ANS 220 Exam 2

What does the inner cell mass in an embryo become?

Fetus

What does the trophoblast in a embryo become?

placenta

What type of hormone is Human Chorionic Gonadotropin (hCG)?

glycoprotein

What species is human Chorionic Gonadotropin found in?

primates

Majority of the embryonic hormones are produced by…

the placenta

What does hCG and eCG stimulate?

the gonads

Where is the human chorionic gonadotropin hormone produced?

in the trophoblastic cells of the blastocyst (placenta)

What hormone does pregnancy tests test for in urine?

Human chorionic gonadotropin

What are the roles of human chorionic gonadotropin?

Stimulates P4 production from CL

Indirectly blocks luteolysis

Causes ovulation in non-primate females

Increases fetal growth

How early can human chorionic gonadotropin be detected?

as early as 8 days of gestation

What is another name for Equine Chorionic Gonadotropin (eCG)?

Pregnant Mare’s Serum Gonadotropin (PMSG)

What type of hormone is equine chorionic gonadotropin?

glycoprotein

What produces eCG?

endometrial cups of the placenta

What specific cell produces eCG?

chorionic girdle

What are the function of eCG?

formation of CLs which increase P4 production

indirectly blocks luteolysis

acts like FSH in other species

Is eCG the signal of maternal pregnancy?

no (maternal recognition in mares is shown on day 14-16, which is before the peak of eCG)

What day does eCG peak at?

35 days

What type of hormone is Interferon Tau (IFNT)?

Glycoprotein

What type of animals is INFT found in?

Only ruminants

What produces IFNT?

trophoblastic cells of the blastocyte

What is the functions of IFNT?

inhibits oxytocin receptors in the endometrium (blocks smooth muscle contractions)

prevents PGF2a synthesis (allows for the survival of CL)

Promotes protein production to nourish conceptus

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What would happen if you increase GnRH levels?

LH and FSH would increase

ovulation/rupture of the follicle would occur

What would happen if you give a single injection of oxytocin?

No changes to GnRH levels since GnRH is released from the anterior pituitary and not the posterior pituitary like oxytocin

What would happen if you gave a single injection of estrogen?

GnRH levels would increase, which would cause LH levels to increase

The follicle on the ovary could also rupture

What would happen if you disconnect the hypothalamic portal system?

LH, FSH, and testosterone levels would decrease, and GnRH levels would increase

What would happen to hormones if you castrate bulls at birth?

There would be an increase in LH because of the decrease in testosterone

What would happen to hormones in a postmenopausal female?

there would be an increase in LH levels because of a decrease in estrogen

What would happen to hormones if there was continuous testosterone injections?

GnRH, LH, and FSH would decrease, and testes would shrink because of feedback to the hypothalamus

What would happen to hormones if progestin supplement is given?

GnRH and LH levels would decrease and ovulation would be blocked

What would happen to hormones if PGF2a is given?

GnRH and LH would increase and P4 would decrease, which would lead to the loss of pregnancy

What would happen to hormones if an aromatase inhibitor was given?

Would cause masculinity in females and a reduction in sperm production

What would happen to hormones if a 3-b HSD inhibitor was given?

No progesterone would be produced and there would be a reduction in pregnancies

What are the three layers of the reproductive tract?

ectoderm, mesoderm , and endoderm

What is the outermost layer of the repro tract?

ectoderm

What is the muscular layer of the repro tract?

mesoderm

What is the innermost layer of the repro tract?

endoderm

What does the ectoderm consists of?

hypothalamus, nervous system, skin, hair

What does the mesoderm consists of?

muscle, skeletal, cardiovascular, and reproductive system

What does the endoderm consists of?

digestive system, lungs, endocrine system

How is the anterior and posterior sections of the pituitary developed?

1. The oral portion of the mouth starts to reach for the infundibulum
2. Infundibulum and Rathke’s pouch touch
3. Stalk of Rathke’s pouch regresses
4. Rathke’s pouch wraps around the posterior pituitary
5. Bone encloses the anterior pituitary

What turns into the posterior pituitary?

infundibulum

What turns into the anterior pituitary?

Rathke’s pouch

What would happen if you cut out Rathke’s pouch?

there would be no growth hormones or gonadotropins

What are the two cell types?

somatic cells and germ cells

What are somatic cells?

all cells in the body except germ cells

autosomes

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Do somatic cells undergo mitosis or meiosis?

mitosis

Are somatic cells diploid or halploid?

diploid

How many chromosomes do cattle have?

