Week 1 - Origin of the Sexes Flashcards
Where and when are primordial germ cells formed?
Primordial germ cells are formed in the epiblast during the second embryonic week
Approximately how many ova are produced over a female’s entire reproductive life span?
400
How long after ovulation is the ova available for fertilisation by sperm?
36 hours
Approximately how much sperm does a young man produce in a second?
7000
What types of oestrogens are produced by the ovaries?
- Oestradiol - main
- Oestrone
- Oestriol
Name the main reproductive hormones produced by the placenta.
- Human chorionic gonadotrophin
- Human placental lactogen
- Oestrogens - oestrone, oestradiol, oestriol
- Progesterone
When are germ cells identifiable in the embryo post-conception?
3-4 weeks post conception
Where do germ cells arise?
In the epithelium of the yolk sac near the base of the developing allantois
When do the primordial germ cells migrate to the primordial gonads (somatic mesenchymal tissue)?
6 weeks post conception
Where do the primordial gonads lie?
Superficially and medially to the mesonephric tissue
Which tissue forms the primitive medullary cords?
Columns of cells from the mesonephros
Which tissue forms the sex cords?
Columns of cells from the coelomic epithelium
What cells give rise to Sertoli cells?
Mesodermal cells
Which cells express the SRY gene?
Sertoli cells express the SRY gene - expressed only in males
State the components of the female external genitalia.
- Vagina
- Vestibule
- Labia majora
- Labia minora
- Clitoris
