Gross Test 1 Early Human Development

Front 1

what happens in the first week

Back 1

1. ovulation

2. fertilization

3. development during embryo transport (pre implantaion )

Front 2

ovulation process

Back 2

1.the ovum (secondary oocyte) is released from a mature ovarian follicle

2. ovum, surrounded by zona pellucida (mucopolysaccharide shell) and corona radiata (follicular cells of cumulus oophorus) is swept through peritoneal cavity and into uterine tube

Front 3

fertilizaiton process

Back 3

def: joining of sperm and egg

usual site of fertilization is the ampulla of the uterine tube

penetration of external barriers of ovum ( zona pellucida and corona radiata ) by sperm , followed by the union of pronuclei

Main results for this :

- restoration of diplaoid number of chromosomes

-determines sex

-and initiation of clevage

Front 4

pre implantaion process

Back 4

at day 4 the morula forms :

- cleavage is happening

-a 12- 16 cell stage

- cells called blastomeres

- resemble mulberry ( hence the name)

- surrounded by zona pellucida

at day 5 the blastocyte forms :

- intercelluar clefts coalesce to form central cavity

- blastocyst cavity enclosed by blastomeres

- zona pellucida dissapears ( hatching)

- two cell types are distinguishable = earliest cell differentiation

Front 5

the two cell types that are distinguishable in the blastocyte are

Back 5

1. trophoblast= outer cell layer

- flattened epithlioid cells

- form wall of blastocyst cavity

- will form fetal componenet of placenta

2. embryoblast= inner cell mass

- cuboidal cells

- located at one pole of blastocyst

- will form the body of the embryo

Front 6

what happens in the second week

Back 6

1. implantaion

2. subdivions of the trophoblast

3. inner cell mass forms bilaminar disk

4. amnion

5. primary umbilical vesicle

6. extraembryonic mesoderm

7. extraembryonic coelom

Front 7

implantaion process

Back 7

by day 12 COMPLETE :

def= process by which the free-floating blastocyst adheres to and penetrates the endometrial lining of the uterus

duration = day 6- day 12

process =

1. trophoblastic blastomeres are sticky

2. trophoblast destroys endometrial cells

3. trophoblast proliferates and invades

Front 8

subdivions of trophoblast process

Back 8

subdivides into :

1. cytotrophoblast

2. syncytiotrophoblast

Front 9

features of the cytotrophoblast

Back 9

-mononucleated epithelial cells

-seperated by distinct cel boundaries

- surrounds blastocyst cavity

Front 10

features of the syncytiotrophblast

Back 10

- multinucleated protplasmic mass

- lacks complete cell boundaries

- extends outward from cytotrophoblast

Front 11

inner cell mass forms bilaminar disk process

Back 11

splits and forms :

1. epiblast - tall columnar cells , which give rise to body of embryo and to amnion

2. hypoblast- cuboidal cells, which give rise to endoderm of umbilical vesicle

Front 12

amnion process

Back 12

1. intercellualr clefts appear within the epiblast

2. clefts coalesce to form amniotic cavity DAY 8

Front 13

primary umbilical vesicle process

Back 13

1. outgrowth of flattened cells from the periphery of hypoblast

2. lines blastocyst cavity

3. converted to secodary umbilical vesicle ( definitive yolk sac)

Front 14

extraembryonic mesoderm process

Back 14

1. loose array of cells initialy derived from the hypoblast

2. situated external to amnion and to yolk sac

Front 15

extraembryonic coelom

Back 15

- clefts develope between extraembryonic mesodermal cells

- clefts coalesce to form a cavity, lined by extraembryonic mesodem , will eventually be obliterated by growth of fetus

Front 16

what happens in the third week

Back 16

- formation of trilaminar disk

- further development of trilaminar disk

Front 17

during the formation of the trilaminar disk what happenes

Back 17

1. primitive streak forms ( day 15 )

2. gastrulation

Front 18

primitive streak process

Back 18

- appears as median groove at caudal (tail) end of epiblast

- primitive node is expanded cranial(head) end of primitive streak

Front 19

grastrulation process

Back 19

- epiblast cells migrate and invaginate at primitive groove and primative pit

-epiblast cells that invaginate through primitive groove and primitive pit become :

1. embryonic endoderm-laterally displaces

cells of the hypoblast , will form

epithelium of the primitive gut

2. embryonic mesoderm- occupies space

between epiblast and endoderm, migrate

laterally and cranially from primitive

streak

- epiblast cellls that do not invaginate become embryonic ectoderm

1. develops into nervous system and

epidermis

2. surrounds mesoderm and endoderm

Front 20

what happens with further development of the trimalminar disk

Back 20

1. precordal plate is formed ( day 14 )

