Early Human Development Flashcards
Totipotent
Able to generate all cell types, embryonic and extraembryonic (placenta)
Pluripotent
Able to generate cell types from all embryonic germ layers; ectoderm, mesoderm, endoderm
Multipotent
Able to generate all cell types within a germ layer
Ex: multipotent
Bipotential
Able to generate 2 cell types
Ex: neural stem cell (neurons and glia)
Unipotent
Generate only 1 cell type
Committed/cell fate restricted progenitors
Ex: oogonia or spermatogonia
Epithelium
Tightly joined sheet of cell, containing a basement membrane and organized polarity
Non-motile cells
Adherent cells
Closely knit, form a barrier
Mesenchyme
Loosely associated cells, having multiple processes
Usually motile
Ectoderm
Outside layer
An epithelium
Gives rise to skin and the nervous system
Mesoderm
Middle layer
Mesenchym
Gives rise or contributes to most of the internal organs, vasculature, blood, lymphatics
Endoderm
Internal epithelial layer
Gives rise to digestive system (esophagus, stomach, gut) and associated organs (bile duct, gallbladder, parts of pancreas)
Neural crest cells
Multipotent cell type
Arises from the edge of the dorsal neural tube
Migrates extensively to give rise to a wide variety of tissues, including much of the craniofacial skeletal structures, parts of the inner ear, peripheral and sympathetic nerves, Schwann cells, pigment cells
Primordial germ cells
Pluripotent cells set aside during embryology that migrate to populate the gonads during development
In males, give rise to spermatogonia. In females, give rise to oocytes
4 steps in fertilization
- Oocyte penetration
- Acrosomal reaction
- Male and female pronuclei
- Pronuclear fusion
Gastrulation
Formation of the embryonic germ layers
Meiosis
2 step division process by which sperm and eggs are produced
Acrosome
Sac of enzymes that help digest the lipoprotein coat on the egg
Zona pellucida
Lipoprotein coat on the oocyte
4 Phases of fertilization
- Capacitation of the reproductive system
- Acrosome reaction
- Corona and Zona penetration
- Cytoplasm entry
Where does fertilization usually occur?
In the ampulla of the uterine tube
What is the importance of compaction?
It starts the specialization of cells
The inside cells are different from the outside cells
Outside ones become the trophoblast, inner ones become fetus
Associated with the transition from maternal influences on development to the activation of the zygotic genome
What does progesterone do?
Tells the site of implantation to vascularize
Prechordal plate
Beginnings of the system that induces the NS
Where is the amniotic cavity located?
At the pole where the embryo is connected to the mother
Syncytiotrophoblast
So much proliferation that they dont even form cell boundaries Invade into the wall Form sinusoids Multiple nuclei sharing a cytoplasm Gets maternal blood to embryo eventually
Embryoblast splits into 2 layers….
Epiblast (embryo proper)
Hypoblast (or primitive endoderm)
Bilaminar blastoderm/embryonic disc
Remaining epiblast + hypoblast
Decidual cells
When the embryo implants, adjacent cells of the endometrial stroma respond to its presence and progesterone and differentiate into metabolically active SECRETORY CELLS
HCG is secreted by the ___ and does what
Secreted by the trophoblast
It supports the corpus luteum to maintain the supply of progesterone