60

How many chromosomes do horses have?

64

How many chromosomes do swine have?

38

How many chromosomes do humans have?

46

How many chromosomes do sheep have?

56

What are germ cells?

oogonia and spermatogonia formed from primordial germ cells

Are germ cells diploid or halploid?

haploid

Do germ cells undergo mitosis or meiosis?

both

Overview of mitosis…

produces two identical daughter cells

only 1 phase

Overview of meiosis…

2 phases

only in germ cells

Meiosis 1: exchange or alteration of genetic material between homologous chromosomes

Meiosis 2: just like mitosis

What cells have a high rate of mitosis?

epithelial lining of the gut

What cells have a low rate of mitosis?

brain cells

Germ Cell Migration (Know the labels)

What is the purpose of the yolk sac?

nutrient source of fetus

origin of the primordial germ cells

What is the purpose of the allantois?

waste holder

What is the purpose of the gonadal ridge?

where the primary sex cords are formed

What is the nephros?

Duct that will become kindey

What is the germ cell migration?

1. germ cells start at the yolk sac
2. They migrate through or pass the hindgut
3. they enter the gonadal ridge and start to undergo mitosis
4. primordial germ cells are sealed off by the tunica albuginea forming an indifferent gonad

What is an indifferent gonad?

neither a female or a male (sex determination has not been determined)

What are the names for the male duct?

mesonephros or wolfian duct

What are the names for the female duct?

Paramesonephros or Mullerian duct

What happens if you remove the ovaries from a female fetus?

You get a female adult

What happens if you remove the testes from a male fetus?

You get a female adult

What is the determining factor of a Y chromosome?

SRY (sex determining region)

What is testis determining factor?

synthesized by developing sex cords

causes differentiation of sertoli cells

What do male Sertoli cells produce?

anti-mullerian hormone and testosterone

What does the mesonephros duct form?

rete testes

efferent ducts

epididymis

vas defernes

Does the mesonephros contain AMH and androgens?

Yes

Does the paramesonephros contain AMH and androgens?

No

Which tract develops first?

male tract

What is anti-mullerian hormone (AMH)?

a hormone that causes regression of the mullerian tract

What does the paramesonephros tract from?

oviducts

uterus

anterior vagina

Wolfian tract development (know the labels)

Mullerian tract development (Know the labels)

What happens to the mullerian duct in the wolfian duct formation?

it regresses

What happens to the wolfian duct in the mullerian duct formation?

it regresses

What happens in ovary development?

primary proliferation in the medullary region

PGC in the medulla is lost

Why is there a fixed number of cells in the ovary?

Secondary proliferation only occurs in the inner hollow of the cortex

How is sex determined?

1. Female egg cells contain an X chromosome
2. Half of the male’s sperm cells have an X chromosome and half of them have a Y chromosome
3. An egg cell fertilized by a sperm cell containing a Y chromosome develops into a boy
4. An egg cell fertilized by a sperm cell containing an X chromosome develops into a girl

What does external genitalia developed from?

ectoderm

What is external genitalia regulated by?

sex steroids

External Genitalia (picture)

What are some sexual dimorphisms?

growth rates

body size

muscle vs adipose

hair growth

How does sex influence the brain?

Can cause behavioral changes (masculine vs. feminine)

Steroids can impact (high stress can increase cortisol which can increase masculinity)

intrauterine environment (male fetus in between two females will see more estrogen and vise versa)

What does aplha-fetoprotein bind to?

estrogen

What would happen if there was a lack of alpha-fetoprotein?

estrogen would be able to enter the hypothalamus and knock out the surge center

What is the process to knock out the surge center in males?

1. the gonads release testosterone and it travels to the hypothalamus
2. testosterone is lipophilic and can transport through the cell membrane
3. testosterone is converted to estrogen due to an increase in aromatase
4. Estrogen regresses surge center

What is the process for the tonic and surge center in the female?

1. the gonads release estrogen and it travels to the hypothalamus
2. estrogen binds to alpha-fetoprotein which causes them to be rejected from passing through the blood brain barrier


1. Both the surge center and the tonic center can develop

Where is alpha-fetoprotein present?

in both males and females

Why is there an increase of the pre-optic area in males only?

since males do not have a surge center, there is more room for development of the pre-optic area

What are the three types of intersexuality?

freemartins

true hermaphrodite

pseudo-hermaphrodite

What animal can be a freemartin?

only cattle

What animals can be a true hermaphrodite?

some fish