Principles of embryology Flashcards
How long does in utero human development last?
37-40 weeks (3 trimesters)
what are the 6 phases of embryogenesis?
- Gametogenesis
- Fertilisation
- cleavage
- Gastrulation
- Formation of a body plan
- organogenesis
What occurs during gametogenesis and which two cellular processes are involved in this?
The formation of a gamete occurs.
Gametogenesis consists of mitosis and meiosis
What are the types of gametogenesis called for the different genders
spermatogenesis- male
oogenesis- female
when does oogenesis start and end?
by weeks, 28-30, primary oocytes begin meiosis but arrest in prophase until puberty
When does spermatogenesis start and end?
Occurs at puberty and continues throughout life
What is fertilisation?
The fusion of the sperm and the oocyte to form a zygote
When is the embryonic period of development?
Weeks 3-8
What occurs during the cleavage stage?
This is a period of rapid mitotic cell division with no increase in size
What is formed during the cleavage stage
Formation of morula then a blastocyst
What is formed during gastrulation?
Formation of germ layers - ectoderm, mesoderm and endoderm
What develops from the ectoderm?
Hair, skin, nails, nervous tissue
What develops from the mesoderm?
Skeletal muscle, smooth muscle, bone, cartilage, joints, connective tissue etc
What develops from the endoderm?
Inner linings of the organs in the digestive and respiratory systems
How is the body plan formed?
embryonic folding
