Development of the fertilized ovum Flashcards
Menarche
Beginning of menstruation
Occurs at about age 11 - 15 years
Climacteric
a period of years during which the woman’s ability to reproduce gradually declines
Menopause
the final menstrual period
Phases of ovarian cycle
Follicular, ovulation and luteal
Phases of menstrual cycle
Menstrual, proliferative, secretory
What does FSH do?
Stimulate the follicles in the ovary to mature.
Once it matures it becomes the graafian follicle
What does LH do?
Causes the graafian follicle to release the ovum
Stages of fetal development
- Morula
- Blastocyst
- Embryonic disk
- Gastrulation
Morula
Solid mass of cells resulting from cleavage after 3 days
Blastocyst
Ball of cells formed from morula after 5 days
Embryonic disk
Inner mass of cells of blastocyst
Gastrulation
Embryo composed of three tissues:
Ectoderm, mesoderm and endoderm
Ectoderm
Outer layer which gives rise to the nervous system and outer layers of integumentary system
Mesoderm
Middle layer
Muscles, organs of circulation, reproduction, excretion and skeleton are derived from it
Endoderm
Inner layer
Gives rise to the lining of the digestive tube and organs derived from it
Four weeks
The four-chambered heart beats, sending blood through simple vessels.
Intestines, liver, pancreas, lungs, and limb buds can be
seen.
The embryo is about 1/5
inch long.
Eight weeks
At this stage, the face and neck take shape, the back straightens, and fingers and toes can be differentiated clearly.
The embryo starts to move.
It is now around 1 to 1-1/5 inch in length.
Monozygotic twins
A single fertilized egg, or zygote, forms an embryo that splits into two. Each develops into a fetus.
The two have the same genes and sex and share one placenta. They look alike and are known as “identical”
twins
Dizygotic twins
Two eggs are released and both are fertilized.
Two zygotes form, implant, and develop, resulting in the birth of dizygotic (or fraternal) twins.
Trophoblast
forms early embryo, fetal membranes and placenta after five to seven days
Embryo
the developing human from fertilisation to the eighth week of pregnancy
Placental functions
IRENE
I - Immune
R - Respiratory
E - Endocrine
N - Nutritional
E - Excretory
Function of membranes and amniotic fluid
• Protection from trauma
• Maintenance of temperaturr
• Amniotic fluid allows free movement of the fetus
• Allows for fetal growth and prevents body parts sticking to the membranes
• Allows fetus to prepare for swallowing and breathing when baby is born
• Fetus helps maintain fluid volume by swallowing and passing it out as urine
Human chorionic gonadotropin
Maintains corpus luteum until week 12
Secreted by placenta
Estrogen/progesterone
Source: Corpus luteum/placenta
Stimulate and maintain uterine lining, inhibit FSH and LH, ihibit uterine contractions, enlarge reproductive organs
Estrogen/progesterone
Source: Corpus luteum/placenta
Stimulate and maintain uterine lining, inhibit FSH and LH, ihibit uterine contractions, enlarge reproductive organs
Human chorionic somatomammotropin
Human placental lactogen
Source: placenta
Mammary gland development, insulin sparing effects in mother, weak GH type effect
Human chorionic thyrotropin
Source: placenta
Increases size/activity of maternal thyroid and parathyroid glands
Aldosterone
Source: adrenal cortex
Increase fluid retention
