Reproduction and Development

1. Reproductive Systems

1. Male Reproductive System

1) To produce sperm (spermatogenesis)

2) To produce Androgens (Hormones) responsible for the development of secondary sex characteristics

a) Functions

B) Structures

1. Scrotum- sac that contains the testes (outside body cavity to lower temperature for spermatogenesis)

2. Testes- structures which produce sperm in tightly coiled tubes called the seminiferous tubules

Male Structure

3. Epididymis- structures which rest on top of the testes and hold sperm until maturation is complete

4. Vas deferens- tubes in which sperm travel during ejaculation (muscular contractions which force sperm through the urethra)

Male Structure

5. Seminal vesicles, Bulbourethral gland and prostate add sugars, bases and lubricants to form semen

c) Sperm Structure

• Acrosome- contains enzymes which enable penetration of the egg

• Nucleus- contains chromosomes

• Mitochondria- provide ATP for movement

• Tail- flagella for motility

2. Female Reproductive System

1) To produce ovum (eggs)

2) To produce female sex hormones estrogen and progesterone

3) To protect and nourish the embryo

a) Functions

b) Female Structure

1. Ovaries- produce eggs in oogenesis

2. Fallopian tubes (oviducts) receives egg after ovulation (the release of the egg from the ovary)

3. Uterus- pear-shaped cavity where the zygote (fertilized egg implants and develops)

Female Structure

4. Cervix- muscular ring which supports the embryo during development

5. Vagina- (birth canal) tube that leads from the uterus to outside the body

Ovary

Uterus

Oviduct

Cervix

Vagina

B. Menstrual Cycle- Hormone controlled series of events that produce an egg and prepare the uterus to receive it

1. Hormones and their effect:

  

HORMONE PLACE OF ORIGIN PRIMARY EFFECT

  Hypothalmus Causes Anterior pituitary to release FSH and LH    Anterior Pituitary Stimulates the follicle to begin to grow  

  Follicle (in ovary) Triggers Pituitary to release LH. Also thickens the uterine lining 

  Anterior Pituitary Causes ovulation and formation of the corpus luteum 

  Corpus Luteum Maintains uterine lining and inhibits the production of GnRH

GnRH

Gonadotrophin Releasing Hormone

FSHFollicle Stimulating Hormone

Estrogen

LH

Lutenizing Hormone

Progesterone

Menstrual CycleHypothalamus

GnRH

Anterior Pituitary

FSH LH

Follicle (in ovary)

EstrogenStimulates

Thickens

Uterus

Maintains

Progesterone

Ovulation

Egg (oviduct)

Corpus Luteum (in ovary)

Inhibits

2. If Fertilization and implantation do not occur, the corpus luteum falls apart

A) Progesterone levels decline

B) Uterine lining cannot be maintained triggering menstruation

C) FSH levels increase beginning the next cycle

Menstrual Cycle Timing

C. Fertilization and Development

1. Fertilization- process in which the sperm and egg unite forming a Zygote

2. About 400 million sperm are released into the vagina, about 3000 make it to the oviduct and only about 50 make it to the egg

3. Fertilization occurs in the oviduct and a zygote is formed

4. The process of cleavage (rapid cell division without G2) starts and continues until a round ball of cells is present. This ball is called the morula

5. Cleavage continues and the morula hollows out and becomes a blastula

2 cell stage 4 cell stage

Early Cleavage

Morula Blastula

Late Cleavage

6. The blastula moves down the oviduct and will implant in the thick uterine wall. It is now called a blastocyst

7. Here the process of differentiation (3

new cell layers) occurs • Ectoderm- becomes

epidermis, & nervous system

• Mesoderm- becomes muscles, skeleton, circulatory and reproductive systems

• Endoderm- becomes liver pancreas, digestive and respiratory systems

8. The cell layers pinch in and elongate during gastrulation and a gastrula is formed.

9. Around the Gastrula, four membranes form

A) Yolk sac- produces blood cells in the early embryo

B) Allantois produces blood cells and becomes the umbilical cord

C) Amnion forms the amniotic sac filled with fluid for protection of the embryo

D) Chorion becomes the placenta

10. The placenta delivers nutrients, oxygen and gets rid of wastes through the process of diffusion.

(Note: maternal and fetal blood never mixes.)

