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245 Cards in this Set

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What is Meiosis?
It is a specialized process of cell division that occurs in the gonads and produces male gametes and female gametes.
What is the name of male and female gamete production?
Spermatogenesis and oogenesis.
What are the processes of Oogenesis?
Oogonium
Mitosis: I oocyte
Meiosis I:Polar body+II oocyte
Meiosis II:Polar bodies+ ootid
Ovum
What is the time process of oogenesis?
Before birth- puberty:
Oogonium--> I oocyte(until prophase of meiosis I).

Puberty : I oocyte finishes meiosis I--> II oocyte starts meiosis II until metaphase.
II oocyte arrested in metaphase of meiosis II until fertilization.If no fertiliz occurs then it is ovulated.
Fertilization: II oocyte continues meosis II--> ootid--> ovum.
What is the genetic code of each cell in oogenesis?
Oogonium: 2N
I oocyte: 4N (92 chromo)
II oocyte: 2N
ootid N
ovum N
What is the process of follicle development in ovaries?
Primordial follicle contains the I oocyte (prophase) from before birth till childhood where the ovary remains inactive.
At puberty: Primary follicle contains I oocyte in prophase and leads to Graffian follicle containing II oocyte in metaphase.
What is a Graffian follicle?
It is a large II follicle with a potential for ovulation.
What are the parts of a Graffian follicle?
Theca externa and interna
Follicular cells
Antrum
Zona pellucida
II oocyte
At what gestational monthe does the femal have all her eggs and how many?
At month 5 and with 400,000 eggs rested in prophase when she is born.
What are the processes of spermatogenesis and the cells formed?
Spermatogonium
Mitosis: I spermatocyte
Meiosis I: II spermatocyte
Meiosis II: Spermatids
Sperm cells
What are the cells genetic code in males?
Spermatogonium 2N
I spermatocyte 4N
II spermatocyte 2N
Spermatids N
Sperm cells N
What are the cells present in males from gestation untill puberty?
From week 4 of gestation till puberty: primordial germ cells.
Which cells enter the cycle of spermatogenesis:
Type B spermatogonias.
What happens to male primordil germ cells at Puberty?
Primordial germ cells-->Type A spermatogonia
(stem cells throughout adult life)
Some Type A differentiate into Type B spermatogonias.
How many follicles develop every month since puberty?
8-10
What process do spermatids undergo to form sperm cells?
Spermiogenesis and morphological changes
Where are spermatogonias stored in male genitalia?
The base of the testes where they mature as spermatids.
Where are spermatids located?
At the surface of testes, closer to lumen and they enter the epididymis.
Where are the sperms stored?
In epididymis until ejaculation occurs.
What is the fetal landmark of day 1?
Zygote formation
How long does it take for a sperm to mature and how many mature per day?
It takes 41-72 days
20-40 million sperms mature each day.
How is Male virility measured?
-Sperm count of at least 20 million.
-A minimuom of 4-5 cc of semen per ejaculation = 100 million sperms.
-less than 40% of sperms with abnormal forms. (Natural selection)
-Mimimun 30-60% still motile for 5 mns on a glass slide.
-pH high due to ↑ HCO3.
Events that take place in ovary prior to fertilization?
1.Formation of 8-10 Graffian follicle contains II oocyte+ polar body
2. Rupture of graffian follicle.
3. Expulsion of II oocyte with zona pellucida and cumulus oophorus to fallopian/uterine tube.
4. Formation of primitive corpus luteum from theca cells
What is the purpose of corpus luteum?
It secretes progesterone which prepares and sustains uterine wall for implantation.
What are the events prior to fertilization?
-Sperm capacitation
-Sperm-zona pellucida binding
-Penetration of zona pellucida via acrosome reaction and flagelating tail.
-Sperm-oocyte binding by fusion of sperm head with oocyte plasma membrane.
-Egg activation and cortical reaction where II oocyte finishes meiosis II and alteration of zona pellucida.
- Zona reaction where the zona pellucida hardens and loses sperm receptors.
What is sperm capacitation?
removal of adherent seminal plasma proteins, reorganization of plasma membrane lipids and proteins.
What is the importance of the zona reaction?
It represents the major block to polyspermy.
What are the 6 events that take place during the first week of gestation?
-Fertilization
-Zygote formation
-Cleavage to form blastula-> Morula
-Formation of blastocyst.
-Differentiation of trophoblast.
-Implantation of blastocyst
Where does fertilization occur?
At the distal end of the ampolla (Uterine tube)
What is the result of fertilization?
The formation of a zygote as the male and female pronuclei fuses.
