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.