OB Final Exam New Study Guide Review Solution 2024
Chapter 10: Fetal Development and Genetics
❖ Stages of Fetal Development
➢ Fetal development
■ Measured in weeks. Approximately 40 weeks; 9 calendar months or 266
to 280 calendar days.
➢ Pre-embryonic stage
■ Begins with fertilization (conception), around 2 weeks after the last normal
menstrual period (in a 28 day cycle), through the second week.
❖ Stages of Fetal Development
➢ Prior to fertilization, the ovum & the sperm undergo the process of meiosis.
❖ Stages of Fetal Development
➢ Zona pellucida – clear protein layer around the ovum which disappears in about 5
days.
➢ Each nucleus contains a haploid number of chromosomes (23), the union restores the
diploid number (4G). When the ovum is fertilized by the sperm- it becomes one cell
(zygote) & begins the process of new life.
➢ The sex of the zygote is determined by the sperm.
, Fertilization
➢ The developing blastocyst needs more food & oxygen to keep growing.
➢ The trophoblast attaches itself to the surface of the endometrium for further
nourishment.
➢ Implantation normally occurs in the upper uterus (fundus), where a rich blood supply
is available. There are also strong muscular 1bers, which clamp down on blood vessels
after the placenta separates from the inner wall of the uterus, after birth. The lining is
thickest here so the placenta cannot remain attached.
❖ Summary of Pre-embryonic Development
➢ Fertilization takes place in the ampulla of the fallopian tube (outermost or upper).
➢ Union of sperm & ovum – a zygote (4G chromosomes).
➢ Cleavage cell division continues to form a morula (mass of 1G cells).
➢ Blastocyst
■ The inner cell mass forms the embryo & amnion.
■ Trophoblast – The outer cell mass forms the placenta & chorion.
➢ Implantation occurs 7 to 10 days after conception in the endometrium.
❖ Embryonic Layers
➢ Three embryonic layers of cells are formed.
➢ Ectoderm: (outer) forms the central nervous system, special senses, skin, & glands,
(amnion).
Chapter 10: Fetal Development and Genetics
❖ Stages of Fetal Development
➢ Fetal development
■ Measured in weeks. Approximately 40 weeks; 9 calendar months or 266
to 280 calendar days.
➢ Pre-embryonic stage
■ Begins with fertilization (conception), around 2 weeks after the last normal
menstrual period (in a 28 day cycle), through the second week.
❖ Stages of Fetal Development
➢ Prior to fertilization, the ovum & the sperm undergo the process of meiosis.
❖ Stages of Fetal Development
➢ Zona pellucida – clear protein layer around the ovum which disappears in about 5
days.
➢ Each nucleus contains a haploid number of chromosomes (23), the union restores the
diploid number (4G). When the ovum is fertilized by the sperm- it becomes one cell
(zygote) & begins the process of new life.
➢ The sex of the zygote is determined by the sperm.
, Fertilization
➢ The developing blastocyst needs more food & oxygen to keep growing.
➢ The trophoblast attaches itself to the surface of the endometrium for further
nourishment.
➢ Implantation normally occurs in the upper uterus (fundus), where a rich blood supply
is available. There are also strong muscular 1bers, which clamp down on blood vessels
after the placenta separates from the inner wall of the uterus, after birth. The lining is
thickest here so the placenta cannot remain attached.
❖ Summary of Pre-embryonic Development
➢ Fertilization takes place in the ampulla of the fallopian tube (outermost or upper).
➢ Union of sperm & ovum – a zygote (4G chromosomes).
➢ Cleavage cell division continues to form a morula (mass of 1G cells).
➢ Blastocyst
■ The inner cell mass forms the embryo & amnion.
■ Trophoblast – The outer cell mass forms the placenta & chorion.
➢ Implantation occurs 7 to 10 days after conception in the endometrium.
❖ Embryonic Layers
➢ Three embryonic layers of cells are formed.
➢ Ectoderm: (outer) forms the central nervous system, special senses, skin, & glands,
(amnion).