What is the fetal landmark of day 2-3?
2-cell to 16-cells blastulas after 4 cleavage cycles.
Name, # cells and cycles
What is cleavage?
Mitotic divisions of zygote where cells do not grow in size but instead daughter cells becomes half their previous size.
What is the fetal landmark of day 4?
Morula
32 blastomeres
Formation of inner cell mass and outer cell mass
Name, # cells and cell differentaition.
What is the fetal landmark of day 5?
Blastocyst
What are the structural portions pf the blastocyst?
-Inner cell mass or embryoblast
-Blastocyst cavity
-Outer cell mas of trophoblast
What is the event that must take place for implantation to occur?
1. Degeneration of zona pellucida
Part of II oocyte
What will the embryoblast and the trophoblast generate?
Embryoblast--> embryo/fetus
trophoblast--> parts of the placenta
What occurs to the trophoblast of the blastocyst prior to implantation?
It divides into Syncitiotrophoblast and cytotrophoblast
How does implantation occur?
-Embryonic pole of blastocyst.
-Within the the posterior wall of uterus, in the functional layer of the endometrium, during the preogestational phase of the menstrual cycle.
Position of blastocyst
part of uterus
timeframe of menstrual cycle.
What pathologies may occur during the first week?
Ectopic pregnancy.
What is ectopic pregnancy and where can it occur?
Pregnancy outside the uterus occuring in uterine tube and in abdomen.
At the end of lacunar stage of development, what's happening with cytotrophoblast cells and syncytial trophoblast?
Cytotrophoblast cells - form inner layer of placenta
syncytial trophoblast forms outermost placental layer
What is the most common site for an ectopic pregnancy?
Ampulla of uterine tube
what does the placenta do?
It mediates exchange of nutrients and metabolic waste products between cardiovascular system of mom and fetus.
Ectopical tubul pregnancy:
-Cause
-Risk factors (4)
-Clinical signs (6)
-Caused by delayed transport
-Risk factors: endometriosis, PID,tubular pelvic surgery and exposure to DES.
-Clx:Abnormal uterine bleeding, Sudden onset of abdominal pain.
-Last menses 60 days ago
-HCG (+)
- Intraperitoneal blood in culdocentesis.
PID: pelvic inflammatory disease.
DES: diethylstilbestrol
Dx =/ of abd pain is appendicitis
Two components of the placenta
-Decidua Basalis (Maternal)
-Villous chorion (Fetal)
What is the most common site for an ectopic abdominal pregnancy?
Rectouterine pouch (Pouch of Douglas)
Decidua Basalis: What is it?
-Maternal component of the placenta
-A portion of endometrium
What are the 7 events that take place during week 2?
1.Late implantation/ uteroplacental circulation.
2.Formation of bilaminar embryonic disk
3.Formation of amniotic cavity, yolk sac
4.Formation of extraembryonic mesoderm with its two layers
5.Formation of chorionic cavity and definitive yolk sac.
6.Formation of prochordal plate
7.Development of extraembryonic regions associated with trophobast.
Implantation,bilaminar disk,amnios,yolk sac, extraemb mesod,chorion, prochordal plate.
What event starts at the end of the first week and starts the second week?
Late implantation
Villous Chorion: What is it?
-Fetal component of the placenta
-Tertiary chorionic villi
How does late implantation occur?
After differentiation of the trophoblast, the syncitiotrophoblast invades the uterine wall and the cytotrophoblast provides new cells.
Vasa previa: What is it?
Velamentous placenta which crosses the internal os.
What is the placenta, what does it do and when does it begin to develop?
It is an organ formed from blastocyst-derived tissues attached to uterus.
When does the placenta begin to develop?
As soon as blastocyst attaches to endometrium
Velamentous placenta: Cause?
Umbilical vessels abnormally travel through the amniochorionic membrane before reaching the placenta proper.
Maternal Placenta: Afterbirth appearance
15-20 cotyledons imparting a cobblestone appearance. Dark red surface oozing blood (torn maternal vessels).
What is the decidua?
Whta is its function in association to the placenta.
It is the endometrium of pregnancy.
It establishes the limit of the placenta and the invasion of trophoblast.
Give a 7-step summary of the 2nd week of development with regards to the extraembryonic regions?
1. Trophoblast differentiates (cytotrophoblast and syncytiotrophoblast)
2. Lacunae develop
3. syncytiotrophoblast erodes maternal sinusoids and endometrial gland
4. Maternal blood flows into and out of lacunae
5. Uteroplacental circulation established
6. Primary chorionic villi form on external surface of chorionic sac
7. Implantation completed and defect closed
What substance allows the trophoblast to become sticky and attach to the uterine epithelium?
