Dr. Chibogu Flashcards
Oogenesis, ovulation, coitus
What is oogenesis
This is the production of the female sex gament
What are the stages of ovum or oicyte developments
Primordial germ cell – Oogonium— primary oocytes — Secondary oocytes— ovum
Where does oogenesis start from and when does it end
It start prenatally and end at the point of fertilization
The whole process of oogenesis can be described in 3 stages
Stage 1 : Differentiation from primodal germ cell to — Oogonium
Stage 2 oocytogenesis
Oogonia / oogonium ____(mitotic division)– primary oocytes
The primary oocyte begin meiosis division and is arrested at prophase stage
Stage 3 Ootidogenesis
Ootic – chromosome has been half
The arrest has been removed and the first meiosis division is completed
To produce secondary oocytes
Secondary oocytes— undergoes 2nd meiosis to give rise to ovum at fertilization
What us formed after the first meiosis
The Secondary oocytes—and 1polar cell
What is the difference between polar body and oocytes
Cytoplasm size
Nuclear to cytoplasm ratio
What is formed after the second meiosis division
Ovum and 3 polar bodies
The total number primary oocyte in every mammal is determined or known at
Birth
Developments from primary oocyte occurs when ?
Under the influence of ?
Occurs at Puberty
Influence of GnRH
What happens to primary oocytes— at birth
They are encased in primodal follicle
What has a characteristics small shape and one layer of follicular cell (SQUAMOUS cell)
What is the arrest phase (prophase 1 ) also called
Diplotene stage
What causes the arrest at the prophase stage
Oocytes maturation inhibitor (OMI)
What happens to follicle at Puberty
They developed from primodal to primary to
secondary to
graffian or pre- ovulatory follicle
The second meiosis division get arrested at what stage
When is it released
Metaphase 2
Released at fertilization
What is the end point of folliculogenesis
The release of secondary oocyte from the matured follicle
What are the two types of ovulation based on stimulus that triggers the release of oocytes
Spontaneous ovulation
Induced ovulation
What is spontaneous ovulation
Spontaneous ovulation occurs at natural events and occurs due to cycles
Without any extraneous or exogenous influence
What ate the characteristic of spontaneous ovulation
1 Occurs at regular intervals
2. Hormonally controlled
LH. Leuthenizine hormone is what triggers ovulation
3. Estrogen is very important to the release of LH
Examples of spontaneous ovulators
Cow , sheep, Goat, Dog
Induced ovulation
There must be an external stimuli that triggers the increase of protrution of follicles
Example of the chemical that can induce ovulation
Coitus
Chemical stimulus
Semen in the reproductive tract
Examples of induced ovulators
Rabbit, cat, camel, elama
Factors that affect ovulation rate
The rate of ovulation is genetically determined
Factors that affect ovulation
Nutrition
Age
Season (seasonal breeder)
Social effect
Male effect
What us coitus
Interaction btw male and female corpulatory organs
What is corpulation
Physical union of male and female corpulatory organs involving intromission, thrusting with the aim to release semen in the reproductive tract
Site of semen release
Horse – deep to the iterus
Cow —- at the vaginal
Pig – dip even as far as uterus
What us fertilization
The union of male and female gament to form Zygote
What are the 6 stages of fertilization
- Spermatozoa and oocyte engagement
- Acrosome reaction
- Fusion of membrane
- Oocyte activation
- Formation of pronuclei
- Symgamy
Cortical reaction
This involves the movement of organelles (perisome, vacoules) to the peripheral of the cell membrane lead to zonal block
Zonal blocks
Chemical interaction with the zonal pellucida that inhibits the engagement of any other sperm interaction
Preventing polyspermy
Remember histosome
Yes
This are protein that pack the chromosome
Prof. Mrs alawa mention it
When is the acrosome reaction said to be completed
Acrosome reaction is completed when the spermatozoa membrane lies within the perivitaline space
Note about the sperm cell during fertilization
The sperm cell do not release their flagellum and mitochondria into the egg
The female mitochondria ends up powering the Zygote
What do you see that confirm fertilization
Tail visibility
Presence of 2 pronuclei in cytoplasm
Cell division (2 cell in cleavage)
Then presence of polar bodies is suggestive
What are the anomalies of fertilization
Polyspermy
Digynic polyploid
What is polyspermy
Occurs when more than one sperm fertilize an ovum or egg
This results in an embro with two many chromosome which is usually not viable
Digenic polyploidy
Digynic polyploidy happens when an egg with extra set if chromosome is fertilized by a normal sperm
This lead to an embro with 3 set of chromosome instead of 2 Chromosome
Condition leads to miscarriage or serious development issues
Fertilization anomaly
Polyploidy (diadrenic polyploidy)
Due to fertilization defects
Polyploidy (digynic polyploidy)
Due to first meiosis failure
Monoploidy
Embroyonic developments
Cleavage (division of cells without increase in the space)
Blastocysts is formed
What is hatching
Hatching (breaking out of zonal pellucida )
What are the stages of implantation
There are 4 stages
Hatching
Apposition
Adhesion
Invasion (primates)
Types of implantation
- Interstitial
involves burring into the endometrium - Eccentric
The embro is said to be absorbed in a depression
- Centric
the embro expands becomes aposed with the wall of the endometrium
(domestic animals)
