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64 Cards in this Set

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  • Back
What are 3 trimesters of fetal development?
Germinal stage, embryonic stage, and fetal stage
When is an ovum considered an ovum?
Fertilization to hatching
When is an embryo considered an embryo?
From hatching to implantation
When is a fetus considered a fetus?
From implantation to parturition
Describe the germinal stage
2 cell --> 4 cell --> 8 cell --> morula --> blastocyst
What is a morula?
A round mass of blastomeres
Describe the embryonic stage
Blastocyst hatches and leaves zona pellucida. It is then free-floating within the uterus. Embryo undergoes massive growth.
What causes the blastocyst to hatch?
Growth & fluid inside, production of enzymes of trophoblast, and contraction of the blastocyst
What are the extraembryonic membranes formed during the embryonic stage?
Amnion, yolk sac, chorion, and allantois
Which membrane is a fluid-filled protective sac for developing fetus?
Amnion
Which membrane contributes to the formation of the umbilical cord?
Yolk sac
Which membrane is the source for placental attachment?
Chorion
Which membrane is a fluid-filled sac that collects liquid waste from embryo?
Allantois
What do the allantois and chorion merge to form?
Allantochorion, which is the fetal contribution to placenta
What becomes the embryo proper?
Inner cell mass
What are the 2 major cell types in the trophoblast?
Syncytiotrophoblast cells and cytotrophoblast cells
What does the hatched blastocyst look like in the cow, ewe, and sow?
Thread-like free floating embryo
What does the hatched blastocyst look like in the mare?
Spherical free floating embryo
Where is the inner cell mass found?
In the blastocoele
What gives rise to the yolk sac?
An evagination in the ventral portion of the embryo proper gives rise to the yolk sac
How is the chorion formed?
By fusion of the trophoblast and the primitive endoderm
Where does the allantois develop from?
From the primitive gut
What regresses as the allantois begins to expand?
Yolk sac
What results from the fusion of the chorion edges?
Amnion and amniotic cavity
What are the 4 types of placenta?
Diffuse, zonary, discoid, and cotyledonary
What characterizes the diffuse placenta?
Covered by chorionic villi
What species have diffuse placenta?
Horse, pig, and donkeys
What characterizes cotyledonary placenta?
Placentome, cotyledons, and caruncles
What species have cotyledonary placenta?
Cow, ewe, and goat
What characterizes the zonary placenta?
Central aggregation of chorionic villi near conceptus
Which species have zonary placentas?
Dog and cat
What characterizes discoid placenta?
Discs of chorionic villi
Which species have discoid placenta?
Rodents and primates
Describe epitheliochorial placenta
Maternal and fetal epithelium are intact, large surface area.
Which species have epitheliochorial placentas?
Mares and sows
Describe the syndesmochorial placenta
Maternal epithelium eroded; binucleated giant cells.
Which species has syndesmochorial placenta?
Ruminants
Describe the endotheliochorial placenta
Endometrial epithelium absent. Maternal capillaries exposed.
Which species have endotheliochorial placenta?
Dogs and cats
Describe hemochorial placenta
Fetal epithelium surrounded by maternal blood, very intimate.
Which species has hemochorial placenta?
Primates
Describe hemoendothelial placenta
Fetal capillaries surrounded by maternal blood (no direct exchange), most intimate
Which species have hemoendothelial placentas?
Rabbits and rodents
What kind of placenta does a cow have?
Cotyledonary
How many cotyledons does a cow placenta have?
70-120
What structure do the cotyledons on a cow placenta have?
Convex
How many layers of tissue separate the fetal and maternal blood?
5
Are cotyledons on the fetal or maternal side?
Fetal
Where do cotyledons originate from?
Trophoblasts
What are cotyledons made up of?
Blood vessels and CT
Where are caruncles located?
On the endometrium on the maternal side
Characteristic of caruncles?
Highly vascular
What type of placenta do sows have?
Diffuse
Describe the diffuse placenta
Uniform distribution of chorionic villi that cover the entire surface of the chorion (regions of nutrient transport)
How many layers separate fetal and maternal blood?
6
What kind of metabolic exchanges occur through placenta?
Nutrient and gas exchange
How does the placenta serve as a transient endocrine organ?
Maintains pregnancy, stimulates ovarian function, influences fetal growth, and assists in parturition
What are the 3 types of exchange that occur through the placenta?
Simple diffusion, facilitated diffusion, and active transport
What is simple diffusion in the placenta?
Gases and water flow from high concentration to low concentration
What is facilitated diffusion in the placenta?
Using complex molecules such as glucose and AA to exchange nutrients
What is active transport in placenta?
Sodium/potassium pump and calcium pump
What are some substances that can cross the placental barrier?
Small hormones, water-soluble minerals and vitamins, antibiotics, opiate drugs, barbiturates, lead, viruses, LSD, amphetamines, lithium
What substances can't cross the placental barrier?
Maternal proteins, lipids, large peptide hormones, fat-soluble vitamins
How does the placenta function as maternal recognition of pregnancy?
Prevents luteolysis, prevents decrease in blood progesterone, and to maintain pregnancy