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Male and Female Reproductive Structures,
Menstrual Cycle, and Development
Male Reproductive Structures
Male Reproductive Structures• Testis – site of sperm
production– produces hormone testosterone
• Scrotum – sac containing testes– maintains testis at 1-3°C below
body temperature
• Epididymus – site of sperm maturation
• Vas deferens – carries sperm from testes to urethra
• Fluid from 3 glands combine with sperm to make semen
• Seminal vesicle, prostate gland, and bulbourethral (Cowper’s) gland – Adds sugar, lubricants, and neutralizing fluid– Sperm + fluids = semen
Male Reproductive Structures
• Urethra – carries urine and semen out of the body
• Penis – external reproductive organ
Male Reproductive Structures
Seminal Vesicle
Bulbourethral Gland
Bladder
Epididymus
Scrotum
Penis
Testis
Urethra
Prostate
Vas Deferens
Female Reproductive Structures
• Ovaries – contains follicles where eggs (ova) mature
Female Reproductive Structures
– produces estrogen and progesterone
• Egg travels down the fallopian tube (oviduct) to the uterus
• Cilia lining fallopian tubes - sweeps egg into the uterus– Fertilization is usually here
• Uterus (womb)– Muscular organ where fetus develops– Contracts during birth
• The cervix connects the uterus/vagina
• Vagina – birth canal
Female Reproductive Structures
Ovary
Fallopian Tube
Uterus
Cervix
Vagina
Bladder
Urethra
Anus
Labia MinorLabia Major
Clitoris
Uterus
Ovary
Cervix
Fallopian Tube
Vagina
Menstrual Cycle Summary• Regulated by negative feedback • Follicular phase
– Pituitary responds to low estrogen levels releases FSH & LH
– Follicle (egg) develops, and releases estrogen• Ovulation
– Shortest phase– FSH/LH peak,
follicle ruptures, egg releases
Menstrual Cycle Summary• Luteal Phase – corpus
luteum releases estrogen and progesterone– Uterine lining builds up– Fertilization may occur
• Menstruation occurs if egg isn’t fertilized– Corpus luteum breaks down– Estrogen and progesterone decrease– Blood, tissue, and egg leave thru the vagina
• Low estrogen levels cause pituitary to release FSH & LH… the cycle repeats
EggOvary
Oviduct
Uterine wall
Fertilization and Implantation• Fertilization occurs in the oviduct
– Zygote – a fertilized egg, diploid cell
Zygote
Morula
2 cells4 cells
FertilizationBlastocyst
Implantation
• Cell division begins– Embryo - > 1 cell– Morula – solid ball of 64 cells– Blastocyst – hollow ball of cells
• Blastocyst takes ~7 days to implant in the uterine lining
• Differentiation begins, cells specialize
Embryonic Development• Gastrulation is the formation of 3 embryonic
germ layers• Endoderm – lining of digestive, reproductive,
respiratory systems• Mesoderm – muscles, blood, and bones• Ectoderm – skin and nervous system
Human Development Video clip Link
• http://www.youtube.com/watch?v=UgT5rUQ9EmQ
For complete internal development to occur, there must be a continuous food supply, gas exchange, and waste removal.
Placental mammals supply these needs with a placenta.
Examples: humans, dogs, rats, horses, and deer.
Placental Mammals
The Placenta
Pregnancy and Development• Specialized embryonic membranes develop to protect
and nourish the embryo• Chorion – develops into the placenta • Placenta and umbilical cord connect fetus to mother
– Provides energy and O2, removes wastes and CO2
Pregnancy and Development• Amnion develops into the amniotic
sac which cushions the fetus
Placenta and Umbilical Cord The embryo is
connected to the placenta by an umbilical cord which contains large blood vessels that transport food, oxygen, carbon dioxide, and wastes between the mother and fetus.
Embryo = 0-8 weeksFetus = after 8 weeks
Stages of Pregnancy – 3 Trimesters
Fetal Growth and Development• 1st Trimester – all organ systems formed by 7th week
• 2nd Trimester – organs mature, heart can be heard
• 3rd Trimester – greatest size and mass increase
5 Weeks 9 Weeks
14 Weeks 20 Weeks
Birth The hormone oxytocin causes a series of uterine contractions to begin (labor.)
The amniotic sac breaks, the cervix dilates, and as the contractions become more intense the fetus is pushed head first and face down through the birth canal.
The birth is followed by afterbirth or expulsion of the placenta. The umbilical cord is cut and tied immediately after birth.
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