3018 Quiz 2 (Prenatal & Facial Development)

What is the study of prenatal development?

Embryology

What begins with the start of pregnancy and continues until birth of the child?

Prenatal development

What is the first period of prenatal development?

Preimplantation period

When is the preimplantation period?

First week after conception

What is the union of the ovum and sperm; fertilized egg?

Zygote

What is the display of a person's chromosomes with the sex known by XX for a woman and XY for a man?

Karyotype

What is the solid ball of cells after initial cleavage of zygote?

Morula

What does morula become after secretion of fluid in the morula?

Blastocyst

When is the embryonic period?

Second week to end of eighth week

What is controlled levels of cellular growth present during most of prenatal development?

Proliferation

During the second week, what is the increased number of embryonic cells?

Embryonic cell layers

What does the bilaminar embryonic disc consist of?

Epiblast layer and hypoblast layer

What fluid filled cavity faces the epiblast?

Amniotic cavity

What fluid filled cavity faces the hypoblast?

Yolk sac

What does bilaminar embryonic disc develop into later?

Embryo

During third week, what forms within the bilaminar disc?

Primitive streak

What does the primitive streak cause the disc to have?

Bilateral symmetry

What do the migratory cells located between epiblast and hypoblast become?

Mesoderm and endoderm

What does the bilaminar embryonic disc thicken into?

Trilaminar embryonic disc

What does epiblast turn into?

Ectoderm

What does hypoblast turn into?

Endoderm

What makes a disc?

Three germ layers

What are the parts of a disc?

Cephalic (head end) and caudal (tail end)

What group of cells differentiate from the ectoderm?

Neuroectoderm

When does the CNS develop?

Latter part of 3rd week

What forms from the neuroectoderm?

Neural system

Where are the neuroectoderm cells located?

In the neural folds

What is a central band of cells that extends the length of the embryo?

Neural plate

What undergoes further growth and thickening, which causes it to deepen and invaginate inward forming the neural groove?

Neural plate

What does the neural plate form when it thickens and deepens?

Neural groove

Near the end of the third week, what deepens further and is surrounded by the neural folds?

Neural groove

What does further growth of the neuroectoderm form?

Neural tube

What is formed during the fourth week by the neural folds undergoing fusion?

Neural tube

What forms the future spinal cord?

Neural tube

What is the process of growth from the neuroectoderm?

1. Neuroectoderm is located in the neural folds

2. Neural plate thickens and folds inward, forming neural groove

3. Neural groove deepens inward and is surrounded by neural folds

4. Neural folds fuse together and form neural tube

What develops from neuroectoderm?

Neural crest cells

Where do neural crest cells migrate?

Toward mesenchyme

When neural crest cells differentiate, they help develop what?

Face, neck, and oral tissues

What divides into 38 paired blocks on each side of the midline portion of CNS?

Mesoderm

What are blocks of mesoderm?

Somites

During the 4th week, what does the disc undergo?

Embryonic folding

After the folding, where does endoderm lie?

Inside of ectoderm

What is considered to be fourth embryonic cell layer?

Neural crest cells

What fills the area between the two layers?

Mesoderm

What is one long tube form from embryonic folding and is lined by endoderm?

Future GI tract

Chapter 4

Facial Development

What is the primitive mouth that forms at the beginning of the 4th week?

Stomodeum

What are two bulges that appear inferior to the mouth?

Mandibular processes

What fuses at the midline to become the mandibular arch?

Mandibular processes

What is another name for mandibular arch?

Branchial arch I

What is cartilage that forms on each side of the mandibular arch?

Meckel's Cartilage

What does the mandibular arch eventually develop into?

Mandible, lower lip, mandibular teeth, muscles of mastication, etc

What are two adjacent swellings that occur from each side of the mandibular arch?

Maxillary processes

What will the maxillary processes help form?

Upper lip, cheeks, secondary palate, most of the mid-face, posterior maxillary teeth and canines

How is upper lip formed?

Fusion between maxillary process and medial nasal process

What is a bulge of tissue in the upper facial area?

Frontonasal process

What does the frontonasal process form?

Forehead and midline and nose area

What are rounded areas of thickened ectoderm found at the location of the developing sense?

Placodes

What are some types of placodes?

Nasal, lens, otic

What fuses externally to help form the upper lip and middle part of the nose (philtrum)?

Two medial nasal processes

What happens when one side of maxillary process does not fuse with the medial nasal process?

Unilateral cleft lip

What happens when both sides of maxillary process does not fuse with the medial nasal process?

Bilateral cleft lip

What fuses internally to form the intermaxillary segment (premaxilla, primary palate)?

Medial nasal process

What will help form maxillary incisor teeth and adjacent teeth?

Intermaxillary segment

What will form the primary palate and part of the nasal septum?

Intermaxillary segment

What will help form the ala of the nose?

Lateral nasal processes

What does the endoderm line?

Developing branchial arches and pharyngeal pouches

What does each paired arch have?

Its own developing cartilage, nerve, vascular, and muscular components

What is 2nd branchial arch called?

Hyoid arch

What is each arch separated by?

Branchial grooves externally and pharyngeal pouches internally

What is the 2nd arch cartilage?

Reichart's cartilage