embryo, review, slides

8/3/2019 Embryo, Review, Slides

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Gametogenesis

Testis

structure - seminiferous tubules

lining epitheliumgerminal epithelium

- Sertoli cells

- basal lamina

parenchymaspermatogenic cells

specific subtypepseudostratified

columnar epithelium

subtypesimple, single layer

fundamental type - epithelialstromaspecific subtype

loose connective tissuebetween

seminiferous tubules

- subtypeconnective tissue proper,

fibrous/collageneous, regular- parenchymafibroblast

- interstitial cell of Leydig

secrete testosterone


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Cells of the lining epithelium - under the influence oftestosterone

spermatogonia 2n, diploid

Type Apale staining nucleus

mitotically activepuberty

Type Bdark nulcei

mitotically inactive

precursor of type A

primary spermatocyte 4n, tetraploid

secondary spermatocytes 2n, haploid

spermatids 1n, haploidspermatozoa 1n, haploid

Sertoli cellssythesize ABP2n diploid

secrete inhibininhibit FSH synthesis and

release

secrete fluidtransport of sperm cellsunder the influence of FSHanterior pituitary

promote the synthesis of ABP


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Ductus epididymisextratesticular genital duct

lining epitheliumspecific subtype - pseudostratified

columnar epithelium with stereocilia

long modified microvilli

- basal lamina

- subtypesimple, single layer

- fundamental typeepithelial tissue

- specialized membrane structure

stereocilia

- under the influence of testosterone

principal cellstall columnar with stereocilia- reabsorb and phagocytize residual

bodies not removed by sertoli

- secretoryglycerophocphocholine

androgen

basal cellsstem cellsmuscle coatinner circular and outer longitudinal smooth

muscles

- peristalsis

- specific subtypesmooth muscle

- subtypemuscle- fundamentalmuscle tissue


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Ovary

coveringmesothelium of peritoneum

compartment/layer

cortexprimary oocyte-containing ovarian follicle

stromafibrous connective tissue

medullablood vessels

loose connective tissue

no ovarian follicle

Ovarian follicleprimary oocytearrested in prophase,

first meiotic division

- surrounding epitheliumfollicular cellswith basal lamina

primordial folliclesimple squamous

primary follicle

unilaminar - simple cuboidal

multilaminar -stratified cuboidal - granulosa cellszona pellucida - glycoprotein

stromatheca internacellular layer

theca externafibrous layer

not dependent to FSH


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secondary follicle - fluid-filled spacecoalase - antrum

dependent to FSHstimulategranulosa

cells to convert androgen to estrogen and

manufacture LH receptors

- theca internasythesize androgen

tertiary folliclemature graffian folliclegranulosacumulus oophorus

corona radiata

LH surge

completion of first meiosis just prior to ovulation

ovulation occurs

release of secondary oocytes from mature graffian follicle

trasnform into secondary oocytesarrested at

first polar body metaphase second meiosis

- free in the peritoneal cavity

- cumulus oophorus

- corona radiata- zona pellucida

remaining granulosa cells and thecacorpus luteum of pregnancy


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C l t


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Corpus luteum

granulosa lutein cellsperipherally located

synthesize most of progesterone

theca lutein cellscentrally located

synthesize progesterone

progesterone

prepares and maintain endometrium

for implantation

primary oocyte - 4n, tetraploid

- arrested at prophase, diplotene stagefirst meiotic division

- complete prior to ovulation, before it is

release from the mature graffian follicle

secondary oocyte - 2n, haploid (two chromatis)

- arrested at metaphase, secondmeiotic division

- first polar body

- completed during fertilization

occurs in the fallopian tube - ampulla


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stim l s for the completion of second meoisis


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stimulus for the completion of second meoisis

