EMBRYOLOGY (Lecture 9) Flashcards by Riley Hrasky

what makes up a corona radiata

zona pellucida + layers of follicular cells

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Follicular cells

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secondary oocyte

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zona pellucida (glycoprotein coat)

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oocyte

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follicular cells

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zona pellucida

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fertilized oocyte becomes a ______

zygote

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genetic sex determination takes place when?

the diploid zygote is formed

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term for a new embryonic cell

blastomere

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term for a superficial layer around a central core of cells

Morula

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what forms the blastocystic cavity

secretions from the blastomeres

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the initial series of mitotic divisions by which the larger zygote is fractionated into numerous ‘normal sized’ cells

cleavage

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each daughter cell of the cleavage process is called a ____?

blastomere

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cleavage begins w/ a _____, progresses through compaction to the _______ stage and terminates w/ the start of the ______ stage

cleavage begins w/ a ZYGOTE, progresses through compaction to a MORULA stage and terminates at the start of the BLASTOCYST (blastula) stage

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The first 8 blastomeres are _______ and have identical potential in mammals

undifferentiated

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once a cavity appears, a morula is called a _______?

blastocyst

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the male pronucleus forms from the ______

enlarged sperm nucleus

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with each division in mitosis, the blastomeres get _______ in size

smaller

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what does totipotent mean

an immature cell that can give rise to any cell type

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the trophoblast forms the _______ layers of the placenta

embryonic

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blastocyst emerges from the ________

zona pellucida

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cattle and horses undergo what type of conceptus

single conceptus

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dogs and cats undergo what type of conceptus

polytocous

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All three germ layers (ectoderm, mesoderm, endoderm) originate within the _______

epiblast

what is Neurulation

The transformation of the neural plate into the neural tube

what induces neurulation

the notochord

what is gastrulation

when the 3 primary germ layers become distinct (ectoderm, mesoderm, endoderm) *begins w/ the primitive streak

what are the two parts of the placenta and where do they derive from?

- a fetal part (develops from the chorionic sac) - maternal part (Derived from the endometrium)

what is the endometrium?

the lining of the uterus

the fetal part of the placenta and the fetal membranes separate the fetus from the _______

endometrium

after body folding occurs, trophoblasts get a new name, _______

chorionic

main function of the placenta

communication b/w mother and fetus

what happens in implantation

fetus attaches to uterus lumen

what is the mesometrium?

ligament that hangs the uterus in place

the chorioallantoic membrane is where the ____ + _____ touch

chorion + allantoic

blood vessels of the placenta develop from the _______

extraembryonic mesoderm (and they grow up through the yolk sac)

somites originate from what

lateral mesoderm

when does the blastocystic cavity become the exocelemic cavity

with the presence of hypoblasts

when does the exocelemic cavity become the primitive yolk sac

once the exocelemic cavity becomes entirely enclosed by hypoblast

what does the prechordal plate ultimately become

the mouth

the notochord induces ______ which is immediately followed by _______

neurulation, followed by body folding

what does the ectoderm go on to make

the epidermis, the CNS, the neural crest

the endoderm replaces what cells

hypoblast

the endoderm goes on to make what

makes the gut lining

parvovirus is a disease of the what

endoderm

when the caudal neural cord fails to close properly, what happens

spina bifida

horses have what placenta type and describe it

Epitheliochorial type epithelio = mother layer chorial = baby layer the endometrial epithelium (mothers layer) remains intact and is near to the chorionic epithelium (baby layer) * have diffuse placenta meaning it wraps entirely around

what are chorionic girdle and endometrial cup? when do you see them?

the chorionic girdle and endometrial cups are areas of greater maternal/fetal attachment CHORIONIC GIRDLE ( ~ day 35) - present when the choriovitelline membrane is still present - present when definitive yolk sac larger ENDOMETRIAL CUPS (~ day 70) - think: older so more developed and can use sippy CUP - present once the choriovitelline membrane is gone - size of definitive yolk sac is reduced

what type of placentation do horses have

diffuse meaning the placenta is all over

what are equine microcotyledons

areas where the fetal and maternal microvillous (microvilli) interdigitate

what does precocial infants mean and what species have them

precocial = born with eyes open, full hair coat, mobile ex: horses

what does altricial infants mean

altricial infants require a lot more care ex: puppies, kittens, human babies

what is the placenta type in cattle

synepitheliochoridal - same as horse but 'syn' implied the added binucleate cells - syn 'sin' Bi - BINUCLEATE CELLS (fetal origin) - areas of combined maternal and fetal epithelium called CRYPTAL epithelium

placentation in cattle....name for it and explain

cattle: cotyledonary placentation **carnucles on maternal side, mom drives the car **cotyledon on fetal side, you coddle a baby PLACENTOME = carnucle + cotyledon

(Cattle) what comprises the placentome

caruncle + cotyledon

what is the placenta type in dogs and cats

Endotheliochordial type - chorion comes into direct contact w/ maternal (endometrial) capillaries - maternal uterine endothelium and CT is gone

what is the placentation type in dogs and cats

ZONARY placentation - zonary meaning not all sides of the fetal placenta are attached to the mother -

monozyogtic vs dizygotic twins

monozygotic is when two fetuses share one ovum Dizygotic is when each fetus has their own ovum (2 ova)

MZ twinning usually begins in the _______ stage

blastocyst 65% of MZ twins develop after the separation of the blastocystic cavity - 1 placenta, 1 chorionic scac, 2 amniotic sacs

when separation of the embryonic disc occurs before the formation of the blastocystic cavity, MZ twins have ____ amnion, ___ chorions, and ____ placentas

2 amnions, 2 chorions, 2 placentas

what problems can occur when MZ twins originate from the division of the embryonic disc late in week 2

when division of the embryonic disc occurs late in week 2, the embryos share a single placenta and single amniotic sac - conjoined twins or parasitic twin

what cells form the prechordal plate

hypoblasts

during gastrulation, all 3 germ layers form from the _____

epiblast

what do the blood vessels develop from

extraembryonic mesoderm