2. notochord

3. initiation of neural development

4. subdivision of mesoderm

5. intraembryonic coelom

6. body folding

Front 21

precordal plate

Back 21

formed DAY 14 :

-circular area of firm attachement of ectoderm and endoderm

- identifies cranial end of embryo

- precursor of buccopharyngeal membrane and primitive mouth

- secretes molecular signals required to pattern head of embryo

Front 22

look at chart

Back 22

of how hypoblast and epiblast form

Front 23

notochord is formed how and does what

Back 23

it is a median mesodrmal "rod" that forms from the cells invaginating through the primitive pit

it identifies the cranial and caudal axis of embryo

it breaks up into segments to form core ( nucleus pulposus of intervertebral discs

and it seretes molecular signlas required to initiate development of nervous system

Front 24

what are formed during the initiation of neural development

Back 24

1. morphogenisis of the neural tube (neurulation)

2. differentiation of the neural tube at level f spinal cord

Front 25

process of morphogenisis of the neural tube ( neuralation )

Back 25

1. the nueral plate formation

2. neural groove formation

3. neural tube formation

4. nerual crest formation

Front 26

neural plate

Back 26

forms from ectoderm cells that proliferate and change shape

elevated edges form the neural folds

induced by underlying notochord

Front 27

neural groove

Back 27

produced by folding of neural plate

median v shaped , axial depresion in neural plate

Front 28

neural tube

Back 28

formed by midline fusion of the neural folds

seperates from the adjacent surface ectoderm

forms central nervous system ( brain and spinal cord)

Front 29

neurual crest

Back 29

cells derived from neural folds as the neural tube closes

Front 30

derivatives of the neural crest

Back 30

- neurons of dorsal root and cranial sensory ganglia

- schwann and satallite cells of peripheral nerves and ganglia

- neurons of sympathetic and parasympathetic ganglia

- bone and cartilage derivatives of pharyngeal arches

Front 31

differentiation of the neural tube at level of spinal cord layers and thier derivatives

Back 31

1. neuroeipthelium - ependyma

2. mantle layer- gray matter

3. marginal layer- white matter

Front 32

differntiation of the neural tube at level of spinal cord plates and thier derivatives

Back 32

1.roof plate

2. alar plate- sensory (afferent)

3. basal plate - motor ( efferent)

4. floor plate

Front 33

subdivisions of the mesoderm

Back 33

1. paraxial mesoderm

2. intermediate mesoderm

3. lateral plate mesoderm

Front 34

what does thr paraxial mesoderm do

Back 34

1. breaks into paired segmental blocks called somites

2. forms adjacent to notochord

3. somites form vertebrae , dermis of the skin of the back , and most skeletal muscles of the body

Front 35

what does the intermediate mesoderm do

Back 35

1. cels immediatly lateral to somites

2. forms nephrogenic cord and genital ridge

Front 36

what does the lateral plate mesoderm do

Back 36

1. somatic or parietal layer - associated with ectoderm , "outer" lining of body cavity

2. splanchinic or visceral layer - associated with endoderm , "inner" lining of body cavity

Front 37

the intraembryonic coelom is

Back 37

the cavity between somatic and splanchinic mesoderm . will be subdivided into pleural , pericardial , and peritoneal cavities

Front 38

how and when does body folding work

Back 38

beings late in the third week , cephalo-caudla (cranial-caudal) and later , results in tubualr embryo (tube within a tube ) . yold stalk is progressivly reduced in size , essentially complete by six week

Front 39

tubualr embyro forms

Back 39

1. alimentary tract ( gut tube)

2. body cavity

3. body wall

Front 40

derivatives of germ layers for the ectoderm

Back 40

- central nervous system

-peripheral ns and adrenal medulla ( nerual crest)

-sensory epithelia of ear, nose and eye

- epidermis ( including hair and nails)

- mammary gland, pituitary gladn, and subcutaneous glands

-enamel of teeth

- dentin and pulp of teeth , pdl (nerual crest)

Front 41

drivatives of germ layer of the mesoderm

Back 41

- CT(including cartilage and bone)

- all muscle , both striated and smooth

- heart , blood and lymph vessels , and blood and lymph cells

- kidney , gonads, and thier ducts

- serous membranes lining the pericardial , pleural , and peritoneal cavities

- spleen, tonsils, lymph nodes and cortex of adrenal gland

Front 42

derivatives of germ layer of the endoderm

Back 42

- eipthelial lining of gastrointestinal and respitory tracts

- parenchyma of thyroid, parathyroid, thymus, liver , and pancreas

-epithelial linig of tympanic cavity and auditory tube

-epithelial lining of unrinary bladder and urethrea