Histology and Embryology Flashcards
Preimplantation Period
first week of conception
Embryonic Period
weeks 2 to 8
Fetal Period
weeks 9 to birth
Fertilization Stage
Preimplantation
formation of zygote
zygote receives 23 chromosomes from mom and 23 from dad
zygote undergoes mitosis and eventually becomes a blastocyst
Implantation
Preimplantation Period
by 7 days, the blastocyst will be endometrium
after one week, it will consist of a trophoblast layer (nutritive) and a embroblast layer (becomes embryo)
Bilaminar Disk
Embryonic Period
consists of a superior epiblast layer and an inferior hypoblast layer
disc is suspended between 2 spaces - the amniotic cavity and the yolk sac
Trilaminar Disk
Embryonic Period
Consists of Mesenchyme, Ectoderm, Mesoderm, Endoderm
Mesenchyme Layer
differentiates into different connective tissue
(odontoblasts, osteoblast, fibroblast ect)
Ectoderm
forms the epithelial enamel organ
(week 3 of embryonic period)
Mesoderm
forms during embryonic period
forms the dental papillae which differentiates into dental pulp and elaborates the dentin
called the dental sac
forms the cementum covering the root and periodontal membranes
Endoderm
forms during embryonic period
forms epithelial linings of the respiratory passages and digestive tract
Embryonic Folding
Last stage of Embryonic Period (end of week 9)
most organs and body systems are developed
most congenital malformation occurs in this stage
enlargement of embryo into a fetus
Period of Face Development
Weeks 3-12
First Brachial Arch
AKA Mandibular Arch
Divides into maxillary and mandibular processes
Mandibular Process
Lower parts of the face and lower lip
anterior ⅔’s of the tongue
What forms the posterior ⅓rd of the tongue and the hyoid bone?
Second and third brachial arches
Maxillary Process
Lateral palatine processes
upper parts of cheek
sides of upper lip (not philtrum)
Frontal Process
forhead and frontal bone
Median Nasal Process
Center and tip of nose
nasal septum
globular process (philtrum, premaxillary palate (anterior) )
Lateral Nasal Process
sides of nose
infraorbital area
Stomodeum
primitive mouth
lined by ectoderm, which will become oral epithelium
mesoderm differentiates into ectomesenchyme
Week 3
Period of Tongue Formation
Develops weeks 4 to 8
Filiform Papillae
- *only papillae with no taste buds**
- keratinized*
elongation known as hairy tongue
Fungiform Papillae
Few, large red bumps
contain taste buds
Foliate Papillae
folds of tissue at posterior, lateral boarder
contain taste buds
Circumvallate Papillae
8-12 in number
anterior to the sulcus terminalis
contains taste buds and glands of Von Ebner
Tongue Innervation
Hypoglossal: motor nerve
Trigeminal V3: sensory to anterior ⅔
Facial: taste to anterior ⅔ (via chorda tympani)
Glossopharyngeal: taste and sensory posterior ⅓