Gestation: refers to the time that occurs between fertilisation+birth. It lasts 280 days.
Development of embryo have 3 stages:
Germinal: zygote transforms into a cell mass(morula) that creates another structure(blastula)
Embryonic: 3 layers of cells are formed from the bastula: inner layer(endoderm) middle layer(mesoderm) outer layer(ectoderm)
Fetal: all body structures are formed+ embryo becames a fetus.
The embryo develops in the interior of a membrane (amnion) which fills up with amniotic fluid.
The embryo feeds through the placenta
-Dilation of the cervix: while the cervix dilates, occurs a series of contractions that become more intense+frequent, pushing the fetus towards the vagina. When this stage ends, amnion ruptures(breaking waters)
-Fetus release: The fetus pushes its head out first, if this not happen the baby is extracted through caesarean section.
-Delivery of the placenta: after the baby is born, the uterus suffers more contractions. After this stage is finish, the birth ends.
Types of multiple pregnancies:
-Fraternal twins: double ovulation occurs. Sexes of the individuals can be different
-Identical twins: single zygote which have divided itselg. Genetically identical individuals.
-gonorrhea: caused by the bacterium Neisseria ghonorrhoeae. It can cause infertility+blindness in a newborn
-AIDS: caused by HIV. Its primary manifestation is a reduction in defence against microorganisms, leading to infections+tumours.