Back to Human Anatomy Page

                                                      Growth and Reproduction

Cell Division

              For growth and repair of _______________________

              Somatic Cell division

              Single cell duplicates itself


              Nucleus divides after chromosomes are _________________


              Division of _____________________

Cell Division

Process ensures each new cell has the same number of chromosomes as the _________________

Chromosome number

              23 ________ of chromosomes

              46 chromosomes

              Found in each somatic (_________) cell


Deoxyribonucleic Acid

              Two strands of nucleotides twisted about each other

              Double Helix = twisted ladder


              Nitrogenous bases

              Make “rungs of the ladder”

Nitrogenous Bases

              Adenine                 Thymine

              Cytosine                 ______________

              Ordering of nitrogenous bases determines code of inheritance

Bonding Pairs


              Information for a particular trait is called a ___________

              Made up of a long series of bases on DNA

Some Genes Turned Off

              Each somatic cell contains all the genes to make a complete individual

              Most genes turned off except those involved with the particular cells function


              30,000 or more genes per chromosome

Chromosome Structure

              Each chromosome is composed of a pair of structures called a chromatid



              Attaches each chromatid

              Appears as a small ___________________









              Stages of cell division

              Divided into phases




              The phase that exists when the cell is going about the process of life

              _________________ phase

              Stage when RNA is manufactured in nucleus and passes to cytoplasm

              Several parts to interphase


Phases of Interphase

              G1 (Gap or Growth)

              S (Synthesis)

                            DNA Uncoils and Unzips

                            New Bases Attach

                            Original DNA becomes two

              S phase

              DNA unzips and is ________________________

              Phases of Interphase

              G2 (Gap or Growth)

              Cells engages in growth, metabolism and production of substances for division


              Occurs after G2 and Before G1

Four stages of Mitosis

              IPMAT (Interphase completed)






              ___________Stage of Mitosis

              1.  Chromatin shortens into chromosomes

              2.  Chromatid pairs begin migration to equatorial plane

              3.  Centrioles migrate to opposite ends of nucleus

              4.  Nuclear envelope become less distinct

              5.  Mitotic spindle forms


              Second stage of Mitosis

              Duplicated chromosomes line up in plane ____________________________________

              Remain attached to microtubules of mitotic spindle


              Third stage of mitosis

              Division of centromeres

              Movement of ID chromatids to ___________________ poles





              Fourth phase of mitosis

              Reverse of ___________________

              1.  Chromosome become chromatin

              2.  Nuclear membrane forms

              3.  Mitotic spindle disappears

              4.  Centrioles replicate


              Cleavage furrow appears late anaphase and ends in telophase


Daughter Cells

              Identical cells result from one original cell

Aging Theories                                                                                                                                           

               Genetic = DNA programed to cease in cell division

              50 divisions in Fetal Cells

              HeLa cells continue to divide

              Free radical theory

              O- restricts nutrient uptake and waste removal

              Body regulatory mechanisms stop working

              Immune system starts attaching own cells

              Pituitary gland secrets “some” hormone that causes aging



              Occurs only in __________________(ovary, testes)

              Results in cell with ½ the number of chromosomes of parent cell

              Spermatogenesis in _______________

              Oogenesis in females


Parent cell is diploid (2n)

              Has a duplicate pair of homologous chromosomes

              Homologous = ________________


Gametes (egg and sperm) are haploid

Half of diploid = (n)


              Occurs in the _____________________________________


              2n precursor cell

              Undergoes mitosis

              One daughter remains as _________________

              The other cell enlarges and moves toward center of tubule

              Daughter Cell Enlarges and move toward lumen

Primary Spermatocyte (2n)


46 chromosomes line up at equatorial plane

              Have synapsis


              Pairing of homologous chromosomes

              Form a __________________

Tetrad is a _________chromatids

Crossing over

              May exchange pieces of chromatid at this point

              This increases variation in ________________

First Reduction Division


              Primary spermatocyte divides into two __________________spermatocytes

              No replication of DNA

              Secondary spermatocyte (1n)

               But chromatids attached

Second Reduction Division (Meiosis)

   Splitting of centromeres

              Spermatids (1n)

              Single chromatids



                            Associated with microtubules and centrioles

                            Used for _________________

              Head with nucleus

              Acrosome (____________)

                            Contains ______________________

                            Use to penetrate egg

Sustentacular Cells


              Associated with daughter cells

              Protect sperm from _____________________________

Sperm formation

              Mature sperm formed in ________ hours to __________ days

  Stored in epididymis


              Production of the female gamete

              Occurs in the ___________________



Undergoes mitosis

Becomes primary oocyte by ______________ as embryo

              Primary Ooctye

                            Remain until FSH from pituitary

                            Follicle Stimulating Hormone

                            Causes several follicles to grow

              Secondary Ooctye

                            Receives most of _______________

                            Released with first polar body at ovulation

End result of oogenesis

              End result is diploid ovum with __ polar bodies

              Ovum = Zygote

Sperm vs Oocyte formation

              One ovum result of Oogenesis

              _____________ sperm result of Spermatogenesis



Developmental Anatomy


              Sequential formation of body structures

              During prenatal period of life

              Begins with fertilized oocyte and progresses to total individual

Stages of Morphogenesis

              Pre-embryonic stage (________________)



