Chapter 7,8,9 Flashcards
How long does it take for a developing mammalian embryo to reach the uterus?
3 days
What supplies the nutrition of embryo prior to its implantation to endometrium?
Own yolk, and reproductive tract secretions
Serves as the protection for the developing embryo against maternal immune system
Zona pellucida
Serves to nourish the developing embryo after it hatches from zona pellucida before it attaches to epithelium of uterus.
Secretions of uterine glands
The process wherein the developing embryo attaches or adheres to the epithelium of the uterus
Implantation/nidation
Apposition, Adhesion and Firm attachment
3 stages of implantation
Blastocyst implants itself interstitially by passing through the uterine epithelium and becoming completely cut off from the uterine lumen. This is true in primates, guinea pigs and human.
Interstitial/Invasive Implantation
blastocyst remains small and becomes lodged in the fold of the uterine lumen, where it implants itself. Example of this form of implantation are
rodents.
Eccentric Implantation
Blastocyst elongates and enlarges until it fills a good part of the uterine cavity. This form of placentation occurs in ungulates, carnivores, swine,sheep, cattle and horse
Centric/Superficial Implantation
Blastocyst implants in the endometrium on the same side as the attachment of the mesometrium.
Mesometrial Implantation
implantation occurs at a site opposite to the attachment of the mesometrium
Anti-mesometrial Implantation
Implantation occurs when the probability that
offsprings are born at a time of year favorable for survival. E.g. for Mink, ferrets, roe deer, bears, badgers and seals
Seasonal or Obligative Implantation
The dam ensures that it does not have to support two litters contemporaneously
* Rodents and insectivores
Facultative or lactational Implantation
Implantation and subsequent embryonic development in an extra-uterine location
Ectopic pregnancy
These are the sites of ABNORMAL implantation
Ovary, uterine tube, peritoneal cavity
This is a natural placement or orientation and spacing of the embryos that occur in the uterus of the dam.
Embryo orientation and spacing in – utero
True or false in cattle When single oocyte is fertilized, the blastocyst attaches to the middle or upper third of the uterine horn adjacent to the ovulating ovary.
TRUE
True or false in sheep When two blastocysts are derived from one ovary, one blastocyst usually migrates to the contralateral
(opposite) horn where it becomes implanted.
TRUE
True or false in Horses blastocyst will only implant at the left horn close to the body of the uterus.
False, blastocyst will implant on either left or right side of the horn.
True or false for litter bearing or Polytocous animals blastocyst are evenly spaced within the uterine horns.
TRUE
These are tissues derived from the developing embryo that enclose and contribute
to the support of the developing embryo.
Extra embryonic membranes
What are the 4 EEM’s?
Yolk sac, allantois, amnion and chorion
Where are the amnion and chorion derived from?
Somatopleure (fused mesoderm and ectoderm)
Where are the allantois and yolk sac derived from?
Splanchnopleure (fused mesoderm and endoderm)
Is a small membranous structure in egg with scant yolk material like mammals, performs a variety of critical biological functions during early gestation.
Yolk sac
Provides the nutrition and gas exchange between the mother and developing embryo
Yolk sac
Takes place in yolk sac before the liver and bone marrow eventually take over. It is the provision of oxygen to organs.
Primitive hematopoiesis
Remnant of yolk sac after birth
Meckel’s diverticulum
Blood supply is provided by which vessel during the 6th day of incubation?
Vitelline vessels
the outermost membrane surrounding the embryo in mammals, birds and reptiles, also involved in gas and nutrient exchange due to its vascularity
CHORION
Serves as the cushion to protect the embryo
Chorionic fluid
the fetal part of placenta
chorion
the maternal component of placenta
decidua basalis
Membranous sac that intimately encloses the embryo when first formed. It is which serves to provide a protective environment for the developing embryo or fetus.
AMNION
In the early weeks of pregnancy is mostly
water that comes from the body. After about 20 weeks of pregnancy, the baby’s urine makes up most of the fluid.
Amniotic fluid
A hollow sac-like structure filled with clear fluid that forms part of a developing amniote’s conceptus. Helps the embryo exchange gases and handle liquid waste
ALLANTOIS
Are the continuation of the sinus venosus of the heart.
Allantoic veins
Shape of allantois for cattle, sheep and pigs
Anchor shaped
Shape of allantois for dogs, cats and horses
Tube-shaped
the connecting stalk between the fetus and the placenta
UMBILICAL CORD
True or false in cattle, sheep and pigs, the umbilical cord ruptures as the fetus passes through the birth canal.
True
True or false in horses, dogs and cats, the umbilical cord normally does not break as a result of the action of the dam after the fetus has been born
False - It breaks
A structure formed by the apposition of the fetal and maternal tissues
Placenta
The formation, type and structure, or arrangement of the placenta
Placentation
Its function is to transfer nutrients and electrolytes, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to remove waste from the embryo
Placenta
2 Types of Placenta
Choriovitelline and Chorioallantoic.
when the fused vascular choriovitelline membranes become attached to the endometrium.
- common in marsupials.
choriovitelline placenta
becomes attached to the endometrium.
⁻ definitive form of placentation in higher mammals.
⁻ it may be preceded by and co‐exist with a temporary
choriovitelline placenta
chorioallantoic placenta
Characterized by uniform
distribution of villi on the
outer surface of the chorion
* Occurs in horses and pigs
Diffuse Placenta
are unique to the mare Principal source of the equine chorionic gonadotrophin (formerly
known as the pregnant mare serum gonadotrophin)
ENDOMETRIAL CUPS
Chorionic villi are restricted to cotyledons
* Occurs in ruminants
* 90-100 in sheep, 70-120 in cattle
COTYLEDONARY
the maternal contact sites
Caruncles
the cotyledon-caruncle complex
Placentome
Chorionic villi are confined to a girdle-like structure around the middle of the chorionic sac
* Occurs in carnivores
ZONARY
Chorionic villi are restricted to disc-shaped areas on the chorionic sac
* Occurs in humans, monkeys and rodents
Discoidal
microcotyledons are distributed diffusely
MICROCOTYLODENARY
Loose apposition
* Separation is easily achieved at parturition without damage to maternal tissue.
* Horses, ruminants and pigs
APPOSED, NON-DECIDUATE
- Intimate connection is formed between maternal and embryonic tissue.
- Some maternal tissue is lost with the fetal tissue at birth.
- Humans, dogs, cats and rodents
CONJOINED, DECIDUATE
- trophoblast or chorionic epithelium and uterine epithelium remain in
close contact but both retain their original layer. - marsupials ,ungulates and lemur.
- all 6 layers are intact
Epithelio-chorial
chorionic villi erode the uterine wall, so that the uterine epithelium is
ruptured and the chorionic villi comes in contact with the connective tissue of the uterine wall.
⁻ ruminants
⁻ only 5 intact layers (3 from fetal and 2 from maternal).
Syndesmo-chorial
both uterine epithelium and connective tissue is eroded so that the chorionic villi comes in contact with endothelium of maternal blood
vessel.
⁻ dogs ,cats and other carnivores.
⁻ 4 intact layers (3 from fetal and 1 from maternal).
Endothelio-chorial
⁻ uterine epithelium, connective tissue and endothelium all are eroded and the chorionic villi baths in the maternal blood.
⁻ human, primates and rodents.
⁻ only 3 intact layers: fetal/ all maternal layer’s degenerate
Haemo-chorial
⁻ foetal capillaries lie freely in maternal blood.
⁻ Rabbit.
Haemo-endothelial
- the nutritional material supplied to the embryo from the circulating maternal blood.
Haemotrophe
