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MCB 135E Exam I Review. Jason Lowry Fall 2005. General Information. Exam I – Wednesday 10/5/04 In-class exam (50 minutes, 100 points) You will need a pencil and a pen If you write short answers in pencil, they are not eligible for regrade We will provide a scantron

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mcb 135e exam i review

MCB 135E Exam I Review

Jason Lowry

Fall 2005

general information
General Information
  • Exam I – Wednesday 10/5/04
    • In-class exam (50 minutes, 100 points)
    • You will need a pencil and a pen
    • If you write short answers in pencil, they are not eligible for regrade
    • We will provide a scantron
    • You will need to place everything except pen/pencil at the front of room or in the aisle (NOT UNDER THE CHAIR)
    • The exam will not begin until everyone has complied
general information3
General Information
  • Exam I
    • Material for exam will cover everything through the lecture on Monday (10/3/05)
    • Exam breakdown
    • Exam questions are based on lecture material (not website nor discussion)
review material
Review Material
  • Reproductive Systems
  • Fertilization and Implantation
  • Embryonic Development
  • The placenta and hormones of pregnancy
  • Nervous System Development
  • Sexual Differentiation
  • Metabolism and Growth
  • Spermatogenesis
    • What is it
    • Where does it occur
    • What are the hormones involved
    • What is the progression of sperm maturation
    • What are the major characteristics of sperm
  • Formation of Spermatozoa (Sperm)
  • Occurs in seminiferous tubules
  • Involves two distinct maturational processes
    • Spermatocytogenesis
      • 1st Stage of sperm formation
      • Spermatogonium  Spermatids
      • Involves mitosis(46 Chromosomes) initially and then meiosis (23 Chromosomes)
    • Spermiogenesis
      • Spermatids  Spermatozoa
  • Oogenesis
    • What is the function of the ovaries
    • What is the process of oogenesis
    • What are the hormones involved
    • How are these hormones regulated
the ovaries
The Ovaries
  • Gamete producers
  • 3 cm long solid mass of cells
  • Suspended in the abdomen by ligaments and mesenteries
  • Oocytes found on outside surface of ovaries
  • Primary Oocytes form at 3 months during fetal development
  • 2 million primary oocytes by birth in prophase of first meiotic division
  • Maturation
    • Increased size and Meiosis
  • First meiotic division resumes a few hrs before ovulation due to LH Surge
  • Second meiosis after fertilization
  • Division produces unequal mass of cells most food goes to ovum and none to polar body.
  • All polar bodies die eventually.
  • Oocyte+specialized cells=follicle: Nourish ovum and secrete estrogens
  • Mature follicle bursts releasing ovum.
  • Many follicles enlarge but only one bursts.
gamete comparison


Small Size

Elongated Shape

Millions in #

Vigorous Motility

No protecting envelope

Minimal Cytoplasm

Lacks yolk

Centrosome Retained

Mitochondria in body

Golgi Apparatus in acrosome

Nucleus condensed in head




Large size

Spheroidal shape

Few in #

Lack motility

Egg envelopes for protection

Bulky Cytoplasm

Little Yolk

Centrosome Disappears

Diffuse mitochondria

Diffuse golgi apparatus

Open structured nucleus


Gamete Comparison
fertilization and implantation
Fertilization and Implantation
  • Fertilization
    • Sperm Morphology
    • Organization of ovum after ovulation
    • Role of ovum in fertilization
    • Role of sperm in fertilization
    • Stages of fertilization
    • What is capacitation, acrosomal reaction, zona pelucida
  • Implantation
    • Pre-implantation events
    • Act of implantation
  • Role of Ovum
    • Contribute the maternal complement of genes
    • Reject all sperms but one
    • Provide food reserve until the embryo begins to feed upon exogenous material
  • Role of Sperm
    • Reach and penetrate the egg
    • Activate the egg to nuclear and cytoplasmic division necessary to embryonic development
    • Contribute the paternal complement of genes
stages of fertilization
Stages of Fertilization
  • Penetration
    • Random contact between sperm and egg
    • Sperm propel past corona cells and attach to zona pelucida
    • One sperm-One Egg
  • Activation
    • Completion of Meiosis of ovum – forms female pronucleus
    • Sperm Changes – Sperm travels toward center of egg, head swells, becomes male pronucleus
    • Rearrangement in egg – biochemical changes necessary prior to nuclear fusion
  • Nuclear Fusion
    • Union of two pronuclei
    • Loss of nuclear envelope, contribution of chromosomes to first mitotic cleavage
uterine preparation
Uterine Preparation
  • Estrogen
    • Involved in proliferation of uterus (hypertrophy)
    • 3-5 Days post-ovulation E dominates and is thought to play a role in transport of ovum
  • Progesterone
    • Increased Vascularization (hypervascularization)
    • 5-7 days post-ovulation, P increases and counters the effect of E thus relaxing uterine contractions
  • Days 1-8
    • Fertilized egg begins to divide by cleavage into smaller blastomeres
    • Blastomere increase follows a double synchronous sequence initially, but later becomes asynchronous
    • Later stage cleavage forms a ball of cells or morula
    • Fluid begins accumulating in morula and a conversion occurs to the blastula (blastocyst)
    • Blastocyst attaches to uterine stroma
    • Outer layer of cells begin to proliferate and invade stroma of uterus
  • Days 8-16
    • Blastocyst lodged in uterine stroma
    • Trophoblast (outer cells) invades uterine stroma and begins to form placenta
    • Blastocele becomes chorionic cavity
    • Inner cell mass begins to proliferate and form germ disc and primitive entoderm
    • Complex sequence of chemical and physical interactions occur between ovum and mother
      • Only about 50% of fertilized eggs successfully implant
embryonal development
Embryonal Development
  • Germ Layer Theory
  • Gastrulation
  • Tissues generated
Germ Layer Theory
  • Embryo’s Method of sorting out its parts
    • Ectoderm – Outer covering of embryo
    • Entoderm (Endoderm) – Lies under the ectoderm and forms lining of the primitive gut cavity
    • Mesoderm – Develops between ectoderm and entoderm
  • Gastrulation – The process by which germ layers come to occupy their characteristic positions
germ layers and their systems
Germ Layers and Their Systems
  • Ectoderm
    • Epidermis and lining cells of glands
    • Appendages of skin
    • Nervous system
    • Posterior Pituitary
    • Chromafin organs - adrenal medulla
    • Anterior Pituitary
    • Some Epithelium
  • Entoderm
    • Epithelial lining of alimentary canal
    • Lining cells of glands that open to alimentary canal
    • Epithelium of most of the urinary bladder and urethra
    • Epithelium of prostate
  • Mesoderm
    • Remaining organs and tissues not made by Ectoderm or Entoderm
    • Connective tissue
    • Teeth
    • Musculature
    • Blood
    • Adrenal Cortex
placenta and hormones of pregnancy
Placenta and Hormones of Pregnancy
  • Structure of placenta
    • Include
      • Fetal membranes
      • Maternal membranes
  • Functions of placenta
    • Hormones
      • Role of hormones
      • Hormone Biosynthesis
    • Respiration
    • Protection
    • Excretion
  • Fetal circulation
    • Trace blood flow
    • Know obstacles
    • Know modifications

