3: Embryogenesis and Development Flashcards
SEQ human fertilization
Sperm and egg meet in ampulla of fallopian tube
Acrosomal enqymes penetrate corona radiata and zona pellucida
On contact with egg plasma membrane, acrosomal apparatus injects sperm pronucleus
=> this causes egg acivation. Calcium ions initiate slow block corticol reaction.
Describe cell division during cleavage
Total size constant, but cells divide.
When does zygote become embryo?
After first cleavage
What is a morula?
Solid mass of cells seen in early development
Ectoderm gives rise to what?
Epidermis, hair, nails
Epithelium of nose, mouth, anal canal
Nervous system, including adrenal medulla
Lens of the eye
Mesoderm gives rise to what?
Musculoskeletal system Circulatory system Excretory system Muscle/connective tissue in digestion/respiration Gonads Adrenal cortex
Endoderm gives rise to what?
Epithelia of respiratory system, digestive tract
Pancreas, thyroid, bladder, urinary tracts
SEQ Neurulation
Notochord induces overlaying ectoderm to form neural folds => these fold to form neural tube => tip of each contains neural crest cells, which become PNS and also specific cell types across body, e.g. calcitonin-producing cells in thyroid
What a teratogens?
Substances that interfere with development, e.g. alcohol, some drugs, viruses, bacteria, environment
How does cell specialization start?
Uneven mitosis
Morphogens - promote specialization, provided cell has required competency to respond
What is the difference between totipotent, pluripotent, multipotent cells?
Totipotent – can develop into any kind of cell, including three germ layers and placental structures
Pluripotent – can develop into any of three germ layers
Multipotent – can develop into specific subset of cell types
Define autocrine, paracrine, juxtacrine, endocrine
Crine = signal
Para - next; juxta - adjacent, etc
What is apoptosis?
Programmed cell death via formation of apoptotic cell clebs, which can subsequently be absorbed and digested by neighboring cells. Can be used for sculpting, e.g. removing web between digits
What is the difference between adult hemoglobin and fetal hemoglobin?
Fetal - HbF - has higher affinity for oxygen than HbA – assists transfer into fetal circulatory system
Which direction does blood flow in umbilical arteries/veins?
Umbilical arteries – carry deoxygenated blood from fetus to placenta
Umbilical veins - carry oxygenated blood from placenta to fetus
Which fetal organs are most inactive?
Lungs, liver
What are the three shunts of the fetal circulatory system?
Formen ovale - connects right atrium to left atrium – bypasses lungs
Ductus arteriosus - connects pulmonary artery to aorta – bypasses lungs
Ductus venous - connects umbilical vein to inferior vena cava - bypasses liver
What are the two main cell groups of a blastocyst?
Trophoblast - gives rise to chorion and placenta
Inner cell mass – gives rise to fetus
Define: Chorion Yolk sac Allantois Amnion
Chorion - villi penetrate endometrium
Yolk sac - supports embryo before placenta established
Allantois - involved in early fluid exchange between embryo and yolk sac
Amnion - inside chorion, produces amniotic fluid
