Prenatal Development

Embreyogenesis

Formation and growth of an embryo

Faulty development of pituitary and repro tract development generates

Reproductive failure

Totipotent

Has the ability to form all cell types of conceptus

Pluripotent

After totipotent cell makes choice, it becomes pluripotent and has the ability to form several types of all three germ layers

Multipotent

Has the ability to form a limited range of cells and tissues appropriate to their location

Totipotent cells can become part of

Placenta (trophoblast) or embryo (inner cell mass)

Embryonic disk

Two layers of cells that become the embryo proper

Gastrula

Day 16: Embryo with all three germ layers

Morula

Day 4: Solid ball of cells formed as zygote undergoes cleavage (Splitting)

Early blastocyst

Day 6: Hollow ball of cells with a fluid filled cavity

Late blastocyst

Day 10- Pre-embryo with embryonic disk

Endoderm

Inner germ layer, becomes part of digestive

Mesoderm

Middle germ layer, becomes part of repro system

Ectoderm

Outer germ layer, becomes part of nervous system

The pituitary gland develops from which germ layer

Ectoderm

Anterior pituitary gland develops from

The roof of the embryos mouth (adenohypophysis)

Posterior pituitary gland develops from

Floor of the brain (neurohypophysis)

Pituitary hormones

LH, FSH, PRL, OT

Rathke’s pouch

The pouch that forms with the rise of of the tissue in embryo’s mouth

Fertilization

Initial step in sexual differentiation

When is sex determined?

At fertilization

What sex chromosome does an oocyte have?

X= female

What sex chromosome does spermatozoa have?

Two, Y= male X= female

Which chromosome drives primary sex determination

Male Y

Sex Determining Region (SRY)

Gene on the Y chromosome

SRY Gene →

Transcribes SRY mRNA

SRY mRNA →

Translates SRY protein

2 cells found in the testes

Sertoli and Leydig

Sertoli cells

Found in testes, secretes Anti Mullarian Hormone which supports make gonad

Leydig Cells

Found in testes, secrete testosterone, a steroid producing cell

What happens when there is no SRY gene

The

If there is no SRY, there is no

Anti mullerian hormone

What does an XX male gene indicate

There is an SRY gene present and the individual is phenotypically a male

What does a XY female gene indicate

A mutated or missing sry gene is present and the individual is phenotypically a female (Swyer syndrome)

During early embryo formation, primordial germ cells develop while ____ is still present

Yolk sac

What germ layer do primordial germ cells migrate in?

Mesoderm

How does gonadal sexual differentiation occur?

Through primordial s

gonadal development path

Starts at yolk sac → Allantois → Hindgut → to Gonadal ridge where the sex cords

Mesentery

Paratenium (Holds digestive tract in place)

What renal systems does the embryo utilize

Pronephros, Mesonephros (wolffian ducts), Paramesonephrus (Mullarian ducts), and metanephros

Pronephros

Non functional primitive form of kidney

Mesonephros

Found in male kidneys, produce urine that drains into the mesonephric ducts

Also known and wolffian ducts

Paramesonephric ducts

Found in female kidneys, develop at the same time as mesonephric ducts.

Also known as mullarian ducts

Embryos have both types of what kind of renal systems

Mesonephros and paramesonephric

Metanephros

Final kidney form in development of renal system, develops functional nephrons

Mesonephros is closely associated with which type of gonad

Undifferentiated

Mesonephric duct is retained and forms:

Epididymis and ductus deferens

Paramesonphric ducts are retained and form:

Oviducts, uterus, cervix, and portions of cranial vagina

When the metanephros begins to form a small bud, the mesanephros

Begins to lose function and decrease in size

When the metanephros becomes fully functional, what happens to the gonads

They become larger

When the metanephros becomes fully functional, the mesonephros and mesonephric ducts becomes

Components of the reproductive tract

What is the steroidogenic cell of the testis

Leydig

What is the primordial germ cell of the testis

Spermatogonia

What is the function of supporting cells precursors

Support development of gametes

What are the supporting cells precursors of the testis

Sertoli

What are the steroidogenic cells of the ovary

Theca

What are the primordial germ cells of the ovary

Oocyte

What are the supporting cells precursors of the ovary

Granulosa cells

What happens to the paramesonephric duct in the male repro system?

It gets removed by anti mullarian hormone

Undifferentiated sex cords align themselves with

Small rete tubules

What type of cells produce anti mullerian hormone?

Sertolli cells

Mesonephric duct

Gradually transforms into the epididymis and duct deferens

What happens to female undifferentiated sex cords?

Fragment into cellular clusters in the epithelial cords

Where does the uterus and oviduct develop from?

Mullarian duct

What happens to the rete tubular structures in the female reproductive systen?

Disintegrate because they are no longer needed

Female primordial follicles

Oocyte surrounded by layers of support cells

What structures are formed by the mullarian ducts

Cranial vagina, cervix, uterus, and oviducts

External vs internal female genitalia

External: vulva

Internal: Vagina

Female sex cords differentiate into

Primitive follicular cells

The majority of the gonadal ridge becomes

Ovarian tissue

When is the development of ovarian follices maximized

Prenatal life

Reproductive ducts of a female develop from

Mullarian ducts

Why don’t females have testosterone

Because they don’t have Anti Mullarian hormone

Alpha fetoprotein has a high affinity for

Estrogen

Where does the surge center develop and why

Only in the female hypothalamus because alpha fetoprotein prevents estrogen from entering brain so hypothalamus becomes feminized

GnRH

Hormone released from hypothalamus