Yolk Sac

Center of blood formation in early embryonal life

Facilitates transfer of nutrients from developing trophoblast to embryo


Blood vessels develop around allantoic tube

Tube eventually fuses with chorion

By 6th week – 1 umbilical vein and 2 umbilical arteries


Membranous sac that surrounds embryo

Fluid fills amnion that has protective role throughout pregnancy



Highly modified uterine endometrium


Portion between ovum and uterine wall


Region of decidua where ovum is embedded


Lines remainder of uterus

placenta functions
Placenta Functions
  • Gas Exchange
  • Nutrient Delivery
  • Antibody Delivery
  • Removal of Waste
  • Secretion of hormones
  • Protection
hormones of pregnancy
Hormones of Pregnancy
  • Estrogen
  • Progesterone
  • hCG
  • Placental Lactogen (hCS)
  • Placental Growth Hormone
challenges and adaptations
Challenges and Adaptations
  • Challenge
    • Oxygen and Nutrients are less in umbilical vein than in adult arteries
  • Adaptations
    • Establish priorities
    • Establish specific structures to supply priorities
    • Embryonal Hemoglobin
specific structures
Specific Structures
  • Ductus Venosus
    • Shunts Umbilical Vein to Inferior Vena Cava
  • Foramen Ovale
    • Shunts between atria
  • Ductus Arteriosus
    • Shunts pulmonary artery to aorta
nervous system
Nervous System
  • Major Functions
    • Communication with external/internal environment
    • Regulation of…
  • Major Components
    • Neurons
    • Neuroglia
    • Mylenated nerve fibers
    • Microglia
    • Ground Substance
    • Blood Vessels and CSF
development of the nervous system
Development of the Nervous System
  • Morphological Development
  • Biochemical Development
  • Functional Development
  • Sexual Differentiation
  • N.S. – Arises from ectoderm on dorsal portion of embryo
  • 3-4 Weeks – Cells proliferate along middle plate
  • 5-6 Weeks – Plate folds to form neural groove
  • 6-7 Weeks – Groove closes into neural tube
    • Brain develops from anterior portion
    • Spinal cord develops from the posterior portion
neural epithelium
Neural Epithelium
  • Neuroblast
    • Neuron
  • Spongioblast
    • Migratory Spongioblast
      • Oligodendria
      • Astrocytes
    • Astrocytes
    • Ependyma
energy sources

Primarily maternal glucose

Stored as glycogen

Under influence of glucocorticoids

In fetus

Insulin levels high

Insulin sensitivity high


Anaerobic Glycolysis


Glycolitic enzyme

High in postnatal brain

During same period the oxidative enzyme

Succinic Dehydrogenase

Much lower

Energy Sources
thyroid hormone
Thyroid Hormone
  • Functions
    • Promotion of body growth
    • Development of CNS through:
      • Promotion of neorogenesis
      • Promotion of myelination
      • Promotion of brain metabolism
    • Stimulates oxygen consumption in all cells
  • Abnormalities
    • Hypothyroidism
      • Cretinism
      • Short stature, low metabolic rate, skin changes
      • Treatable if given Thyroxine at an early age
functional development
Functional Development
  • Differential Development of N.S.
    • Neurotransmitter activity in different brain regions
  • Perinatal Behavior
    • Reflexes – Refer to table in reader
      • Motor
      • Respiratory (17-24 weeks)
      • Gastrointestinal (24th week)
        • Suckling
      • Startle (Presence of excessive activity after birth is an indicator of delayed development of certain brain centers)
  • Education
    • Better educated appear to live longer with less disability
    • Several pieces of evidence discussed for this in class
sexual differentiation44
Sexual Differentiation
  • Steroid hormone action on brain development
    • Androgen action on sexually dimorphic nucleus of the preoptic area (SDN-POA)
      • Male Rats – After puberty responsible for male behavior, large SDN-POA present
      • Female Rats (low androgen levels) – After puberty -Small SDN-POA (reversible with androgen treatment)
        • Lordosis (arching of back when sexually receptive)
metabolism and growth
Metabolism and Growth
  • Metabolism and Growth information:
    • Reader / Handout
    • Class Today
    • Discussion Today