Fertility & Early Development Flashcards
What must sperm do in the tract before fertilising the ovum?
Capacitate
What happens during capacitation (sperm maturation)?
Sperm swims through mucous and it scrapes off some molecules so that its ready for capacitation –> fertilisation
In IVF what must be done before fertilisation?
Artificial capacitate the sperm
Motility changes of sperm
- Hyper motile to get to egg
2. Slows down and swims in a star shape to hit egg
When are eggs held in meiosis 1?
When the child is unborn in her mother’s uterus
When does an egg enter meiosis 2?
When ovulated
When do eggs complete meiosis?
When fertilised
When does random selection occur?
- Half chromosomes from each parent
- Randomly selects which paternal chromosomes enter gametes
- Crossing over gametogenesis
What did Jost show?
Sexual phenotype depends on gonads
What is the testis determining gene?
SRY
Where is the SRY gene found?
On the Y chromosome
What are required for ovary development?
Oocytes
Can testes form in the absence of sperm?
Yes
Where do gonads develop?
In gonadal ridges
What are gonadal ridges precursors for?
Mesenephros (primitive kidneys) and internal tubes and ducts
What is the allantois?
Collects liquid waste from embryo and gas exchange
What are the primitive germ cell in gonad development called?
Primordial germ cells
Reaction of oogonia to oocytes
Oogonia (mitotic) ————-> oocytes (meiotic)
requires meiosis inducing substance (MIS)
What does a decline in oogonia mean in terms of FSH levels?
Decrease in FSH
What is required for oogonia —> oocytes?
Meiosis-inducing substance
Males also produces MIS from mesonephric ducts but how is it that testes are formed?
The testis cords produce meiosis preventing substance (MPS)
What happens to the testis cords at puberty?
The testis cords transform to seminiferous tubules which produce sperm throughout life after puberty
