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

Corona radiata

Zona pellucida

Ovum and Sperm

sperm headsperm head

Fertilization

Fertilization

metaphase of second meiotic division

first polar body

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

Approach of

Pronuclei

1. Nucleic membranes of thepronuclei dissolve

2. Microtubules of the mitotic spindle

Formation of the

Zygote

Formation of the

Zygote

CleavageCleavage

CleavageCleavage

Implantation

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

syncyticotrophoblast

cytotrophoblast

Amniotic cavity

epiblast

Yolk sac

hypoblast

Gastrulation

Primary Germ LayersPrimary Germ LayersEctodermEctodermEndodermEndodermMesodermMesoderm

Organogenesis

Differentiation of primary Differentiation of primary germ layers into tissues germ layers into tissues

and organs.and organs.

Embryonic Development

Embryonic Development

FetalDevelopment

FetalDevelopment

Development of Reproductive

Organs

The Placenta

The Placenta

6 months ultrasound

Changes in Uterus

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

Dilation Stage

Expulsion Stage

Placental Stage

Hormones Involved in Hormones Involved in LaborLabor

EstrogenEstrogenFetal OxytocinFetal Oxytocin

Placental ProstaglandinsPlacental ProstaglandinsMaternal OxytocinMaternal Oxytocin

RelaxinRelaxin

Labor Hormones

Mammary Gland

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

Birth Control MethodsBirth Control Methods

• Barrier Methods- Condom- Vaginal pouch- Diaphragm

• Spermicides

• Periodic Abstinence- Rhythm Method

• Abortion