1. sperm penetrate corona radiata and zona pellucida

2. plasma membrane of sperm and oocyte fuse

products of second meiotic division

Ovum - 1n, haploid ( one chromatid)second polar body

Fallopian tube

mucosa

lining epitheliumspecific subtype - simple columnar ciliated

( transport ) and secretory/peg cell

( nutrient-rich medium)

subtypesimple, single layer

fundamental - epitheliallamina propialoose connective tissue

muscularis - inner and outer layers of smooth muscle

rhythmic contraction

serosamesothliumsimple squamopus epithelium


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Uterus


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Uterus

layer - endometrium

sublayerfunctional layer

under the influence of estrogen and

progesterone

spiral arteriesbasal layer

cyclic regeneration

mucosa

lining epitheliumspecific subtype

simple columnar ciliated- basal lamina, type IV collagen

endometrial glandssimple columnar

endomatrial stromastromal cells

Functional layer

estrogen effectsproliferative phaseglands and mucosa proliferate

progesterone effectspredecidua

secretory glands - glycogen


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Blastocyts


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Blastocyts

formed in the fallopian tubeampulla

from morula

with zona pellucidadissolution allowsimplantation to

occur

cellsblastomere - 2n, diploidblastocoelecavity - become yolk sac

inner cell mass ---- embryo - fetus

epiblast

hypoblast

amnionouter cell masstrophoblast - placenta

cytotrophoblastaround the

blastocoele and inner cell mass

divide and fuse to formsyncytitrophoblastouter , around the remaining

cytotorphoblast

Placenta - hemchorial placenta maternal blood directly


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Placenta - hemchorial placentamaternal blood directly

bathes the chorionic surface

1. membrane

amnionamniotic cavity

- anlageepiblast (floor of amniotic cavity)

- simple cuboidal epitheliumchorionanlage - extraembryonic mesoderm

fused with amnion

2. chorionic plate

anlageextraembryonic mesoderm

anchoring chorionic villi - give rise to branch villiproject into the intervillous space

free or floating chorionic villi

fetal surface


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3rd trimester placenta/mature placenta/ term placenta


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3 t este p ace ta/ atu e p ace ta/ te p ace ta

tertiary villi - interconnect umbilical arteries and vein

surface epithelium - syncytiotrophoblast

fused cytotrophoblast mutinulceated

arrangement - syncytium

secreteHCG, progesterone andlactogen

stroma - loose connective tissuemesenchymal

extraembryonic mesoderm

capillariesderived from fetal blood vessels

fetal blood

4. intervillous spacesanlagelacunae

contentsmaternal blood and floating villi


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3. umbilical cord


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anlageconnecting stalk

Whartons jellyloose connective tissue

- rich in Hyaluronic acid

- rubbery, gelatinous characterunlikely that

twist or turns will result in constrictions ofthe vessels

umbilical arteriesinternal iliac artery, superior

vesical aretries and medial

umbilical ligaments

- deoxygenated blood from fetus

umbilical veinligamentum teres- oxygenated blood from the placenta to the

fetus

- drain the placenta

allantoisdiverticulum of yolk sac

fateurachus - band of fibrotic connective tissue

attaches the bladder to the umbilicus


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5. Decidua


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maternal surface

feeding vesselmaternal spiral arteries

aprenchymadecidual cells

endometrial stromatransformed by progesterone

anlagepredeciduaFunctions

limit the invasiveness of syncytiotrophoblast

preventing materna immunologic recognition

secrete nutrients


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Development of Musculoskeletal System


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intraembronic mesoderm

somites

sclerotome

vertebral column

ribssternum

skull

associated connective tissue

dermatomyotome

dermis and skeletal muscleintermediate mesoderm

lateral mesoderm

somatic mesoderm

body musculature

limbsplanchnic mesoderm

visceral organs - smooth muscle, connective

tissues

notochordnucleus pulposus


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Development of skin


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surface ectoderm

epidermis

hair budanlage of hair follicle

sebaceous glandsanlage hair bud

secretion sebumepithelial cord of cellsanlage of sweat glands

dermatome

papillary layerloose connective tissue

reticular layerdense irregular connective tissue


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Development of the Respiratory System


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Nasal cavities

nasal placode ( ectodermal thickening ) - anlage

invaginate into the

nasal swellingmesenchyme

formingNasal pit

Respiratory diverticulum - anlage of trachea bronchus,bronchioles and lungs

- derived from foregut

- tracheo-esophageal septum

completely separate it from

developing esophagus

endoderm - lining epithelium and serous mucous

glands, pneumocytes I and II

splanchnic mesoderm - connective tissue, smooth

muscle, cartilage, BVs and lymphatics

alveoli

Pericardioperitoneal canalsanlage of pleural cavities


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Glandular stagerespiratory diverticulum to 4th month of

development


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Development of the Cardiovascular Systemmesechyme (surrounding the blood islands)


