chapter 17 terms Flashcards
derived primarily from surface ectoderm
epidermis
surface layer of non-keratinized squamous cells
periderm
waxy coating of fetal skin
vernix caseosa
created by proliferation of cells of stratum basale»_space; genetically determined and give rise to “prints”
dermal ridges
general term for a group of hyper-keratinization disorders»_space; dry, fish-like scaling of skin
ichthyosis
genetic recessive trait where skin and hairs lack pigment
albinism
genetic dominant trait resulting in patches of albinism
piebaldism
formed from lateral somatic mesoderm and from dermatomes of somites
dermis
benign skin tumors resulting from the overgrowth of small blood vessels »_space; typically enlarge for a few months after birth and then shrink and disappear by 5-10 years
infantile angiomas
dermal root sheath and hair papilla
mesenchymal additions
migrate into hair bulbs and differentiate into melanocytes»_space; transfer melanin into hair forming cells
melanoblasts
develop as buds off the sides developing epidermal root sheaths »_space; branch to form lobes
sebaceous glands
develop as epidermal down-growths into underlying mesenchyme
eccrine sweat glands
develop similar to eccrine glands except initiate from hair buds
apocrine sweat glands
develop as modified/specialized sweat glands»_space; evaginations of epidermis at 6 weeks
mammary glands
thickened strips of ectoderm from which mammary glands develop»_space; appear in week 4 and normally persist only in pectoral region
mammary crests
excessive development of mammary glands in males
gynomastia
supernumerary breasts
polymastia
supernumerary nipples
polythelia
develop from oral ectoderm and neural crest derived mesenchyme
deciduous and permanent teeth
initiated by neural crest mesenchyme
odontogenesis
each tooth bud invaded by mesenchyme
cap stage
junction on inner and outer enamel epithelia»_space; induces odontoblasts to form root of tooth
results in narrowing of pulp cavity + formation of root canal to allow passage of nerves and vessels
epithelial root sheath
condensation of mesenchyme surrounding developing tooth
dental sac
present at birth»_space; painful nursing, lacerate tongue or can fall out and be aspirated
natal teeth
results in pits and/or fissures in teeth
underlying causes = rickets, tetracycline, infectious diseases and idiopathic
enamel hypoplasia
spherical masses of enamel formed by aberrant masses of ameloblasts
enamel pearls
supernumerary teeth that develop in area of maxillary incisors»_space; may disrupt eruption or position of normal teeth
mesiodens
one or more teeth absent»_space; familial trait
partial anodontia
rare condition resulting from congenital ectodermal dysplasia
complete anodontia
fusion of two adjacent teeth (most common) or partial splitting of a single tooth during development
macrodontia
yellowish/brown teeth resulting from hypocalcification of enamel»_space; dominant inheritance
ameliogenesis imperfecta
brown or bluish gray teeth resulting from hypocalcification of dentin
dentiogenesis imperfecta
foreign materials incorporated into forming enamel
discolored teeth
blue/black teeth due to incorporation of hemoglobin
hemolytic disease of newborns
results in greenish teeth
hyper bilirubinemia
maternal use can result in brown/yellow coloring of teeth
tetracyclines
