Card Set Information
OBIO Exam III
At what week is the embryo become the fetus?
During the first two weeks of development the zygote is not susceptible to teratogens
What is the most common birth defect?
Cleft lip and palate
Male sperm begin forming when?
At puberty due to surge of LH and FSH
In Meiosis how many cross over events occur?
30-40, 1-2 per chromosome
When do homologous pairs align in meisosis?
During metaphase I
When do primordial germs cells form in embryogenesis?
During week 2, in epiblast and hypoblast
4-6 weeks in polar body wall at gential ridge form the gonad
How long is the process for male gametes?
What happens at puberty in males to start spermatogenesis?
Leydig Cells are exposed to LH and in turn produce testosterone
How early is egg formation in femals?
Week 6 of embryo
Describe oogenesis pre-puberty?
mitosis produces many oogonium
primary oocyte fetally undergo meiosis I and arrest at prophase
female born with 400K-600K primary oocytes
Describe oogenesis puberty?
a primary oocytew undergoes oogenesis
LH inc and leads to finish meiosis I, forming secondary oocyte and polar body
then enters meiosis II and stops at metaphase II until fertilization
Why does a polar body form in oogenesis?
The cytoplasm from the polar body if robbed by the secondary oocyte to increase it's lifespan until implantation which does not occur for 2 weeks
What does the follicle produces?
Estrogen and progesterone
describe folliculogensis pre-puberty?
start as squamous cells
describe folliculogeneiss at puberty?
FSH stimulates 5-15 of primordial follicle to re-enter folliculogensis
cells fatten and become cuboidal and begin produicing estrogen
Zona Pellucida forms (glycoprotein layer) important until implantantion, not needed when implanting (can impede)
follicular cells secrete lots of lfuid to fill antrum
What cells produce estrogen?
What cells produce progesterone?
What are the three phases of female reproductive cycle?
Menstrual or uterine
What hormone dominates luteal phase?
How does birth control work?
High P4 and High estrogen causes LH to stay low.
What is the most common numerical chromosome abnormality?
Trisomy caused by non-disjunction
Two microdeletion syndromes, name and describe?
What is the embryo termed from 1-2 weeks?
Morula (16 cells) or blastocyst
What is the embryo termed week 2?
Embryo, bilaminar disk
What is capacitation?
Sperm undergo breakdown of glycoprotein coat by uterine secretions exposing receptors that allow to penetrate the egg
What is the path of the egg from ovary to uterus?
Ovary to abdominal cavity to infundibulum to ampulla to isthmus then to uterus
Union of egg and sperm phases?
1. Corona Radiata
: penetration by capacitated sperm
2. Zona Pellucida
: penetrated by acromsomal rxn after binding of proteins sperm-egg
3. Zona Reaction
: enzymes release in egg hardens to prevent any other sperm, meisosis II finishes
Zygote forms after sperm fertilizes egg and meiosis II finishes in egg
What is the function of zona pelucida after fertilization?
Limits growth of embryo allowing cells to be more condensed and have different contacts
What cells form the placenta?
The trophblasts or periphery cells
End of second week the embryoblast has what two layers?
Epiblast (dorsal) and hypoblast (ventral)
What does the sphlanchnopleuric mesoderm give rise to?
connective tissue that surrounds the umbilical cord
What is the synctiotrophoblast responsible for?
Lose cell membrane releasing enzymes that erode the uterus and produce HCG which allows P4 to continue to be produced
When is uteroplacenta circulation established for nutrition of embryo?
What does GIFT stand for?
Gamete into Fallopian Tube
What is a molar pregnancy?
growth of placental material, secretes HcG, 1% of pregnancies, all trophoblastic cells
5% of moles cause carcinoma
When does the primitive streak form and the embryo is termed going through gastrulation?
Beginning week 3
At what areas of the embryo will you not find any mesoderm?
Buccopharyngeal and cloacal membranes, ecto and endo derms approximate each other
When does neuralation begin?
What do neural crest cells differentiate into?
sensory ganglia, ANS, and glial cells
What is dextro cardia?
Gastrulation defect, heart apex lies on the right side of the body
What is situs inversus?
Gastrulation defect can be complete or incomplete, organs are not where they should be, reveresed
When the primitive streak does not regress at 4th week what can happen?
sacrococcygeal terotoma may form, benign tumor
When are organs done developing?
by week 8, now fetal period where everything rapidly grows
What is lanugo?
fines hairs weeks 17-20 that cover fetus, degenerate before birth
What is vernix caseosa?
waxy cheese sebaceous fluid covering fetus weeks 17-20, antibacterial
When do the testes decend from the posterior abdominal wall?
When is surfactant begin to be produced?
Weeks 21-25, by type II cells, sufficient surfactant is present week 28
Blood formation and weeks 9-12?
Shifts from liver to spleen
Blood formation and weeks 26-29?
shift from spleen to the bone marrow
What are ways to monitor fetal development?
: noticeable defects
2. Maternal serum screens
: downs syndrome
4. Chorionic villi sampling
Weeks 30-35, significant changes?
pupillary light reflex,
testes reach scrotum, mine were at 2 weeks!
Breathing and weeks 26-29?
can occur under control of CNS
When is the blink reflex present?
When do bones begin to ossify?