Human Development Vocabulary
• Pregnancy- an event that occurs from fertilization to birth
• Conceptus- developing offspring• Gestation period- time from last
menstrual period until birth (~280 days)
• Embryo- from fertilization through week 8
• Fetus- from week 9 through birth
Stages of Development
Pre-Embryonic DevelopmentPre-Embryonic DevelopmentFertilizationFertilizationCleavageCleavage
Embryonic DevelopmentEmbryonic DevelopmentGastrulationGastrulationOrganogenesisOrganogenesis
Fetal DevelopmentFetal Development
Fertilization Facts!
• Oocyte is viable for 12-24 hrs after ovulation
• Sperm are able to fertilize oocyte for up to 48 hrs
• In order for fertilization to occur, coitus must take place 48 hrs before-24 hrs after ovulation
• Fertilization usually occurs when oocyte is 1/3 way down fallopian tube
Fertilization
1. Mitotic spindle with chromatids
2. 1st polar body3. Pellucid zone4. Perivitelline space5. Cell membrane of the
sperm 6. Kinocilium7. Nucleus (compact) of
the sperm8. Proximal centrosome
of the sperm
Fertilization
1. 1st polar body 2. Nucleus of the sperm3. Proximal centrosome
of the sperm4. 2nd polar body
(being formed)5. Remainder of the
mitotic spindle
polar bodies
Fertilization
1. Sperm pronucleus2. Oocyte pronucleus3. Centrosome brought in by the spermatozoon
1. Sperm pronucleus2. Oocyte pronucleus3. Paternal centrosome4. "Inner bodies"5. Maternal astral microtubule
Approach of
Pronuclei
1. Nucleic membranes of thepronuclei dissolve
2. Microtubules of the mitotic spindle
Formation of the
Zygote
Implantation
• Blastocyst floats for 2–3 days
• Implantation begins 6–7 days after ovulation– Trophoblast adheres to a site with the
proper receptors and chemical signals
– Inflammatory-like response occurs in the endometrium
Figure 28.5a
(a)
Uterine endometrialepitheliumInner cell mass
Trophoblast
Endometrium
Blastocyst cavity
Lumen of uterus
Implantation
• Trophoblasts proliferate and form two distinct layers1. Cytotrophoblast (cellular trophoblast): inner
layer of cells
2. Syncytiotrophoblast: cells in the outer layer lose their plasma membranes, invade and digest the endometrium
Figure 28.5c
(c)
Endometrial stromawith blood vesselsand glandsSyncytiotrophoblastCytotrophoblast
Inner cell mass(future embryo)
Lumen of uterus
Implantation
• The implanted blastocyst is covered over by endometrial cells
• Implantation is completed by the twelfth day after ovulation
Organogenesis
Differentiation of primary Differentiation of primary germ layers into tissues germ layers into tissues
and organs.and organs.
Metabolic changes during pregnancy• Caloric intake increases 300 + Kcal/day• Elevated PTH and Vitamin D• HPL causes mom to metabolize fatty acids,
leaving glucose for fetus• 10% of mothers will present with gestational
diabetes• 50% of those with gestational diabetes will
later develop Type II Diabetes
Physiological changes during pregnancy
Almost every body system is altered by the physiological burden of the fetus
• Heart: CO›30%• Lungs: TV ›30-40%• GI tract: appetite up; motility down• Uterus: 80g-› 1200 g• Urinary: increased renal flow and urination
Stages of Childbirth or Stages of Childbirth or LaborLabor
Dilation StageExpulsion StagePlacental Stage
Hormones Involved in Hormones Involved in LaborLabor
EstrogenEstrogenFetal OxytocinFetal Oxytocin
Placental ProstaglandinsPlacental ProstaglandinsMaternal OxytocinMaternal Oxytocin
RelaxinRelaxin
Hormones Involved in Hormones Involved in LactationLactation
Estrogen & ProgesteroneEstrogen & ProgesteroneProlactin Releasing HormoneProlactin Releasing Hormone
ProlactinProlactinHuman Chorionic SomatomammotropinHuman Chorionic Somatomammotropin
OxytocinOxytocin
Components of breast milk
• Immune cells: neutrophils, macrophages, Killer T cells, and plasma cells
• Molecules: Antibodies (IgA), lysozyme, & Interfereons
• Nutrition: lipids, carbs, and protein
Birth Control MethodsBirth Control Methods
• Abstinence
• Sterilization - Vasectomy- Tubal ligation
• Hormonal Methods- Oral contraceptives- Emergency contraception- Norplant- Dep-provera- Vaginal ring