrate and got stuck between the layers. (middle-green)

• Ectoderm "outside" pink
• Mesoderm "middle" green
• Hypoblast layer "inside" orange

• Dermis
• Connective Tissue
• Muscle
• Bone
• Lymphatics
• Blood Cells
• Bone Marrow
• Cartilage
• Reproductive Organs
• Excretory Organs

• Epidermis
• Sensory Epithelium of the eyes, ears, and nose (senses)
• Nervous System
• Neural Crest Cells

• abnormal development of the ectoderm. NOT meso or endo
• Affects:
• Teeth
• Skin
• Hair
• Nails
• Facial Structure
• Glands
• (hereditary)

• Cephalic end
• Caudal end
• both part of the digestive tract
• ONLY ecto and endo. NO meso

• head end
• the wide part of the shoe
• oropharyngeal (mouth) membrane formed here
• primitive mouth and beginning of the digestive tract

• tail end
• the narrow part of the shoe
• the cloacal membrane (anus) formed here
• anus and terminal end of the digestive tract

• "orange playdoh"
• Hypoblast layer
• gives rise to the inside
• 1) respiratory system linings
• 2) digestive system linings
• 3) liver cells
• 4) pancreatic cells

• Neurectoderm
• Neural Plate
• Neural Groove
• Neural Fold
• Neural Tube

• differentiates from the ectoderm
• streak deepens and goes down to the cloacal membrane

• where all the neuroectoderm hang out.
• a band of cells that extends the length of the embryo from the cephalic to caudal end.

• when the plate thickens with cells and deepens into the embryo
• it then sinks deeper to neural folds and eventually to a neural tube
• this tube fuses and become the spinal cord

• when the tube doesn't form completely
• cord and fluid bubble out and sometimes paralyzes the child

folic acid (vit b9 helps with fusion) is the prenatal vitamin that can prevent spina bifida, cleft palate and cleft lip

• develop form the neuroectoderm
• give rise to:
• 1) connective tissue
• 2) cartilage
• 3) bone
• 4) dental tissues

• 38 paired blocks of mesoderm along both sides of the neural tube
• gives rise to skin and bones of the neck and trunk

• folding occurs
• might know you are pregnant

• the disc starts to fold-establishing the human axis and placing the tissues in their proper positions for further development
• 1) endoderm is at the core
• 2) ectoderm is on the outside
• 3) mesoderm is in the middle

• one hollow tube that will be the digestive tract
• 1) foregut
• 2) midgut
• 3) hindgut

• anterior section of the tube
• forms the throat

• middle section of the tube
• forms the rest of the digestive tract

• posterior section of the tube
• forms the rest of the digestive tract

• face
• neck
• oral structures

• Third to Ninth month
• time of maturation
• allows newly formed tissues and organs to function

• fourth month
• detect heartbeat and fetal movements