Human Embryology 2 - Development Of Head & Face Flashcards
Fetal membrane composed of
- Chorion
- Amnion
- Yolk sac
- Allantois
- Umbilical cord
Chorion has three phases of villi
- Primary
- Secondary
- Tertiary
In the Decidua capsularis, there is pressure, so overtime the villi in that area of the embryo differentiate into a smooth surface called
Chorion laevae
In the Decidua basalis, there is minimal pressure at that end of the embryo and abundant nutrition, so the villi there grow and branch into
Chorion frondosum
Chorion frondosum participates in the formation of the
Placenta
The placenta of the Decidua basalis comes from the ______ in fetal development
Mother
The placenta of the chorion frondosum comes from the ______ in fetal development
Fetus
Amniotic fluid is renewed every _______ hours
3
Yolk sac composed of
- Inner Endoderm
- Outer Extraembryonic Mesoderm
Endoderm cells of the yolk sac form ______ which differentiate into spermatogonia and oogonia
Primordial germ cells
Mesoderm cells of the walls of the yolk sac differentiate into
Blood island, primary blood vessels & primitive blood cells
Outpocketing of the embryo’s gut
Allantois
The umbilical cord is about
50cm long
Structure by which exchange of material between fetus and mother occurs
Placenta
Structures of the placenta
Maternal portion
Decidua basalis
Structure of the placenta
Fetal portion
Chorion frondosum
The structure between fetal and maternal blood
Placental barrier
Placental barrier is comprised of
- Endothelium
- Connective tissue
- Cytotrophoblast
- Synctiotrophoblast
Functions of placenta
- Exchange
- Protection
- Hormone production
- (HCG) Human Chorionic Gonadotropin
- (HPL) Human Placental Lactogen
- Progesterone
- Estrogen
HCG is produced in abundance _____ weeks after fertilization
2
Week 4-5 symmetrical columns formed called
6 pairs
Brachial arches
Between brachial arches
Brachial clefts
Cranial part of the foregut formed from the endoderm
Primitive pharynx
At week 4, the neural crest mesenchyme produces five (5) principal prominences named
- Frontonasal prominence
- Heart prominence
- Maximally prominence (pair)
- Mandibular prominence (pair)
- All surrounding a Stomodeum
Anterior 4 pairs of brachial arches are
Visible
The 5th pair of brachial arches
Disappear
The 6th pair of brachial arches is
Not visible
Brachial apparatus comprised of
- Brachial arches
- Brachial cleft
- Brachial membrane
- Pharyngeal pouches
Base of the Stomodeum
Oropharyngeal membrane
By week 6, two additional prominences formed
- Lateral nasal prominence (pair)
- Medial nasal prominence (pair)
Medial nasal prominence forms
- Philtrum
- Medial upper lip
- Nasal tip
- Columella
Lateral nasal prominence forms
- Lateral nasal ala
- Nasolacrimal groove
The formation of the palate occurs between
Week 5 - Week 12
The frontonasal prominence forms
- Forehead
- Bridge and tip of nose
- Philtrum
- Primary palate
The maxillary prominence forms
- Lateral part of upper lips
- Lateral wall and floor of orbit
The mandibular prominence forms
- Mandible
- Lower lip
Malformations of the prominences
very important for exams
- Bilateral cleft lip
- Oblique facial cleft
- Cleft lip
4.