Hollow ball with 2 layers

Trophoblast = outside, embryoblast = inside

implants in the uterine wall

2nd to 8th week (day 7-56)

period of rapid growth and differentiation

when differentiation and morphogenesis takes place, the embryo is most susceptible to disturbances at this time

When cells move and develop into something (bones, cells, skin muscle celss etc)

action group of one group of cells on another that leads to the establishment of the developmental pathway in the responding tissue

development of specific tissues and systems

development of specific tissue structure or differing form due to embryonic cell migration

Epiblast and hypoblast layers

suspended between two fluid filled cavities (amniotic cavity)

circular plate of bilayered cell developed from blastocyst

Superior layer in bilaminar disc

composed of high columnar cells

Inferior layer in bilaminar disc

composed of small cuboidal cells

Migratory cells that locate in the middle between the epiblast and hypoblast layers

Embryonic connective tissue

develop in the midline of the floor of the pharynx

Layer in trilaminar embryonic disc derived from EPIBLAST

Top layer

embryonic layer between ectoderm and endoderm

middle layer

layer in trilaminar embryonic disc derived from HYPOBLAST layer

botom layer

membrane at cephalic end

mouth

Membrane at caudal end

anus

*4th week brain and heart growing rapidly

*Oropharyngeal (Buccopharyngeal) membrane sandwich inbetween

*Oropharyngeal membrane lines the stomodeum (primitive mouth) and separates the future oral cavity from the future pharynx

Primitive mouth

little invagination

Growth is initially more rapid than the lower face

it develops by fusion of tissue

Bulge of tissue in the most cephalic end of embryo

gives rise to the upper face, nose, primary palate, eyes and internal ear

are formed when the center of the nasal placodes submerge

they deepen toward the brain

separated from the stomodeum by the oronasal membrane

2 swellings between the nasal pit

grow and fuse to form the middle portion of the nose from the root to philtrum

2 swellings on the outer portion of the nasal pits

grow and fuse to form the alae of the nose

growth from paired medial nasal processes on inside of stomodeum

involved with forming the nasal septum, anterior portion of the palate and maxillary incisors aka globular processes)

forms from the fusion of the 2 medial nasal processes

6 pairs of U-shaped bars of tissue inferior to the stomodeum

formed by crest cells

covered with ectoderm, lined with endoderm with a core of mesenchyme

bilateral, oriented anterior-posterior they bend to surround and supprt the pharynx

formed by the fusion of the 2 mandibular processes in the 4th week

located below the stomodeum

muscles of mastication, suprahyoid muscles, the tongue, and some palatal muscles, trigeminal nerve

swelling that develop from the mandibular arch also during the 4th week

bilateral to the stomodeum, swellings grow superior and anterior

fuse with globular processes of the frontonasal process to form the upper lip and is completed during the 6th week

also forms cheeks along wit the zygomatic bones, secondary palate and posterior portion of the maxilla along with the associated teeth and tissues

failure of fusion of the maxillary processes with the globular process of the medial nasal process

failure to fuse can be unilateral or bilateral, incomplete or complete, more common in boys

between branchial arches

the first one remains becoming the tympanic membrane, others obliterate as the hyoid arch grows inferiorly - results in a smooth neck

forms between 1st and 2nd arches

becomes auditory nerve

remnants of tissue

a disturbance seen when grooves don't become obliterated

formed from the foregut

lined with endoderm

joins stomodeum and the esophagus

outgrowth forms: larynx, trachea, thyroid gland and ends in the superior portion of the lungs