L-selectin.
Fetal placenta: Afterbirth appearance
Chorionic blood vessels. Smooth and shiny as it is covered by amnion.
How is the bilaminar embryonic disk formed?
The inner cell mass or embryoblast becomes two distinct layers, the epiblast and the hypoblast, which are in contact and assume a disc-like shape with the hypoblast facing the blastocystic cavity.
what's the chorion frondosum?
It is the definitive placenta,it consists of:
-villi left over after some disappear from growth of embryo (chorion laeve)
-villi associated with main portion of decidua basalis.
Vasa previa: What is the danger?
If one of the umbilical vessels ruptures during pregnancy, labor, or delivery, the fetus will bleed to death.
What is the structural difference between the epiblast and the hypoblast?
Epiblast: Columnar cells
Hypoblast: Cuboidal cells
Why does the mother not reject the placenta as an allograft?
Syncytiotrophoblast cells lack MHC antigens and decidual cells in the endometrium secrete PGE2 to inhibit T cells.
What takes place after the formation of the bilaminar embryonic disk?
The epiblast develops the amniotic cavity which is filled with amniotic fluid and lined with special cells call amnioblasts
The hypoblast develops the primary yolk sac or exocoelomic cavity.
Coelom = body cavity.
what hormones do trophoblast cells produce?
1. cytotrophoblast start making hCG
2. syncytial trophoblast makes hCG through end of gestation
3. Human placental lactogen (hPL)or chorionic somatomammotropin
4. placental corticotropin releasing hormone
5. ACTH
6. progestins
7. estrogens
What are now the two fluid cavities surrounding the bilaminar disk?
-Yolk sac next to hypoblast
-Amniotic cavity next to epiblast
What do the cells of the primary yolk sac produce?
A layer of loose connective tissue outside the sac: extraembryonic mesoderm. It surrounds the yolk sac, amnion, and bilaminar germ disk.
What happens to the extraembryonic mesoderm after it develops?
Vesicles appear and form an extraembryonic coelom that seperates the extraembryonic mesoderm into two layers.
What are the two layers of the extraembryonic mesoderm? What gets renamed once these layers form?
The outer extraembryonic SOMATIC mesoderm and the inner extraembryonic SPLANCHNIC mesoderm

The extraembryonic coelom gets renamed chorionic cavity.


splanchnic means inside, somatic means outside.
What do the extraembryonic somatic mesoderm and extraembryonic splanchnic mesoderm respectively surround?
Amniotic sac and Yolk sac.
What does the growth of the chorionic cavity cause?
It pinches off the primary yolk sac, creating a smaller secondary yolk sac that beaomes the Gastrointestical tract and its derivatives eventually.
What happens at one end of the bilaminar disk involving attachment?
An area of the hypoblast cells become attached to the overlying epiblast. This is the future site of the mouth (the oropharyngeal membrane) on the top and the other end of the side a similar circle is developed: the cloacal membrane, which is the future site of the anus.
How is the connecting stalk formed and what is its function?
The cytotropho is lined by extraembryonic somatic mesoderm forming the connecting stalk. It suspends the embryo within the chorionic cavity.
What will the connecting stalk become?
umbilIcal cord.
What does syncitio produces?
Human Chorionic gonadotropin (HCG)
What is HCG?
A glycoprotein that stimulates the production of progesterone by the corpus luteum and maintain it functional.
Does production of hCG drop when corpus luteum dies?
no; it is constantly produced by syncytiotrophoblast.
When can hCG be assayed in maternal blood and urine?
Blood: 8 -11 days
Urine: 10 days
What is the amount of HCG detectable in blood serum diagnose for pregnancy?
Anything above 25 mIU/ml (25 IU/L) is positive for pregnancy.
How does HCG normally fluctuate during pregnancy?
Levels double every 30.9 hours until it reaches 6500 mIU/ml (6,500 IU/L) the eighth week after LMP.
HCG decreases slightly between the 12th and 16th week post LMP, and then remains constant until birth.
LMP: last menstrual period
What are HCG values:
at 7,14,21,28,35-42 days
17,25 weeks and postpartum?
conception LMP IU/L)
7 d 3 w 0 - 5
14 d 28 d 3 - 426
21 d 35 d 18-7,340
28 d 42 d 1080-56,500
35/42 d 49/56 d 7,650 229000
17/24 w 2 trim 4060- 65,400
25w/term 3 trim 3640-117,000

After several days postpartum: nonpregnant <5
What can low levels of HCG be attributed to?
