human fertilization
DESCRIPTION
A basic information to lay people & school going children about Human fertilisationTRANSCRIPT
19 Nov. 2008 Fertilization.ppt 1
Fertilization & Development
19 Nov. 2008 Fertilization.ppt 2
Coitus & Sperm Transfer
• 2-3 phases– Erection/engorgement: Parasympathetic reflex– Plateau– Orgasm: Sympathetic reflex
• Heart rate, contractility increase (pulse & BP)• Intense pleasure• Ejaculation by male
19 Nov. 2008 Fertilization.ppt 3
Fertilization
• Contact of sperm & secondary oocyte occurs in uterine tube– Sperm penetration– Oocyte completes
meiosis II– Nuclear fusion
19 Nov. 2008 Fertilization.ppt 4
Fertilization
• Sperm penetration• Why so many?
19 Nov. 2008 Fertilization.ppt 5
Fertilization
• Oocyte completes meiosis II
• Nuclear fusion– 1n + 1n 2n
19 Nov. 2008 Fertilization.ppt 6
Early Development
• Cleavage in uterine tube
19 Nov. 2008 Fertilization.ppt 7
Early Development
• Implantation– 6-7 days after
fertilization– Trophoblast forms
placenta– “Inner cell mass”
forms embryo
– (pp. 1118-1119)
19 Nov. 2008 Fertilization.ppt 8
Early Development
• Implantation– Trophoblast forms
placenta– “Inner cell mass”
forms embryo
19 Nov. 2008 Fertilization.ppt 9
Early Development• Placenta
– Provides large area for exchange of O2, CO2, nutrients, metabolic wastes between fetal and maternal blood
19 Nov. 2008 Fertilization.ppt 10
Pregnancy
• Pregnancy lasts 39-40 weeks, – 280 days from last
menstrual period– 3 trimesters
• Hormonal changes
19 Nov. 2008 Fertilization.ppt 11
Labor & Delivery• Dilation
– Cervix dilates to ~ 10 cm diameter
– Effacement– Descent of fetus into
birth canal (“Station”)• Expulsion• Placental stage
– “afterbirth”