11. About 12 days after fertilization, a streak appears on the disc-shaped gastrula. This streak will become the brain and spinal chord12. At the top of the streak, bulges appear that will become the brain. It is now called a neurula (3 weeks)

                                                     

13. 4 weeks after fertilization, the heart develops and begins to beat. It is now an embryo and it is the size of a grain of rice

Heart

4mm

14. The embryo grows and develops the start of arms and legs; but, it still has a tail and branchial arches (gill slits) in its throat

15. At about 2 months, all the main body parts are formed and bone cells are now being produced. It is now a fetus

Sperm Egg

Fertilization

Zygote

cleavage

Morula

Blastula

implantation

Blastocyst

differentiation & gastrulation

Gastrula

neural tube formation

Neurula

heart starts to beat

Embryo

bone begins to form

Fetus

growth and refinement of organs

Baby

16. The fetus will grow over the next 7 months until labor is signaled by contractions of the uterus

A) Dilation phase- the baby’s head pushed by contractions, triggers the cervix to dilate

b) Expulsion phase- the mother forces the baby out the birth canal

c) Placental phase- the placenta is delivered

Birthing Process & Postpartum • Doctor Visits

– Interview/ Risk evaluation– Medications: prenate, glucola

• Birth plan– Setting– Anesthesia– Surgical options:

• Episiotomy? • Circumcision?

• Post Birth– Help– Bottle or Breast

Some Excellent links on Reproduction an Development

• Parents place

• Just the Facts

• The Visible Embryo

• Window on the Womb

• How Sex is Determined

• Life’s Greatest Miracle

D. Care of Babies

1. Birth defects- any mental or physical handicap or something that requires surgery.

a) Genetic defect- any birth defect caused by DNA instructions. (Not Preventable)

1. Chromosomal Abnormality- having too many or too few chromosomes. Usually lethal. Down's syndrome, Edward's syndrome

2. Gene Abnormality- caused by a lack of a protein, Usually less severe than a chromosome abnormality. Examples: Cystic Fibrosis, Sickle cell anemia, Tay Sacs, PKU, Albinism

b) Acquired Birth Defect- any birth defect caused by the actions or inactions of the parents. (100%) preventable.

1. F.A.S.- fetal alcohol syndrome

a) #1 cause of acquired birth defects. Every two days, an FAS child is born in Indiana

b) Low birth weight. Malformation of face and body. Lowered IQ

2. F.T.S.- fetal tobacco syndrome: Lowered birth weight. Lowered IQ

3. Other drugs such as cocaine, LSD and marijuana are linked with birth defects. Even some OTC drugs can be harmful

2. How can birth defects be Prevented?

1. Be Responsible!!!

2. See a doctor early and regularly

3. Stay in shape

4. Eat sensibly with enough from all five food groups

5. Try to relax and enjoy the pregnancy

DO:

Don’t1. Drink alcohol

2. Use tobacco

3. Take illegal drugs

4. Take over the counter drugs without a doctor's consent

5. Have X-rays of the abdominal region

6. Drink a lot of caffeinated drinks

7. Expose yourself to environmental hazards

3. Diagnostic Testing

a. Family History: Blood pressure, heart problems, thyroid problems, diabetes, STDs

b. Mother's condition: weight, age etc….

c. AFP Test: alpha fetal protein is tested from the mother's blood. Used to detect the presence of neural tube defects.

d) Ultrasound- sound waves show baby. Used to determine the development of the organs and the baby's size.

4 D Ultrasound

e. Amniocentesis- fluid and cells are withdrawn from the womb for testing.

f. Karyotype - an arrangement of chromosomes used to detect genetic disorders

g. Fetoscopy- a slender tube inserted into the womb to allow viewing of the fetus