-Spontaneous abortion
- Ectopic pregnancy
What can high levels of HCG be attributed to?
-Multiple pregnancy
-Hydatidiform mole
-Gestational trophoblastic diseases.
What is Hydatidiform mole?
Tumor of placental trophoblastic tissue.
How does it occur?
Blighted blastocyst or dead embryo is followed by hyperplastic proliferation of the trophoblast within the uterine wall.
What are the two types?
-Complete mole: fertilization of ovum that lost all its chromosomal material
-Partial mole: fertilization of ovum ,that has not lost all its chromosomal material, by 2 sperms: 23,X; 23,Y)
What are the characteristics of the complete mole?
-All chromosomal material derive from sperm
-90 % time, molar karyotype is 46 XX and 10 % of the time 46,XXY
-No embryo development
What are the characteristics of the partial mole?
- Triploid cell
- Molar karyotype is 69,XXY (23X maternal; 23X paternal; 23Y paternal)
- Embryo may develop in a few weeks.
What are the clinical signs of Hydat mole?
What are the clinical signs of Hydat mole?
-Preeclampsia during 1st trimester (HTA, edema, proteinuria)
-High HCG (> 100,000 mIU/ml)
-Enlarged uterus with bleeding
-Vaginal bleeding
- Passage of edematous, grapelike soft tissue.
What are the pathological findings?
-Edematous chorionic villi
-Trophoblast proliferation:
Marked in complete mole and focal in partial mole
-Fetal tissue in partial mole
What is the Dx?
Ultrasound
What is the Tx?
-Endometrial curettage
-Follow HCG levels
What can be the evolution of hydatidiform mole?
10 % chances of invasive mole (into myometrium of uterine wall)
2-5 % develop gestational trophoblastic neoplasia in case of complete mole.
What is GTN?
Gestational trophoblastic neoplasia or choriocarcinoma.
It si a malignant tumor of the trophoblast.
What are the risk factors?
-Normal pregnancy
-Abortion
-Hydatidiform mole
What are the pathological findings?
-Necrotic and hemorrhagic mass
-Proliferation of cytotrophoblasts and syncitiotrophoblasts.
What is the Dx?
Suspicion in case of High HCG
What can be the evolution?
Hematogenous spread to lungs,brain,liver and testes
What is the Tx?
It responds to chemo.
What is the Fetal landmark, Within week 2?
RULE OF 2S:
Bilaminar disk:(epiblast,hypoblast)
2 cavities:(amniotic cavity,yolk sac)
2 placental components:(cyto/syncytiotrophoblast)
RULE OF 2S
What is the fetal landmark, Within week 3?
1.Gastrulation:(Ectoderm, Mesoderm, Endoderm)
2.New structures(Primitive streak,notochord,neural plate)
RULE OF 3S
What are the 2 events that take place during gastrulation?
1. Primitive streak formation
2.Germ layers formation
How is the primitive streak formed?
The primitive streak develops from thickened line at caudal end of disk, within the epiblast. The primitive node forms more cranially, both move and elongate towards cranial end of disk, depress and become the primitive groove and pit.
How are the germ layers formed and what are they named?
The epiblast cells migrate through the groove and pit ventrally, some of those cells displace the existing hypoblast and create a new hypoblast layer, the embryonic endoderm. Other cells move inbetween the epiblast and hypoblast creating the intraembryonic mesoderm. The cells staying in the epiblast are called the embryonic ectoderm.
what happens 21 days after ovulation?
fetal heart begins to beat and moves blood through placenta.
Where in the trilaminar disc is there only two layers?
What are they?
1.At the oropharyngeal membrane cranial or anterior (future mouth= prechordal plate)
2.At the cloacal membrane caudal or posterior (future anus).
They are pecifically ectoderm and endoderm.
What happens at the margins of the embryonic disc ?
The intraembryonic and extraembryonic mesoderm become continuous.
What does the mesoderm that migrates cranially of the prechordal plate become?
the cardiogenic area.
How is the notochord formed?
Cranial migration of the mesoderm from the primitive node.
What will the notochord induce?
They will induce the overlying ectoderm to thicken and form the neural plate= neuroectoderm.
What process takes place then?
Neurulation
What is neurulation?
It is the events that lead to formation of CNS:
1.the plate folds into the neural folds.
2.the folds close to form the neural tube starting in the middle and proceeding out toward head and tail forming anterior and posterior neuropores.
1. Cranial neuropore closes earlier than caudal neuropore.
3.The central nervous system (CNS) arises.
When does neurulation start and finish?
It commences in the third week and is completed by the end of the fourth week.
