BIOSC-116 Lecture Notes - Lecture 23: Zygote, Natural Family Planning, Zona Pellucida
26 Aug 2020
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This prevents polyspermy: nuclear fusion = the sperm and the egg nuclei join to form the zygote. Development stages i. e. development of the baby: early development (of the zygote, mitosis = cleavage. Rapid mitotic divisions occur so that there are more and more cells but they get progressively smaller. During cleavage, the baby is traveling from the fallopian tubes: arrival at the uterus occurs, blastocyst formation the blastocyst contains 2 layers of cells: Trophoblast this will become the placenta. Right before birth, surfactant is produced in the lungs. Birth control: surgical methods = vasectomy(males) and tubal ligations (females, barrier methods = condom, diaphragm, cervical cap. These prevent the entry of sperm into the female tract: hormonal inhibition of gamete production = oral contraceptive pill, depo. These contain a synthetic progesterone (progestin) which acts like the body"s progesterone to cause negative feedback inhibition of fsh and lh release, which would then prevent ovulation.
