Week 1: Conception and Fetal Development

1

Fallopian tube

2

Fundus

3

Uterus

4

Ovary

5

Uterine wall

6

Vagina

Oocyte

Immature female reproductive cell

Ovum

Mature female reproductive cell

Gametogenesis—Oogenesis

the process of egg/ovum formation from an oocyte

Ovulation

Phase in the menstrual cycle where the ovary releases an ovum (egg)

• one primary Oocyte matures monthly

Zygote

Ovum (egg) that is fertilized by sperm

Vaginal exam

2 fingers up cervix and examine the thickness and consistency

Gonadotropin-releasing hormone

hormone produced in the hypothalamus that stimulates the the anterior pituitary gland to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH)

Follicle-stimulating hormone (FSH)

Hormone produced by the anterior pituitary gland that stimulates the growth, development, and maturation of ovarian follicles that contain the egg

Luteinizing hormone (LH)

hormone produced by the anterior pituitary gland that is essential for reproduction, triggering ovulation and progesterone production in women

Progesterone

Released during menstruation and promotes thickening of the uterine lining and creating a good environment for a fertilized egg to implant

• Progesterone = Pro-gestation

Order of hormone elevation during menstrual cycle

1. Gonadotropin-releasing hormone

2. Follicle-stimulating hormone

3. Luteinizing hormone

4. Progesterone

1

Bladder

2

Vas deferens

3

Urethra

4

penis

5

testes

7

Ejaculatory duct

8

prostate gland

Structures in order of sperm’s path until ejaculation

1. Epididymis

2. Prostate

3. Testes

4. Urethra

5. Vas deferens

6. Seminal vesicles

3 - Testes

1 - Epididymis

5 - Vas deferents

6 - Seminal vesicles

2 - Prostate

4 - Urethra

Zona pellucida

Plasma membrane around an ovum that binds to sperm and engulfs it and prevents other sperm from binding by releasing chemicals

***Travel in fallopian tube to implantation in uterus

• zygote

• Cleavage

• Morula

• Blastocyst

1. Zygote — fertilized egg that is in the fallopian tubes

2. Cleavage

3. Morula

4. Blastocyst

Morula

16-cell cluster of cells formed through cell division that occurs after the formation of a zygote through fertilization

Blastocyst

an embryo that has developed for five to seven days after fertilization that is a spherical structure with a fluid-filled cavity

Trophoblast

blastocyst's outer layer, forming the placenta

1

Decidua

2

Endometrial gland

*3

Maternal vessel

*4

Chorionic villi

5

Trophoblast

6

Syncytium layer

7

Cytotrophoblastic layer

Chorionic Villi (CV)

fingerlike projections that extend into the endometrium

Chorionic villi functions

• Obtain oxygen and nutrients from maternal blood stream

• Dispose of CO2 and waste products into maternal blood stream

3 stages of fetal development

1. Germinal (weeks 1-2)

2. Embryonic (weeks 3-8)

3. Fetal (week 9 to birth)

When is the most important time during development of organ systems and main external features?

embryonic

• by the end of the embryonic period, all organ systems and external structures are present

Teratogen

agent that acts directly on the developing fetus, causing abnormal embryonic or fetal development

Chorion

the outer cell membrane of the fetal membrane that forms the amniotic sac

• toward the uterus that develops from the trophoblast

• becomes the covering of fetal side of the placenta

• contains major umbilical BVs

Amnion

inner cell membrane of the fetal membrane that forms the amniotic sac

• develops from interior cells of the blastocyst

• becomes the covering of the umbilical cord

• covers chorion of the fetal surface of the placenta

Amniotic fluid functions

• Maintains temp

• Is a source of oral fluid

• Is a repository for waste

• Protects fetus from trauma

• Allows for freedom of movement assisting musculoskeletal development

Placenta

Flattened circular organ in the uterus of females, nourishing and maintaining the fetus through the umbilical cord

Placenta functions

produce hormones and metabolic functions

Hormones produced by the placenta

• hCG — human chorionic gonadotropin

• Human placental lactogen

• Progesterone

• Estriol (estrogen)

Metabolic functions of the placenta

• Respiration

• Nutrition

• Excretion

• Storage

Progesterone function in placenta

helps keep uterine smooth muscle loose to prevent contractions and miscarriage

Estrogen function in placenta

• Promotes uterine growth

• Increases BF to uterus — BV dialation

• Supports fetal organ development

• Placental angiogenesis

Viability

ability of the fetus to survive outside the uterus

• legally viable is when the baby is born < 20 weeks and < 500 g

Umbilical cord

2 arteries deliver deoxygenated blood to placenta

Single vein returns oxygenated blood to fetus

Why are there holes in fetal hearts?

To increase BF and O2 to the brain

Holes in the fetal heart

The liver is bypassed by the _____ _____

ductus venosus

Ductus venosus

a shunt that allows oxygenated blood in the umbilical vein to bypass the liver and is essential for normal fetal circulation

The lungs are bypassed by the ____ ____ and ____ ____

foramen ovale and ductus arteriosus holes in the heart

Hematopoietic system

Process of blood cell development in fetus that begins in liver in 6th week

Pulmonary surfactants

• Lecithin (L)

• Sphingomycin (S)

Lecithin surfactant

most critical surfactant required for postnatal lung expansion

Proper Lecithin (L)/Sphingomyelin (S) (L/S) ratio

2:1 is considered mature

• about 35 weeks gestation

How can L/S be tested?

testing amniotic fluid

Hepatic system

Renal system

Neurological system

Endocrine system

Reproductive system

Musculoskeletal system

Integumentary system

Immunologic system