What is successful neurulation dependent upon?
Adequate levels of folate.
Towards the end of the 3rd week, what causes the primitive streak to shrink and eventually disintegrate?
Cranial pole development.
What are the germ layers differentiation?
Ectoderm: Neuroectoderm and Neural crest cells.
Mesoderm: Paraxial mesoderm, intermediate mesoderm and lateral mesoderm.
Ectoderm.
What does the paraxial mesoderm , intermediate mesoderm and lateral mesoderm give rise to?
-somites (blocks of tissue).
-urogenital system (Gonad and Kidney).
-Intraembryonic somatic and splanchnic.
What do the Intraembryonic somatic and splanchnic lateral mesoderm give rise to?
-somatic: body wall
-splanchnic: wall of gut
What do the somites give rise to?
1. Dermatome (dermis of skin)
2. Myotome (muscles)
3. Sclerotome (bone, cartilage)
What is the dermomyotome?
Part of somite that gives rise to skeletal muscle and connective tissue.
What happens as neural folds are closing?
1.Lateral and longitudinal folding of Trilaminar disk
--> a cylindrical body form.
2.The 2' yolk sac gets pinched in from all sides and gets smaller--> the umbilical area.
3.Amniotic cavity growth--> lateral folding --> gut tube that runs from mouth to anus and internal body cavities.
How are the internal body cavities formed in the embryo?
The vesicles in the lateral plate mesoderm converge, dividing it into two layers, one lining the inside of the future body wall (parietal/somatic layer) and one the outside of the yolk sac (splanchnic/visceral layer).
The meeting of the amniotic cavity ends creates the internal body cavity called the intraembryonic coelom.
What will the intraembryonic coelom eventually become (week 8)?
1.pleural cavity, 2.pericardial cavity
3.peritoneal cavity
What is the period of maximal sensitivity to abnormal development (which weeks)?
Weeks 3-8
Skin ectoderm derivatives.
1. EPIDERMIS (hair, nails, glands)
2. Ant. pituitary gland or adenohypiphysis
3. Lens of eye
4.Cochlear ducts and semicircular ducts
5.Glands: sweat, salivary, parotis and mammary
6. Epithelial lining of lower anal canal.
6. Enamel of teeth
Neuroectoderm derivatives
1. Neurons of brain and spinal cord
2.Astrocyres and oligodendrocytes
3.Neurohypophysis
4. Retina
Neural crest derivatives
1. Pigment cells, schwann cells and meninges: PIA nad ARACHNOID mater.
2. Sensory and autonomic ganglia.
3. Odontoblasts
4.Pharyngeal arch cartilage
5.Adrenal MEDULLA
6.Prafollicullar cells
7. Aorticopulmonary septum and endocardial cushions.
Mesoderm derivatives
1.Connective tissue, cartilage, bone,DERMIS of skin
2.striated and smooth muscle
3.heart, Kidneys,spleen and adrenal CORTEX
4.blood, lymphatic vessels, 5.ovaries, testes, genital ducts
5.serous membranes (pericardial, pleural, peritoneal.
6. DURA MATER
7. Muscles of tongue (occipital somites)
8 Extraocular muscles (preoptic somites)
Notochord derivatives
Nucleus pulposus.
Endoderm derivatives
1.Epithelial lining of GI and respiratory tracts.
2.Epithelial lining of urinary bladder, most of urethra,tympanic cavity, tympanic antrum and auditory tube.
3.Parenchyma of thyroid and parathyroid, tonsils, liver, pancreas, thymus,sublingual and submandibular glands.
Derived from what germ cell layer: Cornea
Ectoderm:(Anterior epithelium), Mesoderm:(Substantia propria and endothelium)
Derived from what germ cell layer: Eye
Ectoderm:(lens, anterior epithelium of cornea),Neuroectoderm:(iris, dilatory/sphincter pupillae muscles),Mesoderm:(extraocular muscles, sclera, substantia propria of cornea, corneal endothelium, ciliary muscle of eye, choroid)
Derived from what germ cell layer: Utricle, mammary and parotid gland.
Ectoderm
Derived from what germ cell layer: Acinar and islet cells of pancreas sublingual and submandibular gland.
