SGU Embryology Part I -General Embryo
pages 1-32 of Part I General Embryo Gupta's class Fall 2011
Somatopleure consists of
Somatic Mesoderm + Ectoderm
Splanchnopleure consists of
Splanchnic Mesoderm + Endoderm
Paraxial Mesoderm later forms
Nucleus Propulsus develops from
Annulus Fibrosus develops from
Mesenchyme of Sclerotome
Extraembryonic Somatopleure consitutes the
Amnion and chorion
Extraembryonic Splanchnopleure constitutes the
Yolk Sac and Allantois
Yolk Sac has what type of vessles
Allantois has what type of vessels
Superficial Implantation is
The embryonic sac lies in the lumen
Superficial implantation occurs in which animals?
Ruminants Equine Porcine
Eccentric Implantation is
the embryonic sac lies in a fold or pocket
Eccentric implantation occurs in what animals?
Rat and Squirrel
Interstitial Implantation is
The embryonic sac penetrates and is embedded in the uterine wall
Interstitial Implantation occurs is which animals?
Guinea Pig Carnivores and Man
Histotrophic Nutrition is
Nutrition from secretion of Uterine Gland
Hemotrophic Nutrition is
Nutrition from Maternal Circulation
Choriovitelline Placetation is
Yolk Sac combines with the Chorion to form placenta --Horse and dog 1st 1/4 gestation
Allantois combines with Chorion to from placenta ruminant pig carnivore equine
Diffuse placenta is found in what animal?
Mare and Sow
Cotyledonary placenta is found in what animal?
Zonary plaenta is found in what animals?
Discoidal placenta isfound in which animal?
Primates Rodents and Bats
Villous Branching is
Simple branching of chorionic villi--sow mare and ruminants
Labyrinthine Branching is
Complicated branching of chorionic villi --carnivores and primates
Deciduate loss is
Extensive loss of maternal tissues at time of parturtiton carnivores and primates -- always paired with Labyrinthine
Non-Decdiuate loss is
Little loss of maternal tissue at time of parturition sow mare and ruminants -- always paired with
What is the route of Maternal to Fetal circulation?
Uterine A >Umbilical V >Umbilical A >
All 6 layers present
Chorionic epi >Uterine epi
Sow and Mare
5 layers present
Chorionic epi > Uterine CT
4 Layers present
Chorionic epi >Endothelium of Uterine vessels Carnivores
3 layers present
Chorionic epi > Uterine blood
Classify the Sow and Mare's Placenta
Diffuse Villous Non-Deciduate, Epitheliochorial
Classify the Ruminant's placenta
Cotyledonary, Villous, Non-Deciduate, Syndesomchorial
Classify the Dog / Cat placenta
Zonary, Labyrinthine, Deciduate, Endotheliochorial
Classify the Primate's placenta
Discoidal, Labyrinthine, Deciduate, Hemochorial
Define Pre-embryonic period
Up to implantation
Define Embryonic period
Implantation to origin of organs and formtion of basic body form
Define Fetal period
Growth and maturation of the organ system
What animals are induced ovulators?
Cat and rabbit
What is polytocus?
More than one oocyte is released -- Dog cat sow ruminants
What is monotocus?
Only one oocyte is released
How long are ova/ sperm viable?
Sperm -Usually 1-2 days, up to 6-7 days in horse and dog, 32 days in fowl, 70 in turkey. Ova are usually viable for 24 hours.
What is the site of fertilization?
Infundibulum in dogs, Ampulla in other species
What is capacitation?
Removal of glycoprotein coat
What is the acrosomal reaction?
Release of enzymes to facilitate penetration of the oocyte
What is the zona reaction?
Chemical changes in the zona pellucida that pervent polyspermy
Describe Monozygous Twinning
One oocyte is released, divides att he blastocyst stage into two gentically identical masses. Always same sex, identical twins.
Describe Dizygous Twinning
Two seperate ova are fertilized, fraternal twins
What is a freemartin?
In Dizygous twinning a common circulation of the embryos, the female is born infertile b/c of the influence of testosterone produced by male embryo.
What is Polyspermy?
More than one sperm penetrates the female germ cell - common in pig and birds
What is Superfecundation?
2 different daddies --cats and dogs
What is Superfetation?
Second younger fetus -- pigs
It can still be termed a Morula if the ___________ is intact
What is the trophoblast used for?
The embryonic disc differentiates in to 3 germ layers
What are the 3 Germ Layers?
Ectoderm Mesoderm Endoderm
What is Delamination?
Detachment of the cells from the inner cell mass
What is the Gestation of the Mare?
335-345 days ~ 11 mo
What is the Gestation of the Cow?
279-282 days ~ 9 mo
What is the Gestation of the Ewe?
148-150 days ~ 5 mo
What is the Gestation of the Sow?
114-120 days remember 3 mo 3 weeks 3 days
What is the Gestation of the Dog and Cat?
Dog 60-65 days
Cat 60 days
What is holoblastic cleavage?
Complete division of the zygote- mammals
What is meroblastic cleaagve?
Partial division of the zygote, yolk prevents complete division -- birds
How is embryonic age measured?
Early - # of somites, later Crown rump length
When is implantation for the Sow and Cat?
When is implantation for Dog?
When is implantation for Ewe?
When is implantation for Cow?
When is implantation for the Mare?