              Embryonic growth

                            Fetal growth


Fertilization occurs in _______________________

              Occurs 12-24 hours after ovulation

              Egg survives_________ hours

              Three day trip down uterine tube

              Fertilization in distal ___________ of tubule



                            Process where sperm makes contact with secondary oocyte

                            = ________________


                            Fertilized egg moves down uterine tube

                            By motion of fluid moved by _______

                            And uterine tube peristalsis



              Secondary Oocyte survival

                            24 hours

                            Disintegrates if not fertilized

              Sperm survival

                            ________________ hours

                            Move by flagellar action

                            Uterine contractions

                            _______________ per ejaculate

Sperm requirements

              Must be in female __________ hours before able to fertilize egg


              Process where acrosome membrane becomes fragile and releases enzymes

Enzymes of acrosome

              Acrosin = enzyme that increases sperm _______________



              Both dissolve material covering the secondary oocyte

Secondary oocyte and coverings

              Zona pellucida

                            Gelatinous Covering



              Zona Radiata

                            _____________ cells



                            Chromosomal material from male and female

                            Each have a pronucleus

                            Fuse into segmentation nucleus

               No Further Sperm Entry

                            Ionic (electrical) change in cell membrane

                            Sperm receptors on cell membrane altered and other sperm detach


              Dizygotic (fraternal) twins

                            Two different oocytes fertilized by two different sperm

              Monozygotic (Identical) twins

                            Single fertilized oocyte that splits and forms identical individuals

              Conjoined (Siamese) twins

                            Share one or many organs

                            Usually monozygotic

 After zygote is formed

              Structure begins trip down uterine tube

              Starts _________divisions

Cleavage of zygote

              Zygote remains in zona _______________

              Divides into two cells in _____ hours

              Daughter cells called blastomeres

Two Blastomeres (Daughter cells) in 36 hours

Four Blastomeres Day 2

16 Blastomeres = Morula  Day_________

              Solid mass of __________ Identical cells

              Overall size same as ______________

              Blastomeres are smaller with each division

                            Cell division but no growth

                            Morula not attached but has entered uterine cavity

Embryo Transfer

              Actually transfer of _____________

              Can be frozen

              Implanted at a later date

In Vitro Techniques

              In Vitro fertilization (IVF)

                            Retrieve several 2ndary oocytes

                            Put in dish with sperm

                            Put morula back in uterus

              Gamete intrafallopian transfer (GIFT)

                            Immediately put zygote into uterine tube after in vitro fertilization

                            Mimics normal trip down ____________________________

              Transvaginal oocyte retrieval

                            Needle placed through vaginal wall to capture oocytes



 Morula takes on fluid from uterus

              Becomes a fluid filled ball of cells


                            Zona pellucida degenerates

                            Outer layer of cells = Trophoblast

              Inner Cell Mass = Embryoblast

              Cavity called Blastocoel


 “Uterine Milk”

              Secretions from _______________________ that nourish embryonic cells


              1/100 inch

              Endometrial gland


              __________days post fertilization

              Trophoblast divides into two layers


                                          Secretes enzymes to digest endometrium

                                          Nucleated mass with no _____________________________


                                          Distinct cell boundaries

                                          Inner layer


              Grows “___________________” extensions into endometrium

              Eventually becomes______________________


              Digest endometrial lining of uterus

              Blastocyst sinks into endometrium

              Covered by endometrial cells ( Implantation)

Embryonic Period

              First two months or______________ weeks

Inner Cell Mass

              Differentiates into _____________ primary germ layers

              After implantation

              Process call Gastrulation

Primary Germ Layers

              Ectoderm forms as trophoblast divides into syncytiotrophoblast and cytotrophoblast

              Closer to amniotic cavity

Amniotic Cavity



Endoderm next to Ectoderm

              Forms closer to blastocyst cavity

Embryonic Disc

              _____________ layers

              Endoderm plus ectoderm




Other Membranes form

              Amnion from _______________________ layer of inner cell mass

              Yolk sac from Endodermal layer of inner cells mass

Three sacs at this Stage




Mesoderm forms by day 14

              Splits to form extra embryonic coelom

Primary Germ Layers

              Endoderm becomes epithelial lining of :

                            Digestive tract

                            Respiratory tract

              Mesoderm forms:



                            Connective Tissue

              Ectoderm forms:


                            Nervous system

Extra Embryonic Membranes

              Chorion (Chorionic Villi)

                            From Cytotrophoblast

                            Fetal part of placenta

              Decidua Basalis = Maternal Placenta

              Yolk Sac from Endoderm

                            Contains nutrients for some species (birds)

                            Produces blood until _______________ forms

                            Contains all cells that will make gametes

                            Becomes part of umbilical cord


                            Fluid (AF) mostly filtrate from ________________ blood

                            Fetus adds fluid during development

                                          Shock absorber for fetus

                                          BOW “bag of waters”

                                          Regulate fetal body temperature

                                          Prevent adhesions


Surgical puncture with a needle to remove AF and chemicals and cells sloughed from fetus


                            Projection from _________________

                            Associated with blood formation

                            Becomes umbilical cord vessels




              Umbilical Cord

                            Two umbilical ________________

                            One umbilical ________________

                            Whorton’s jelly surround cord

              Which vessel is higher in Oxygen

                            Arteries carry blood FROM the fetal heart

                            Veins carry blood TO the heart (from Mom)