Endoderm
Derived from what germ cell layer: Ameloblasts (columnar epithelium of enamel inner layer)
Skin Ectoderm
Derived from what germ cell layer: Bones of neurocranium
Neurocrest
Derived from what germ cell layer: Choroid plexus cells
Neuroectoderm
Derived from what germ cell layer: Chromaffin cells of the adrenal medulla
Neural crest
Derived from what germ cell layer: Ciliary body
Neuroectoderm
Derived from what germ cell layer: CN I
Skin Ectoderm
Derived from what germ cell layer: CN II
Neuroectoderm
Derived from what germ cell layer: CNS neurons
Neuroectoderm
Derived from what germ cell layer: Ependymocytes
Neuroectoderm
Derived from what germ cell layer: Epithelial lining of distal part of male urethra
Ectoderm
Derived from what germ cell layer: Epithelial lining of female urethra
Endoderm
Derived from what germ cell layer: Epithelial lining of GI tract
Endoderm (except lower anal canal: Ectoderm)
Derived from what germ cell layer: Epithelial reticular cells off thymus
Endoderm
Derived from what germ cell layer: Hepatocytes
Endoderm
Derived from what germ cell layer: Iris
Neuroectoderm
Derived from what germ cell layer: Kupffer cells
Mesoderm
Derived from what germ cell layer: Laryngeal cartilages
Mesoderm
Derived from what germ cell layer: Pharyngeal arch cartilages
Neural crest
Derived from what germ cell layer: Melanocytes
Neural crest
Derived from what germ cell layer: Meninges
Neural crest:(Pia and arachnoid),Mesoderm:(Dura)
Derived from what germ cell layer: Microglia
Mesoderm
Derived from what germ cell layer: Olfactory placodes
Ectoderm
Derived from what germ cell layer: Optic chiasm and optic tract
Neuroectoderm
Derived from what germ cell layer: Oxyphil cells of parathyroid
Endoderm
Derived from what germ cell layer: Pharyngeal arch muscles
Mesoderm
Derived from what germ cell layer: Pineal gland
Neuroectoderm
Derived from what germ cell layer: Pituitary gland
Ectoderm:(Anterior pituitary),Neuroectoderm:(Posterior pituitary)
Derived from what germ cell layer: Salivary gland acini
Ectoderm:(Parotid),Endoderm:(Submandibular,Sublingual)
Derived from what germ cell layer: Sclera of eye
Mesoderm
Derived from what germ cell layer: Sebaceous glands
Ectoderm
Derived from what germ cell layer: Sphincter pupilae muscles
Neuroectoderm
Derived from what germ cell layer: Spiral ganglion of CN VIII
Ectoderm
Derived from what germ cell layer: Substantia propria of cornea
Mesoderm
Derived from what germ cell layer: Sweat glands
Ectoderm
Derived from what germ cell layer: Tanycytes
Neuroectoderm
Derived from what germ cell layer: Tooth
Ectoderm:(Ameloblast),Neural Crest:(Odontoblast)
Derived from what germ cell layer: Vestibular ganglion of CN VIII
Ectoderm
Fetal landmark, Week 4
Heart begins to beat (4 chambers on week 4), Upper and lower limb buds begin to form
Fetal landmark, Week 8
Fetal movement, fetus looks like a baby
Fetal landmark, Week 10
Genitalia have male/female characteristics
Most common congenital malformations
Heart defects, Hypospadias, Cleft lip, Congenital hip dislocation, Spina bifida, Anencephaly, Pyloric stenosis
Monozygotic twins: # of placentas, amniotic sacs and chorions
placenta, 2 amniotic sacs, 1 chorion (or 2 placentas, 2 amniotic sacs, 2 chorions)
Dizygotic twins: # of placentas, amniotic sacs and chorions
2 placentas, 2 amniotic sacs, 2 chorions
Contents of the umbilical cord
umbilical arteries (deoxy from fetal iliacs), 1 umbilical vein (oxy to fetus), Allantoic duct (functions like fetal urethra) all floating in Wharton's jelly and surrounded by amniotic epithelium
How many umbilical arteries are normally present and what happens if the wrong number is present?
2 (1 umbilical artery is associated with congenital and chromosomal abnormalities)
What are oncofetal antigens?
Cell surface antigens that normally only appear on embryonic cells.
What is Carcinoembryonic antigen (CEA) and what is it associated with?
-Oncofetal antigen
-Associated with Colorectal carcinoma
What is alpha-Fetoprotein and what is it associated with?
-Oncofetal antigen
-associated with hepatoma and germ cell tumors
What is the Hox complex?
-Family of genes which encode transcription factors which control segmentation of the human embryo in a craniocaudal direction.
Sacrococcygeal teratoma: What does it arise from? What does it contains?
Remnants of the primitive streak.
Various types of tissue: bone,nerve,hair...
Sacrococcygeal teratoma: What population?
Female infants
Sacrococcygeal teratoma: Timetable and therapy
-Malignant during infancy
-Must be removed by 6 months of age
Chordoma: What does it arise from?
