Gametogenesis and fertilisation Flashcards
why’d o we study human embryology? (5)
- to understand our parental origin
- understanding birth defects or congenital abnormalities
- foundational knowledge for obstetrics and paediatrics specialities
- understanding illness or disease with development origin
- knowledge for patients on issues relating to reproduction, birth defects and prenatal development, in-vitro fertilisation, stem cell and cloning
how many trimesters are there in the prenatal period?
3
which weeks do most morphogenic abnormalities develop?
3-7 weeks
when does the CNS and heart begin to develop?
middle week 6
when do the arms and legs develop
week 8
when do the eyes begin to develop
middle of week 8
when do the external genitals develop
weeks 9-38
what is gametogenies
the process of the production of male and female gamete or sex cells (sperm and egg) from the primordial germ cells via meiotic cell division in the gonads (testes and ovaries)
what do gametes develop from
the primordial germ cells
what kind of cell division forms the gametes
meiotic
what are the gonads
the testes and the ovaries
what are PGCs
primordial germ cells - specialised stem cells that give rise to the germ line and are formed a generation earlier when the parents were embryos
( we are handed over reproductive ability by parents before we were born)
stem cell
an undifferentiated cell that has the ability to form specialised cell types - embryonic or adult stem cells
embryonic stem cells are
pluripotent
adult stem cells are
multipotent
pluripotent cells
have the ability to form all mature cell types in the body except placental and extra embryonic cells - cannot form the whole organism
what can pluripotent cells NOT form
placental and extra embryonic cells
multipotent cell
ability to form more that one closely related mature cell types in the body but not as varied as pluripotent
eg - cord, blood/bone marrow stem cells from erythrocyte, leucocyte, platelet.
totipotent cell
has ability to form all differentiated cell types in the body including the placental and extraembryonic membrane cells. It could form a whole organism
which is the most undifferentiated stem cell.
totipotent
errors in gametogenesis can lead to
chromosomal abnormalities that could result to birth defects or spontaneous abortions.
errors in spermatogenesis can lead to
a number of spermatozoa morphological abnormalities that could affect male fertility – Sperm count clinical investigation.
what does a sperm count show
number/quality - viability and agility
what do basic contraceptive methods target?
physiological processes and anatomical framework relating to release of gametes – hormonal induction of hostile environment
male infertility could result from
the quality and quantity of spermatozoa ejaculated.
Female infertility could result from
a number of causes including physiological and anatomical factors
Infertility in both male and female could be treated with
Infertility in both male and female could be treated with
when totipotent cells split in the womb
monozygotic twins
what % f birth are twins in natural fertilisation
3%
How are monozygotic twins (identical) twins formed
Form by splitting of a single fertilized zygote at various stages of development.
what % of natural births are monozygotic twins
0.4%
Monozygotic (Identical) twins
Monozygotic (Identical) twins
what are fraternal twins
dizygotic twins - not genetically identical
when do dizygotic twins occur
Form when two separate oocytes are produced simultaneously in the same menstrual cycle and are fertilized by different spermatozoa.
what % of natural births are dizygotic twins
1.2%
are dizygotic twins always going o be the same sex
no, they may or mayn’t be the same sex
6 methods of assisted reproductive technologies for infertility treatment
- In vitro fertilisation (IVF)
- gamete intrafallopian transfer (GIFT)
- artificial insemination by donor (AID)
- Zona drillin (ZD)
- Subzonal insemination (SUZI)
- intracytoplasmic sperm injections (ICSI)
In Vitro Fertilization (IVF)
Sperm and eggs are placed in a laboratory dish to fertilize.
Gamete Intrafallopian Transfer (GIFT)
Sperm and eggs are injected into the uterine tube to fertilize
Artificial Insemination by Donor (AID):
Sperm is injected into the cervix or uterus or uterine tube
Zona Drilling (ZD):
A microsurgical technique that facilitates sperm penetration into the egg with the use of acid tyrode’s solution or enzyme such as trypsin or pronase. Fertilized egg is transferred into the uterus.
Subzonal Insemination (SUZI)
A procedure where spermatozoa are injected into the perivitelline space that surrounds the egg membrane. The fertilized egg is later implanted into the uterus.
Intracytoplasmic Sperm Injection (ICSI):
A procedure where a single sperm is directly injected into an egg. The fertilized egg is then implanted into the uterus.