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mesechyme (surrounding the blood islands)

differentiate into endothelial cells

vesicular sacs

fuse --------- primitive blood vessels

endocardial heart tubeanlage of heart- endothelial cellsdifferentiate

into endocardium

myoepicardial mantleanlage of myocardium and

epicardium

- splanchnic mesodermbetween heart tube and mantlecardiac jelly

endocardial cushion

Heart

conduct blood to the aortic arches

drain into the dorsal aorta

descending aorta


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Primitive heartthree major vessels empty into sinus venosusvitelline vein


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vitelline vein

umbilical vein

common cardinal vein

drain the head and neck - superior vena cava

bodysubcardinal veinanalageposterior cardinal vein

later form

left renal

gonadal

supra renalinferior vena cava bet renal vein and the

liver

vitelline veinsanlage of

liver sinusoidsanlage - left vitteline vein

hepatic vein

portal veinanlage - left vitteline vein

posthepatic IVCanlage - right vitelline vein

Umbilical veinanlage of hepatic sinusoids


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anlage of hepatic sinusoids

Ductus venosuscoalescence of hepatic sinusoids

- anlage - vitelline vein and umbilical vein

- receive oxygenated blood from the umbilicalvein

Fate of

umbilical veinligamentum teres hepatisstreak of

connective tissueductus venosusligamentum venosumband of

connective tissue

umbilical arteriesmedial umbilical ligaments

branches of umbilical arteriespersistblood supply to

Urinary bladder

DEVELOPMENT OF THE VENOUS SYSTEM


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O O OUS S S

develops from the vitelline, umbilical, and cardinal veins that empty into the

sinus venosus.


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Development of the Digestive Systemprimitive gut anlage part of yolk sac


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primitive gut anlage part of yolk sac

foregutceliac artery

midgut - superior mesenteric artery

hindgut - inferior mesenteric artery

yolk sac endodermlining epithelium and the glands

splanchnic mesoderm

lamina propia - loose connective tissue

submucosadense irregular

muscularis - smooth msucleserosamesothelium

neural crest

Myenteric plexus and Meissners plexus

Foregut diverticula anlage of

liver diverticulumliver

biliary apparatus

hepatic duct, CBD, GB

dorsal and ventral pancreatic buds - pancreas


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Esophagusskeletal muscle in the muscularis externa derived from


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skeletal muscle in the muscularis externa derived from

pharyngeal arch mesenchyme

smooth muscle in the muscularis externasplanchnic

mesodermStomach

fusifrom dilatation of foregutanlage

suspended by dorsal and ventral mesogastrium

Proximal duodenum

anlagecaudal portion of foregut and cranial portion of

midgutjunction of foregut and midgut

entrance of CBD into the duodenum

Liver and Biliary apparatus

liver diverticulumanlage

hepatic cords

intrabiliary ducts

epithelial ling of the bilary apparatus - hepatic duct and

GB

splanchnic mesodremglissons capsule, reticular stroma

smooth muscle of the biliary apparatus


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Pancreasanlagedorsal and ventral pancreatic buds


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g p

ventral pancreatic bud

main pancreatic duct

uncinate process

head, inferior portiondorsal pancreatic bud

accessory pancreatic duct

rest of the pancreasbody and tail

endodermally derived

cells of islet of Langerhanalpha and beta cellspancreatic acinar cells

lining epithelium of the intra and extra pancreatic

ducts

Midgut

herniation - segments project into the extraembryonic

coelom surrounded by components of umbilical cord

intestinal loopssegments distal to bile duct to

proximal two third of the transverse colon


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Hindgutdistal one third to proctodeum


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p

cloacaexpansion at most caudal extent

anlage of rectum and anus

lining epitheliumendoderm

connective tissue and musclessplanchnic mesoderm

divide by urorectal septum into

rectum

anal canal

urogenital sinus


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embryo, review, slides

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