Remnants of the notochord
Chordoma: Where on the body is it found?
-Intracranially
-Sacral region
Chordoma: What population?
Men over age 50
Chordoma: Benign or malignant
Either
What is another name for caudal dysplasia?
Sirenomelia
Caudal Dysplasia: How does it manifest?
constellation of syndromes ranging from minor lesions of the lower vertebrae to complete fusion of the lower limbs
Caudal dysplasia: What causes it?
Abnormal gastrulation (disturbance of mesoderm migration)
Why does the mother not reject the placenta as an allograft?
Syncytiotrophoblast cells lack MHC antigens and decidual cells in the endometrium secrete PGE2 to inhibit T cells.
Where do germ cells originate?
ectodermal cells of the inner cell mass of the embryo
What is the pronephros?
Most primative form of kidney found in developing mammalian embryos that degenerates and gives way to the mesonehpros
What does the mesonephric duct become?
Wolfian duct in males
What does the pramesonephric duct become?
Mullerian duct in females
What does the metenephros become?
Adult kidney and urinary ducts
What determines sex in humans?
Presence of a Y chromosome
What region codes for testicular development in humans?
Short arm of the Y chromosome
What is SRY?
Gene that causes embryo to be male; produces anti-Mullerian hormone; codes for DNA binding protein
What does SRY cause the genital ridge to differentiate to?
Sertoli cells
What do Sertoli cells secrete?
anti-Mullerian hormone
What 2 things does AMH cause?
differentiation of Leydig cells
Causes Mullerian ducts to regress
What do Leydig cells do?
Secrete testosterone
What do the Wolffian ducts become?
vas efferentia, epididymis, vas deferens and seminal vesicles
What does lack of testosterone cause?
Regression of Wollfian ducts
How do the testis get into the scrotum?
The gubernaculum expands and then regresses, pulling the testes through the inguinal ring
What does a 5-alpha reductase deficiency cause in males?
testosterone cannot be made into DHT
What characteristics do males of 5a reductase deficiency have?
testis, AMH, some Wolfian ducts, pseudovagina, and female external genetalia
What may happen to males with a 5a reductase deficiency?
At puberty they may differentiate into a phenotypic male
what is wrong with XY individuals that have testicular feminization?
no androgen receptors
What to testicular feminization individuals have internally?
testis w/ AMH

no Wolffian or Mullerian duct development
What do testicular feminizaiton individuals have for external anatomy?
female genetalia
What will happen if germ cells fail to migrate from the yolk sak to the genital ridge?
If germ cells fail to migrate from the yolk sak to the genital ridge, GONADAL AGENESIS
What are the 3 major systems in forming internal and external genitalia?
Wolffian (mesonephric) ducts, Müllerian (paramesonephric) ducs, and Urogenital sinus.
What system is involved in vagina formation?
Upper 4/5 Müllerian
Lower 1/5 Urogenital sinus
What system is involved in Male internal genitalia formation?
Wolffian
What system is involved in External genitalia formation?
Urogenital sinus: External genetalia (male & female)
What system is involved in internal female genitalia?
Müllerian
What sytem is involved in urogenital track?
Wolffian
What do Sertoli cells produce during sexual differentiation that is important to development?
Sertoli cells: produce MIF (Müllerian inhibiting factor --> no upper 4/5th of vagina, no internal female genetalia
What do Leydig cells produce during sexual differentiation that is important to development?
Testosterone: which maintains Wolffian ducts and virilizes external genetalia
If there is no SRY, what 2 things will happen?
No SRY (1) --> no MIF --> Müllarian ducts maintained… (2) No Testosterone --> Wolffian duct regress --> no external virilization
What does Testosterone do in sexual differentiation?
Testosterone: maintains Wolffian ducts (external male genetalia) and virilizes external genetalia
Give the time line of beginning of ovary fomation, ooctyes, to pirmordial follicles.
8-9 weeks: ovary fomation… 11-12 weeks: discernable ooctyes… 14th week: pirmordial follicles.
In Males: what do Leydig cells produce and what are the effects of this product on the internal genitalia development?
Leydig --> T --> (1) Wolffian ducts convert to vasa deferentia, semianl vessicles and epididymis. (2) and separate into kidneys and ureters.
What remnant is left when MIF causes the Müllerian ducts to regress in males?
What remnant is left when MIF causes the Müllerian ducts to regress? PROSTATIC UTRICAL
In females, what does a lack of MIF cause?
