Anatomy and Physiology of Pregnancy Flashcards
How is sperm lost from the females tract?
- phagocytosis
-retrograde loss - passage from the vagina through the cervix
How does sperm transport?
mare/sow/bitch = short distance into uterus
cow/ewe = secretions of the cervix eliminates non-motile sperm
What is sperm capacitation?
spermatozal capacitaion is required for sperm to be fertile
- occurs in female tract
- plasma membrane of the head undergoes major change
-acrosome left with exposed molecules
Where does fertilisation occur?
The apppulla of the fallopian tube
How does fertilisation occur?
- corona retina penerated
- sperm binds to zona pellucida
- acrosome reaction occurs
-penetration of the zona pellucida by enzymes
-membranes fuse - cortical reaction occurs
- sperm molecules decondense
-formation of pronuclei
pronuclear fusion causing a zygote
How does fertilisation occur?
- corona retina penerated
- sperm binds to zona pellucida
- acrosome reaction occurs
-penetration of the zona pellucida by enzymes
-membranes fuse - cortical reaction occurs
- sperm molecules decondense
-formation of pronuclei
pronuclear fusion causing a zygote
What is a zygote?
fertalised ovum
what is an embryo?
early stages of development
what is a foetus?
potential offspring (recognisable)
what is a conceptus?
either an embryo or foetus
What is a blastomere?
- Forms from a zygote undergoing mitotic divisions
- blastomeres are individual cells in early devisions
- totipotent (able to give rise to any cell type)
What is a morula?
- early development
- ball of cells (blastomere development)
- separates into different populations
-fluid begins to move into the embryo
-moves into the uterus
How does a morula develop to a blastocyst?
- blastocoel forms (yolk sac)
-inner cells and trophoblast cells (placenta) form - cells begin differentiation
- mitosis continues + more fluid
- proteolytic enzymes weaken zona pellucida
What is the difference of contraception seen in the mare?
- capsule forms between zona pellucida and trophoblast at day 5 (blastocyst)
What are the embryonic germ layers seen in early development?
-ectoderm (nervous system/skin and hair)
-mesoderm (muscle/skeleton/cardiovascular/reproductive systems)
-endoderm (digestive system/lungs/endocrine system)
What forms the placenta in early development?
-chorion
-allatois
(forms featal portion) (blasocyst)
What is embryonic organ development divided into?
- gastrulation (development and organisation of the three germ layers)
- neurulation (beggining of the formation of CNS)
In the cow and ewe how is pregnancy recognised?
- inferon-t secreted by trophoblast cells act on the endometrium preventing oxytocin reception by endometrial cells
In the sow how is a pregnancy recognised?
- two conceptous per horn
- oestrodiol secreted from conceptous
How does the coceptus move in the mare compared to other species?
other species = trophoblast elongation
mare = circles around the uterus through uterine contractions (days 12-14)
What are the phases of implantation?
- shedding of the zona pellucida
- precontact/blastocyst orientation
-apposition
-adhesion - endometrial invasion/penetration (only bitch and queen)
How is the zona pellucida shed before implantation?
-blastocyst hatching
How does phase 2 of implantation occur?
- no cellular contact between endometrium and trophoblast
-blastocyst elongates (in mare only after capsule loss)
-immobilisation of conceptus
-moves to prepare for apposition
How does apposition occur at implantation?
-trophectoderm becomes closely associated to endometrium
Ewe/cow/sow = Trophoblastic microvilli invade endometrial glands
Ewe/cow = Alterations to endometrium, cranucles become oedematous (fluid increased)
Mare = chronicle girdle forms/ thickening on outer trophoblast/cells enlarged and invade into endometrial glands
How does apposition occur at implantation?
-trophectoderm becomes closely associated to endometrium
Ewe/cow/sow = Trophoblastic microvilli invade endometrial glands
Ewe/cow = Alterations to endometrium, cranucles become oedematous (fluid increased)
Mare = chronicle girdle forms/ thickening on outer trophoblast/cells enlarged and invade into endometrial glands
what occurs at adhesion during implantation?
- intergration of maternal and foetal tissue
-placentation begins
What is placentation?
- organ that provides protection/environmental regulation (nutrient/waste/gaseous exchange)
- composed of chorion and endometrium
-distribution of chronic villi and erosion of the foetal to maternal interface is relied upon
What is placentation?
- organ that provides protection/environmental regulation (nutrient/waste/gaseous exchange)
- composed of chorion and endometrium
-distribution of chronic villi and erosion of the foetal to maternal interface is relied upon
What is the erosion of the foetal to maternal interface?
number of placental layers between maternal and foetal blood supply
What is epitheliochorial during placentation?
-epithelium and chronic villi stay intact
What is endotheliochorial during placentation?
erosion of the endometrium
What is haemochorial during placentation?
chorion in direct contact with maternal blood
How does adhesion occur in the mare?
-endometrial cups formed by binucleate cells/ secretes equine chorionic gonadotrophin
-foetal allantochorion spread through uterus by day 90
how does adhesion occur in the sow?
trophectoderm attaches to uterine wall (day 18-20)
How does adhesion occur in ruminants?
-placentomes (cotyledon - foetal side caruncles-maternal side)
- can have uninucluete and binuclete cell types
How does implantation occur in the bitch and queen?
-erosion of the endometrium to form the endotheliochorial placenta
