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