No MIF: 2 Müllerian ducts contact in midline, fuse and canalize--> form uterus, tubes and upper 4/5 of the vagina
MATCH THESE FEMALE UROGENIC SINUS STRUCTURES: clitoris, labial minor, lower 1/5 of vagina, labial majora, urethra… WITH THESE MALE UROGENIC STRUCTURES: urethra, glans penis, penile shaft, scrotum, labioscrotal fusion.
FEMALE=MALE: urethra=urethra…Clitoris=Glans penis… Labial minora=Penile shaft… Labial majora=Scrotum… Lower 1/5 of Vagina=Labioscrotal fusion
What is androgen insensitivity?
Androgen Insensitivity: Inactive Androgen-® (not reactive to T or DHT)
Do people with androgen insenstivity have normal SRY, MIF and T?
Yes, 46 xy --> SRY… and Gonads are testes --> MIF & T
Given that people with adrogen insensitivity produce SRY, MIF and T, what ducts remain?
With SRY (TDH) --> Gonads (testis) --> MIF and T... (a) Leydig cells --> T --> No T-® --> no maintenance of Wolfian Ducts --> regression of Wolffian ducts ... (b) Sertoli cells --> MIF (is independent of T-®) --> regression of Müllerian ducts
Given that people with adrogen insensitivity can still produce SRY and MIF --> thus they don't make Müllerian ducts, what are the ramification of no Müllerian ducts?
With SRY (TDH) --> Gonads (testis) --> MIF: (b) Sertoli cells --> MIF (is independent of T-®) --> regression of Müllerian ducts --> no uterus, no tubes, no upper 4/5 of vagina...
Given that people with adrogen insensitivity can still produce SRY but they don't make T --> they can't maintain Wolffian ducts, what are the ramification of no Wolffian ducts?
With SRY (TDH) --> Gonads (testis) --> MIF and T... (a) Leydig cells --> T --> No T-® --> no maintenance of Wolfian Ducts --> regression of Wolffian ducts --> no virilization of external genitalia…
Given that people with adrogen insensitivity can still produce SRY but they don't make T --> they can't maintain Wolffian ducts, what are the ramification of no Wolffian ducts... ALSO, given that people with adrogen insensitivity can still produce SRY and MIF --> thus they don't make Müllerian ducts, what are the ramification of no Müllerian ducts... AND given that androgen insensitive people still have a functional UROGENITAL SINUS
With SRY (TDH) --> Gonads (testis) --> MIF and T... (a) Leydig cells --> T --> No T-® --> no maintenance of Wolfian Ducts --> regression of Wolffian ducts --> no virilization of external genitalia… (b) Sertoli cells --> MIF (is independent of T-®) --> regression of Müllerian ducts (+ prostatic utricle) --> no uterus, no tubes, no upper 4/5 of vagina... (NOTE: default structures formed by the UROGENITAL SINUS are female --> THUS, external genitalia (no virilization), lower 1/5 of vagina
What are the characteristic of an Androgen Insensitive person?
Regression of Müllerian (MIF present) and Regression of Wolffian ducts (No T-® sensitivity no maintenance), No virilization (noWD) of default external genitalia (+ US), No upper 4/5 of vagina (no MD), no uterus (no MD), no tubes, with lower 1/5 of vagina-small vagina (+ US) ... Also Scan pubic hair and large breast (No T-®)...
Why is it that Androgen Insensitivity and 5∂ Reductase deficiency have different characteristics?
Both are 46 xy: With 5∂ Reductase there is T it's just not convereted to the more potent DHT… Both Androgen Insensitivity and 5∂ Reductase deficiency start off very similar (SRY --> MIF + T), Wolffian ducts develop - yet without DHT, their development is insufficient to produce early virilization of external genitalia… HOWEVER, in puberty T overrides androgen receptor to start virilization ==> PENIS AT 13
In Turner syndrome what is the genetic sex? what is the effect on the Müllerian ducts and the Wolffian ducts?
Turner's Syndrome: 45X… (2) No Wolffian ducts… but Müllerian ducts develop.
Since Turner's Syndrome has 45,X, and Müllerian duct develop, but Wolffian ducts regress, what are the sexual characteristic?
Turner's Syndrome: US: lower 1/5th of vagina, with default female external genetial… MD: upper 4/5th of vagina… NO WD: NO virilization of external genetalia… with scant pubic hair and small breast and normal vagina, normla uterus, and streak ovaries.
What are the two sex reversed syndromes? And what causes the problem?
46 XY Female: deletions on SRY: no MIF no T (similar to 5∂ reductase deficiency)… 46 XX Male: trasnslocation of SRY to X: MIF and T (masculinization of external genetalia, no upper 4/5th of Vagina)