18. Embryology 1&2 Flashcards
What is the development of the human?
Pre-embryonic phase: 0-3 weeks
Embryonic phase: 4-8 weeks
Foetal phase: 9-40 weeks
What is Spermatogenesis?
Meiosis from a Spermatogonium where 4 sperms are produced (22+X or 22+Y)
What is Oogenesis?
Meiosis from an Oogonium where 1 Ovum (22+X) and 3 polar bodies are produced
What is special about each sperm and egg?
They are all genetically unique
What happens during fertilisation?
Several sperms surround the ovum but only one penetrates
(pro)Nucleus of sperm enters and fuses with the (pro)Nucleus of the ovum to give a diploid cell called the ZYGOTE
What happens in week 1 of the Pre-embryonic phase?
Zygote is formed; divides to form a blastocyst
Moves through uterine tune, to reach uterine cavity
What is the first cell in the body?
Zygote
What are facts about the zygote?
Diploid (46 chromosomes)
Genetically unique - because it has 23 of mum’s & 23 of dad’s chromosomes
Mitochondria, cell organelles from mum
Cell divides by mitosis forming 2 cells, then 4 cells
What is it called when a solid ball of cells is formed?
Morula
Where are mitochondrial diseases inherited from? Give an example of one
Inherited from the mother
E.g. Leber’s Hereditary Optic Neuropathy -> Blindness
What happens when the number (and size) of cells increase?
Getting nutrition to the central core of cells starts becoming difficult
