CONCEPTION AND FETAL DEVELOPMENT
Menstrual Cycle
● Follicular Phase
○ 1-14 days in cycle
○ INCREASE in FSH and LH
○ Graafian follicles contain oocyte which are immature ovum that starts growing
● Ovulatory Phase
○ Middle of 28–day cycle and 2 days before ovulation
○ LH increases sharply, FSH rises
○ Ovum matures and released- OVULATION
● Luteal Phase
○ Corpus luteum releases progesterone
○ If ovum is fertilized–HCG secreted/ and corpus luteum will help maintain pregnancy
○ If ovum is NOT fertilized- Decreased FSH and LH and uterine lining breaks down
● CYCLE RESTARTS
Endometrial Cycle with Menstruation
● Proliferation Phase
○ First half: mature ovum is released
○ Thickening of endometrium
○ Thin mucous released to help sperm reach uterus
● Secretory Phase
○ Second half of cycle
○ Uterus gets thicker
○ Nourishment released for Fertilization
● Menstrual Phase
○ No fertilization
○ Endometrium necrosis
○ Menstrual flow
S/Sx of Ovulation
● Increase body temp
● Mittelschmerz
● Cervical mucus changes: Amount increased/ thin, watery, and clear/ Stretchable: Spinnbarkeit/ Alkaline
Ovulation
● One ovum per month is discharge from ovary
● Its transported into the fallopian tube where it begins its journey through the tube in search for the sperm
● ONLY FOR 24 HOURS
, Spermatozoa
● are the male sex cells that carry genetic material.
● Capacitation occurs as the sperm travels to the egg.
● Acrosome Reaction
○ Sperm release an enzyme HYALURONIDASE as they swarm around the ova to allow one sperm to
penetrate the ovum for fertilization.
○ Viable for 1-2 days
Fertilization
● Occurs when one sperm enters the ovum and the two nuclei containing the parent chromosomes unite.
○ Usually occurs in the DISTAL PORTION OF THE FALLOPIAN TUBES
○ The 23 chromosomes from the sperm mingle with the 23 chromosomes from the ovum
○ Zygote is formed and ready for cell division.
Cellular Multiplication
● The ZYGOTE, begins its travel through the fallopian tube toward the uterus
● Cellular, mitotic division
● Morula (12-16 cells forms–a solid fluid filled cavity within the cell mass.
○ Inner solid cell mass is called Blastocyst
○ Outer cell mass that surrounds the cavity is the Trophoblast
Implantation
● Zygote travels for 3-4 days
● Day 10: Zygote implants–Small finger-like projections extend from the trophoblast and burrow into the
endometrium.
● Once the Zygote implants, it secretes hCG to signal the beginning of pregnancy
○ hCG then signals corpus luteum to continue the secretion of estrogen and progesterone.
● Implantation is dependent on a continued supply of estrogen and progesterone.
● Implantation enables the blastocyst to absorb nutrients from the endometrium
● Implantation site is important b/c this is where the placenta will develop.
● Normal: Upper uterus/fundus
Development of the Fetus
● Pre-embryonic Period (Zygote)
○ Weeks 1-2
○ Cellular division
● Embryonic Period
○ Weeks 3-8
○ ORGANOGENESIS
● Fetal Period
○ Weeks 9-40
○ Rapid growth and refinement in structures and functions of systems.
Menstrual Cycle
● Follicular Phase
○ 1-14 days in cycle
○ INCREASE in FSH and LH
○ Graafian follicles contain oocyte which are immature ovum that starts growing
● Ovulatory Phase
○ Middle of 28–day cycle and 2 days before ovulation
○ LH increases sharply, FSH rises
○ Ovum matures and released- OVULATION
● Luteal Phase
○ Corpus luteum releases progesterone
○ If ovum is fertilized–HCG secreted/ and corpus luteum will help maintain pregnancy
○ If ovum is NOT fertilized- Decreased FSH and LH and uterine lining breaks down
● CYCLE RESTARTS
Endometrial Cycle with Menstruation
● Proliferation Phase
○ First half: mature ovum is released
○ Thickening of endometrium
○ Thin mucous released to help sperm reach uterus
● Secretory Phase
○ Second half of cycle
○ Uterus gets thicker
○ Nourishment released for Fertilization
● Menstrual Phase
○ No fertilization
○ Endometrium necrosis
○ Menstrual flow
S/Sx of Ovulation
● Increase body temp
● Mittelschmerz
● Cervical mucus changes: Amount increased/ thin, watery, and clear/ Stretchable: Spinnbarkeit/ Alkaline
Ovulation
● One ovum per month is discharge from ovary
● Its transported into the fallopian tube where it begins its journey through the tube in search for the sperm
● ONLY FOR 24 HOURS
, Spermatozoa
● are the male sex cells that carry genetic material.
● Capacitation occurs as the sperm travels to the egg.
● Acrosome Reaction
○ Sperm release an enzyme HYALURONIDASE as they swarm around the ova to allow one sperm to
penetrate the ovum for fertilization.
○ Viable for 1-2 days
Fertilization
● Occurs when one sperm enters the ovum and the two nuclei containing the parent chromosomes unite.
○ Usually occurs in the DISTAL PORTION OF THE FALLOPIAN TUBES
○ The 23 chromosomes from the sperm mingle with the 23 chromosomes from the ovum
○ Zygote is formed and ready for cell division.
Cellular Multiplication
● The ZYGOTE, begins its travel through the fallopian tube toward the uterus
● Cellular, mitotic division
● Morula (12-16 cells forms–a solid fluid filled cavity within the cell mass.
○ Inner solid cell mass is called Blastocyst
○ Outer cell mass that surrounds the cavity is the Trophoblast
Implantation
● Zygote travels for 3-4 days
● Day 10: Zygote implants–Small finger-like projections extend from the trophoblast and burrow into the
endometrium.
● Once the Zygote implants, it secretes hCG to signal the beginning of pregnancy
○ hCG then signals corpus luteum to continue the secretion of estrogen and progesterone.
● Implantation is dependent on a continued supply of estrogen and progesterone.
● Implantation enables the blastocyst to absorb nutrients from the endometrium
● Implantation site is important b/c this is where the placenta will develop.
● Normal: Upper uterus/fundus
Development of the Fetus
● Pre-embryonic Period (Zygote)
○ Weeks 1-2
○ Cellular division
● Embryonic Period
○ Weeks 3-8
○ ORGANOGENESIS
● Fetal Period
○ Weeks 9-40
○ Rapid growth and refinement in structures and functions of systems.
