Embryogenesis Flashcards
Ampulla
Region of the Fallopian tube where fertilization occurs. It is the widest part of the Fallopian tube.
Acrosomal Apparatus
When the first sperm comes into contact with the oocyte, it releases acrosomal enzymes that enable the head to penetrate the corona radiata and zona pellucida. It forms a tubelike structure known as the acrosomal apparatus that extends to and penetrates the membrane. Its pronucleus then may freely enter the oocyte once meiosis II has come to completion.
Cortical Reaction
release of calcium ions after the penetration of the sperm. The calcium ions depolarize the membrane of the ovum, which serves two purposes: prevents fertilization by multiple sperms. Also increases the metabolic rate of the newly formed zygote.
Fertilization membrane
Depolarizer, impenetrable membrane formed after the cortical reaction
Stages of development of the zygote to embryo?
Zygote, morula, blastula gastrula
Morula
Solid ball of cells after several divisions of the zygote
Blastula
Hollow ball of cells with a fluid filled inner cavity known as the blastocoel
What arises from the trophoblasts?
Chorion and later placenta
What are the two parts of the blastocyst?
Trophoblast and the inner cell mass (ICM).
In what stage is the embryo implanted in the uterine lining?
Blastula
Chorionic villi? What are they and what do they develop from?
Develop from the trophoblasts, and are fingerlike microscopic projections that penetrate the endometrium.
The 3 extraembryonic membranes?
Chorion, Amnion, and Allantois
Allantois?
Extraembryonic membrane that is involved in the fluid exchange between the yolk sac and the embryo.
Umbilical chord forms from what?
From yolk sac and Allantois.
Ectopic pregnancy
If the blastula implants itself outside the uterus. 95% in the Fallopian tube. Not viable, and if not self aborted, will rupture causing hemorrhage.
Name what you see if you move in from the uterine lining towards the embryo
Uterine lining, chorion, chorionic cavity, amnion, amniotic fluid, embryo.
Arcehnteron
Membrane invagination into the blastocoel during the formation of gastrula
Blastocoel
The opening of the archenteron.
Deuterosome
The blastopore develops into the anal opening
Protostome
Blastopore develops into the mouth
Know where the ectoderm, endoderm, and mesoderm are located in gastrula
Just know it!
Integument
Includes hair, nails, epidermis, epithelial of the nose, mouth, nose and lower anal canal.
What does the ectoderm give rise to?
Integument: Hair, nails, epidermis, epithelial of the nose mouth and the lower anal canal
+
Nervous system (including adrenal medulla) and the inner ear
Mesoderm gives rise to…
Musculoskeletal, circulatory systems, and most of the excretory system + gonads, adrenal cortex
+ muscular and connective layers of the respiratory and digestive systems.
What do neural crest cells give rise to?
Peripheral nervous system (including the sensory ganglia, and autonomic ganglia, Schwann cells, and adrenal medulla) +
Specific cell types in other tissues: calcitonin producing cells in thyroid, melanocytes in skin
Spins bifida
Failure of the neural tube to close. All or parts of the spinal cord might be exposed to the outside world
Anencephaly
Brain fails to develop and the skull remains open
What chemical supplement is used to prevent anencephaly and spins bifida?
Folic acid
Pancreas enzymes?
Trypsin, pancreatic lipase, carboxypeptidase A and B
Pancreatic endocrine hormones
Insulin, glucagon, somatostatin
Different types of cell-cell communication? Do you know what each mean?
Autocrine, paracrine, juxtacrine, endocrine.
What are growth factors?
Peptides that induce differentiation and mitosis in certain tissues
Example of reciprocal development? (pax6)
In ectoderm of the head, when optical vesicle touches the ectoderm, it induces the ectoderm to form the lens placode. The lens placode induces the optical vesicle to produce the optic cup. Optic cup induces the lens placode to develop into the lens and the cornea.
Name three common morphogens:
TGF beta (transforming growth factor beta), sonic hedgehog (shh), epidermal growth factor (EGF).
Where does the anterior pituitary gland originate from?where does it travel to?
A segment of the oral ectoderm and migrates to its location below the hypothalamus.
What are the hormones produced by placenta?
Estrogen, progesterone, and hCG (human chorionic gonadotropin).
Name the pathogens that can cross the placental barrier
TORCHES:
Toxoplasma Gondi, Rubella, Cytomegalovirus, Herpes or HIV, Syphilis
What are the shunts in fetus? What organs do they bypass?
Three shunts to bypass lungs and liver.
2 for lungs:
Foramen ovale (connects the right to the left atriums)**One way flap
Ductus arteriosus (connects the flow from the pulmonary artery to aorta)
1 for liver:
Ductus venosus
Connects the umbilical vein to the inferior vena cava.
What happens during the first trimester?
Development of the major organs during the first few weeks
22 days: hear beat begins
Shortly after: eyes, gonads, limbs and liver
By the end of week 5: 10 mm
By the end of week 6: 15mm
Week 7: cartilaginous skeleton hardens into bones
End of week 8: most organs have formed, brain is fairly formed we start to call it a fetus!
End of month 3: 9 cm.
What happens during the second trimester?
Tremendous growth. Fingers and toes elongate Begins movement in the amniotic fluid Face gains human appearance By the end of the sixth months measures 30 to 36 cm.
What happens during the third trimester
Growth and brain development continues during the 7th and 8th months.
Antibodies transported by selective active transport from mother to the fetus. (Highest during the 9th month)
Parturition
Vaginal childbirth
What hormones are involved during parturition?
Oxytocin and prostaglandins.
What are prostaglandins involved in?
Parturition
