module 8 - prenatal development and face and neck development

embryology

the study of prenatal development

preimplantation period

first week —> zygote and blastocyte

embryonic period

2-8 weeks —> disc, embryo, folded embryo

fetal period

3-8 months —> embryo and fetus

primordium

earliest recognizable structure

developmental disturbances

can happen at any point in development —> caused by genetic factors or environmental agents

what is this

flexion

what is this

dilaceration

what is this

concrescence

what is this

fusion

teratogens

environmental agents and factors involved in developmental disturbances —> infections, drugs, radiation

karyotype

organized profile of an individual chromosome

phenotype

an organism’s physical appearance, or visible traits

morula

after initial cleavage — solid mass of cells, all have contact with outside

blastocyst

morula continue to divide — layers within

end of preimplantation period week 1

blastocyst implants into endometrium

trophoblast layer

layer of peripheral cells of blastocyst

peripheral cells

involved in forming prenatal support tissue

embryoblast layer

inner mass of embryonic cells — involved in forming embryo

induction

action of group of cells on another to change

differentiate

act of becoming different cells

proliferation

controlled cellular growth

appositional growth

growth by adding layers to the outside — think of a tree

interstitial growth

growth happening from within

what happens during embryonic period

differentiation and morphogenesis

morphogenesis

cells and tissue organize into specialized structures

embryonic period week 2

starting point — blastocyst has been implanted

embryonic cell layer

from within blastocyst

bilaminar embryonic disc

form embryoblast layer — becomes the fetus

bilaminar embryonic disc layers

1. superior epiblast layer

2. inferior hypoblast layer

primitive streak

the groove where cells move in

when do layers become endoderm and ectoderm

embryonic period week 3

ectoderm

involved in skin epidermis, central nervous system and other structures

mesoderm

involved in formation of connective tissue like cartilage, bone, blood, and muscle

endoderm

involved in formation of respiratory epithelium and cells of glands

cephalic end

head

where does the oropharyngeal membrane form

cephalic end (head)

stomodeum

mouth of future embryo — beginning of digestive tract

caudal end

tail

where is the primial streak

caudal end

invagination

folding in onitself

neural crest cells

send messages to different parts of the body

what happens during embryonic folding

endoderm ends up inside ectoderm with mesoderm

what develops during week 4

• face and neck

• ears, eyes, oral cavity, jaw

when does facial development start

4th week

when is facial development complete

12th week

facial fusion

either by fusion of same surface or fusion of different surfaces