Outer Ampulla of Fallopian Tube
-This is where fertilization occurs
Fimbriae
-Finger-like projections that "suck up" mature ovum to ampulla region.
--> "Come come to get fertilized
Mature Spermatozoa in Males
-At birth: ZERO mature sperm
-1 tsp of ejaculate = 200-500 mil sperm
Mature Ovum in Females
-At birth: abt 2 mil primary oocytes
-Fr those 2 mil abt 400-500 will mature into mature ovum
-Ovulate 400-500 mature ovum over 28d cycle
Fertilization
-1 sperm penetrated oocyte wall & fertilized mature ovum
-Sperm surround outer wall of oocyte
-Sperm releases enzyme to breakdown wall of ovum allowing 1 sperm to enter [for fertilization].
-->For fertilization to occur: intercourse 24-48h before F ovulat
Conception
-Fusing of sperm & ovum
-Chromosomes combine restoring the diploid # [46 chrom].
-->This results in the formation of the zygote
Ovum fertilized by an X-bearing sperm will...
-Form a FEMALE zygote
Ovum fertilized by a Y-bearing sperm will....
-Form a MALE zygote
Period of dividing zygote:
Pre-embryonic stg
-CLEAVAGE
-Mitotic cellular replication
-1d after conception.
Period of dividing zygote:
Pre-embryonic stg
-MORULA
-16 cell ball of cells
-3d after conception.
Period of dividing zygote:
Pre-embryonic stg
Multiplying cells separate into 2 parts:
1. TROPHOBLAST
2. EMBRYOBLAST
1. Give rise to placenta
2. Give rise to embryo
Period of dividing zygote:
Pre-embryonic stg
-Trophoblast + Embryoblast =
-Blastocyst
-4d after conception.
Period of dividing zygote:
Embryonic stg
-IMPLANTATION
-Blastocyst burrows into the endometrial tissue of uterus.
-6-10d after conception.
-->At this point it is known as an EMBRYO.
Fx of Placenta
1. Exchange of metabolic & gaseous products btwn fetal & maternal circ syst
2. Production of hormones for fetal dev
Fx of Placenta
-Entering fetal circ: ONLY NUTRIENTS! NO BLOOD! [O2, H2O, e-, carbs, lipids, protein, hormones, antibodies, virus, drugs]
-Leaving fetal circ: [CO2, H2O, urea, waste product, hormones]
-Exchange: through [simple diffusion, facilitated/active transport, pi
Fx of Placenta
Hormone: Progesterone
-Maintain pregnancy
Fx of Placenta
Hormone: Human Chorionic Gonadotropin (hCG)
-Presence & hlth of gestation (looks @ hCG levels)
Fx of Placenta
Hormone: Estriol
-Stimulates uterine growth & dev of maternal mammary glands
Fx of Placenta
Hormone: Somatomammotropin
-Provides fetus with glucose fr maternal circ syst
Umbilical cord has 3 blood vessels:
-2 arteries
-1 vein
Veins in Fetus
-Del nutrients & O2 to fetus
Arteries in Fetus
-Take CO2 away & waste products fr fetus
Part of Placenta
1. Chorionic Surface
2. Amniotic Surface
1. Maternal
2. Fetal
Fx of Amniotic Fluid
1. Prevents injury to fetus: shock-absorbing cushion.
2. Separates embryo fr other placental membranes.
-->w/o separation, can create anomalies or birth defects.
3. Provides for mvmnt which is critical for growth.
Stages of Embryo
-Embryonic stg
- 3-8 wks after conception
-Most critical time in the dev of organ syst & main external features.
-->During this stg organs are most vulnerable to anomalies caused by teratogens.
Agents assoc'd with human malformations, disruptions & deformaties:
-Drug/chemicals
-Hormones
-Infections
-Environmental/Physical elements
Anomalies:
-Malformations
-Disruptions
-Deformations
Outcome of embryo/fetus exposed to tertaogen:
-No apparent effect: d/t embryo not being embedded & not getting nutrients fr mom
-Spontaneous miscarriage
-Congenital anomalies
>inherited
>environmental factors
>inadequate maternal nutrition
-Prenatal/perinatal death
-Altered growth
-Postnatal fx'al or
Stages of Embryo
-ORGANOGENESIS
-Origin and dev of organs in the embryo
Stage of Fetus
- 9wks till pregnancy ends [24-40wks]
Fetal Circulation
-Fetal circ changes to newborn circ @ birth
-->Maternal bl & fetal bl NEVER exchange
Fetal Circulation
1. Ductus arteriosus [lungs]
2. Foramen ovale [heart]
3. Ductus venous [liver]
1. Shunts bl pass lungs
2. Allows bl to pass through heart R atrium to L atrium
3. Allows bl to bypass liver
Dizygotic Twins [Fraternal twins]
-2 mature ovum ovulate @ same time & fertilized by 2 sperm.
-2 placentas
-2 chorions [dichorionic]
-2 amnions [diamniotic]
-diff genotype
-2 genetically diff offspring [like bro & sis born @ the same time]
-can be same sex
Monozygotic Twins [Identical twins]
-1 fertilized ovum/1 sperm
-Blastocyst divides-->2 Blastocyst w/same chromosomal makeup
-Same sex
-Same genotype
Monozygotic Twins [Identical]
A.
-Blastocyst: Divides before implantation
-2 placenta
-2 chorion
-2 amnion
B.
-Blastocyst: Divides after implantation
-1 placenta
-1 chorion
-2 amnion
C.
-Blastocyst: Doesn't fully divide
-1 placenta
-1 chorion
-1 amnion
-->Conjoined Twins: Share same g
Key Points
-Mitosis
-Body cells replicate for growth and dev & cell replacement of organism
Key Points
-Meiosis
-Gametes are formed for reproduction of the organism
Key Points
-Human gestation lasts abt ___d after last menstrual per OR ___d after conception
-280 days
OR
-266 days
Key Points
-Fertilization occurs in the ______ tube within __h of ovulation
-uterine
-24h
Key Points
-Zygote undergoes mitotic divisions, creating a __-cell ____
-16 cell
-morula
Key Points
-Implantation begins __d after fertilization
-6d
Key Points
-____ syst and ____ features develop during ____ period __ to __wk after fertilization
-Organ syst
-External features
-Embryonic
-3 to 8wk
Key Points
-Refinement of strx & fx occurs during the ___ per, & fetus becomes capable of extrauterine survival
-Fetal
Key Points
-During critical per in human dev, the embryo & fetus are vulnerable to environmental _____.
-Teratogens