Human Development Flashcards by Ivy Sparlin

What are the stages of human development

Proliferation period (0-3 wks)
Embryonic period (3-8wks)
Fetal development period (9 wks to term)

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Fertilization of ovum yields what?

Zygote

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Mitotic cleavage of zygote forms what?

Blastomeres

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> or = 32 blastomeres is called what?

Morula

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Blastocyst is

64 cell stage morula developed an internal blastocystic cavity.

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A cyst is

any mass that is lined w/ epithelial tissue, hollowed inside or can be filled with a liquid

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Embryoblast is

after the blastocyst developed an inner cell mass at days 6-7

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Implantation of the embryo blast in the uterine wall begins at which day? And is complete at what day?

4 and 10

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Bilaminar embryonic disc is

when the inner cell mass of the embryo blast transitions

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Outer cell mass becomes the cytotrophoblast and syntrophoblast layers which are

precursor to the placenta

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Layers of the bilaminar embryonic disc are

epiblast layer - ectoderm and mesoderm
hypoblast layer - endoderm 
amniotic cavity 
blastocyst cavity
syntrophoblasts
cytotrophoblasts

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Yolk sac is

considered when the Heuser’s membrane will form the internal lining of the blastocyst cavity

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Heuser’s membrane is

when the enlargement of the amniotic cavity and migration of cells out of the hypoblast

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Cell layers

Embryonic cavities during the proliferation period

Epiblast
Embryonic mesoderm
hypoblast

Amniotic
yolk sac
chorionic (containing everything)

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During 3rd wk - the bilaminar embryonic disk is characterized by the formation of what

primitive streak
notochord
neural tube
With the distinct germ layers are - ectoderm, mesoderm, and endoderm

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Primitive streak consists of what

Pit, node, groove

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Primitive node -> _____ _______ -> notochord

notochord process

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Notochord functions as what

primitive skeletal support of the embryo around which the axial skeleton later forms

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Notochord induces the formation of what?

somites, the precursors of the vertebral column, ribs, and associated back muscles and overlying dermis

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describe the process of the formation of the notochord starting with the pre-notochordal cells

Pre-notochordal cells invaginate within the primitive node and migrate towards the cephalad until they reach the prochodal plate. Where they detach themselves from the ectodermal layer to line within the mesoderm

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Derivatives of mesoderm:

paraxial mesoderm ->
Intermediate mesoderm ->
Lateral plate mesoderm:
- parietal mesoderm ->
- visceral mesoderm ->

Somites
Urogenital system
- Mesothelial (serous) membranes that cover the peritoneal, pleural and pericardial cavities
- Forms the thin serous membranes that cover individual organs like stomach, pancreas, spleen, etc.

Derivatives of ectoderm:

Epidermis, hair and nails,
Epithelium of the oral and nasal cavities and paranasal sinuses,
Salivary and endocrine glands,
Nervous system,
Tooth enamel

Derivatives of Endoderm

GI tract epithelium and associated glands

What does the neural tube make?

Spinal cord

Spina bifida is caused by?

Neural tube defects bc - folic acid deficiency | Mild defect

Meningocele is caused by?

Neural tube defects bc - extrusion of dura and arachnoid mater Mild defect

Meningomyelocele is caused by?

Neural tube defects bc - Extrusion of neural tissue plus all 3 meninges More severe defect

Anencephaly is caused by?

Fatal defect characterized by lack of development of the cranium and brain

Meningoencephalocele is caused by?

Neural tube defects bc - Extrustion of a ventricular cistern plus neural tissue More severe

Neural crest cells AKA

ectomesenchyme and neuroectoderm

Neck - ear is made by

branchial/pharyngeal arches (rings)

1st branchial groove -> | 1st branchial pouch ->

External auditory canal | Eustachian tube

2nd branchial pouch ->

palatine tonsils

3rd branchial pouch ->

inferior parathyroids/thymus

4th branchial pouch ->

superior parathyroids/ultimobranchial body

The head _____ to the relative proportions of the body after 3 months

decreases.

Development of the face consists of what processes

mandibular, maxillary, lateral nasal, and median nasal

Cleft lip is

defective fusion of medial nasal processes with the maxillary process. Normally occurs at 5-6 wks

Cleft palate is

Defective fusion of the palatine shelves. Fusion of the palatine shelves normally begins during the 8th wk of gestation and is completed by the 12th wk

Cleft palate is

Defective fusion of the palatine shelves. Fusion of the palatine shelves normally begins during the 8th wk of gestation and is completed by the 12th wk

If one child is born with a cleft lip, what are the odds the second child has the same defect?

40%

Known teratogens involved in congenital malformations

Drugs - ethanol, tetracycline, dilanitin, lithium, methotrexate, warfarin, thalidomide, androgens, progesterone, retinoic acid Chemicals - methylmercury and polychlorinated biphenyls Radiation - high levels of ionizing radiaiton

Nasopalatine duct cyst develops where

at line of fusion btw palatine shelves and primary plate

What is a lateral cervical cyst/branchial fistula?

Where the cervical sinus remains past 7th wk

Branchial arch #1 - intermediate structure - adult structure - cranial n. - Tongue structure

Median tongue bud, forament cecum, and lateral lingual swellings Overgrown by lateral lingual swellings, origin of the thyroid ectoderm, and anterior 2/3 of the tongue Trigeminal Sensory to the anterior 2/3

Branchial Arch #2 - intermediate structure - adult structure - cranial n. - Tongue structure

Copula/tuberculum Impar Overgrown by the hypobranchial eminence Facial Special sensory (taste) to anterior 2/3 via the chordates tympani branch

Branchial Arch #3 - intermediate structure - adult structure - cranial n. - Tongue structure

hypobranchial eminence posterior 1/3 of the tongue Glossopharyngeal Sensory to the posterior 1/3

Branchial Arch #4 - intermediate structure - adult structure - cranial n. - Tongue structure

Minor contributions to the hypobranchial eminence None Hypoglossal Motor to all the tongue muscles

Thyroglossal Duct cyst is

failure of throglossal duct to involve causing cyst, can get caught in all of the spaces as it moves down like hyoid bone, thyroid cartilage etc

branchial arch cartilage

Meckel's cartilage (mandible maleus, and incus), Reichart's cartilage (Stapes, styloid process, stylohyoid process, stylohyoid ligament, lesser horn of hyoid), Greater horn of hyoid, and thyroid cartilage