Term
|
Definition
| The event where the embryo becomes fixed in position and physical contact with the endometrium is established |
|
|
Term
Timing of implantation
(Rodent & Primate) |
|
Definition
| Blastocysts implant into the uterus within a day of shedding the zona pellucida |
|
|
Term
Timing of Implantation
(Livestock, dog & cat) |
|
Definition
Will have several days to weeks between zona pellucida loss and uterine attachment
(period of substantial embryonic growth and development) |
|
|
Term
Pre-implantation events
(polytoccus species) |
|
Definition
Embryo spacing
Transuterine migration |
|
|
Term
|
Definition
blastocysts will space equidistantly throughout the uterine horns
(rabbits, rodents, swine, dogs) |
|
|
Term
|
Definition
| Blastocysts will move from the uterine horn of higher blastocyst density to the less dense uterine horn to effect equal (or near equal) distribution of blastocysts between horns |
|
|
Term
Pre-implantation events
(monotoccus species) |
|
Definition
| can also undergo transuterine migration in the case of twins |
|
|
Term
| Delayed Implantation not to be confused with.... |
|
Definition
| the gap between hatching and attachment in the livestock sp and dogs and cats is not to be confused with the species characterized as undergoing delayed implantation (armadillo, badger, bear, mink, sea lion, seals, skunks, shrews, marsupials) |
|
|
Term
| Delayed Implantation differs in two key features |
|
Definition
- Blastocyst in delayed implanting sp enters diapause
- low metabloic rate
- low RNA and protein synthesis
- no growth
- remains free-floating in uterus
2. possible to modify the interval of delay, and hence, gestational length, by environmental or physiologic means |
|
|
Term
|
Definition
| state of suspended growth or dormancy |
|
|
Term
| Naturally delayed implantation |
|
Definition
trigger for implantation is linked to an environmental change such as photoperiod
Example: badger- 11 month gestation. Subjected to artificial photoperiod gestation can be decreased to 6 months (hence the badger blastocyst spends 5 months in diapause) |
|
|
Term
| Physiologically delayed implantation |
|
Definition
trigger for implantation is linked to physiologic event such as suckling
Example: marsupials- fertilization and embryo development occurs during lactation and suckling but the blastocyst enters diapause until the offspring stops suckling. Kangroo- delayed implatning blastocyst, fetus in pouch, joey at side |
|
|
Term
| Tigger mechanism for implantation |
|
Definition
- linked to a biological clock set at fertilization
- time-dependent expression for specific genes involved in implantation
|
|
|
Term
Trigger mechanism for implantation
(livestock species) |
|
Definition
| timely expression and exposure of complementary cell adhesion molecules between the trophectoderm(outer layer of chorion) and the endometrial epithelium to allow attachment |
|
|
Term
| Implantation in invasive species |
|
Definition
| timely expression of trophectodermal proteases (collagenase-type) that erode the endometrium to facilitate blastocyst invasion |
|
|
Term
| Blastocyst estradiol role in implantation |
|
Definition
- has a hyperemic effect on target tissues where it can induce an increased blood flow to that tissue
- proposed to generate a localized inflammation over the blastocyst implantation site in the endometrium
- prepares the uterus for implantation
|
|
|
Term
| Livestock sp produce similar repertoire of proteases at similar developmental stages (after loss of ZP) yet neither make immediate contact with nor invade the endometrium. Why? |
|
Definition
- livestock sp, both the blastocyst and endometrium produce several types of protease inhibitors that are believed to neutralize the blastocyst proteases
- in livestock sp, the protease inhibitors are also abundant in the uterine lumen
- in invasive sp, the protease inhibitors are not as abundant in the uterine lumen and tend to be restricted to the endometrium
|
|
|
Term
|
Definition
- Coincident with implantation is development of the placenta
- fusion or apposition of the fetal membranes to the endometrium to permit physiologic exchange between the fetus and the dam
- the placenta is a composite organ made up of fetal membranes and endometrium and functions in nutrition, respiration and excretion for the fetus
|
|
|
Term
| Placental Classifications |
|
Definition
- Distribution of chorionic villi
- placental barrier
- Deciduate vs. non-deciduate
|
|
|
Term
Distribution of chorionic villi
(placental classifications) |
|
Definition
| superficial classification |
|
|
Term
Placental Barrier
(placental classifications) |
|
Definition
number of tissue layers seperating maternal and fetal circulation (6 layers if no endometrial penetration)
Provides information regarding degree of invasiveness |
|
|
Term
Deciduate vs. non-deciduate
(placental classifications) |
|
Definition
| refers to the amount of maternal tissue lost at parturition and the development of decidua |
|
|
Term
| Distribution of Chorionic Villi |
|
Definition
- diffuse
- cotyledonary
- zonary
- discoid
|
|
|
Term
Diffuse
(distribution of chorionic villi) |
|
Definition
Swine, horses, camelids
DIFFERENCE IN HORSES
- day 75-110 of gestation, microcoytledons appear= denser patches of chorionic villi
|
|
|
Term
Coytledonary
(distribution of chorionic villi) |
|
Definition
|
|
Term
Zonary
(distribution of chorionic villi) |
|
Definition
|
|
Term
Discoid
(distribution of chorionic villi) |
|
Definition
| Rodents, rabbits, primates |
|
|
Term
|
Definition
| In the completly non-invasive type of placenta, there are 6 tissue layers comprising the placental barrier |
|
|
Term
| Endometrial layers of placental barrier |
|
Definition
- endometrial endothelium= capillary wall (1)
- endometrial interstitium or connestive tissue(2)
- endometrial epitheliem (3)
|
|
|
Term
| Fetal membrane layers of placental barrier |
|
Definition
- chorion (4)
- fetal interstitium or connective tissue (5)
- fetal endothelium= capillary wall(6)
|
|
|
Term
| 5 Types of Placental Barriers |
|
Definition
- Epitheliochorial (6)
- Synepitheliochorial (6, but modified)
- Endotheliochorial (4)
- Hemochorial (3)
- Hemoendothelial (1)
|
|
|
Term
|
Definition
| possess decidua and lose endometrial tissue at parturition |
|
|
Term
|
Definition
| raised vascular protrusions comprised of enlarged endometrial (decidua) cells located at the site of implantation |
|
|
Term
|
Definition
- Endotheliochorial
- Hemochorial
- Hemoendothelial
- Greater loss of tissue with hemochorial species compared to moderate loss associated with endotheliochorial species
|
|
|
