Reproductive

Question 1

Describe the hypothalamic-pituitary-gonadal axis

Answer 1

Hypothalamus releases gonadotropin releasing hormone (GnRH) that stimulates the anterior pituitary

Anterior pituitary will release follicle-stimulating hormone (FSH) and Luteinizing hormone (LH) from gonadotrophs (cell type in anterior pituitary)

FSH and LH act on the ovaries to release progestins and estrogens, and on the testes to release androgens

Progestins, estrogens, and androgens then go to target tissues throughout the body as well as providing feedback on this axis

Question 2

GnRH is under negative feedback by

Answer 2

Steroid hormones (progestins, estrogen, androgens)

Question 3

Follicle stimulating hormone (FSH) acts on what cells in the ovaries and what cells in the testes and stimulates what in these organs?

Answer 3

Ovarian granulosa cells - stimulates follicular development

Sertoli cells in testes - aids spermatogenesis

Question 4

Negative feedback for FSH and LH comes from what?

Answer 4

Steroid hormones and inhibin

There is a point at which rising estrogen actually causes positive feedback on LH to cause LH surge during ovulation

Question 5

Luteinizing hormone acts on what cells in the ovaries and testes to stimulate what?

Answer 5

Ovaries - multiple, but remember LH SURGE ACTS ON OVARIAN GRANULOSA CELLS to stimulate ovulation; LH will also cause ovaries to produce steroid hormones

Testes - Leydig cells - steroid hormone synthesis

Question 6

What are the three major roles of estrogens?

Answer 6

Fertilization
Pregnancy preparation and pregnancy
Long-term effects on physiology

Question 7

How do estrogens influence fertilization?

Answer 7

Increase estrous behavior in some species

Increase uterine contractility

Open cervix to admit sperm

Question 8

How do estrogens influence pregnancy preparation and pregnancy?

Answer 8

Stimulates endometrial development

Increase uterine progesterone receptors

Increases GnRH leading to LH surge that results in ovulation

Question 9

What long-term effects do estrogens have on physiology?

Answer 9

Female secondary sex characteristics

Question 10

What are the three major roles of progestins in the body?

Answer 10

Fertilization

Preparation for pregnancy and pregnancy

Lactation

Question 11

How do progestins impact fertilization?

Answer 11

Decrease uterine contractility

Close cervix

Decrease FSH secretion

Question 12

How do progestins influence preparation for pregnancy and pregnancy?

Answer 12

Increase uterine musculature

Increase endometrial gland secretions

Question 13

How do progestins influence lactation?

Answer 13

Stimulates development of mammary alveolar cells

Inhibits milk production

Question 14

What are the three roles of androgens in the body?

Answer 14

Spermatogenesis

Fertilization

Long-term effects on physiology

Question 15

How do androgens influence spermatogenesis?

Answer 15

Actions on Sertoli cells

Maintenance of efferent ductular system

Maintenance of accessory sex glands

Question 16

How do androgens influence fertilization?

Answer 16

Promote sexual behavior

Question 17

What are the long-term effects of androgens on physiology?

Answer 17

Male secondary sex characteristics

Anabolic effect (promotes growth)

Question 18

Where is prolactin produced?

Answer 18

Anterior pituitary

Question 19

What does prolactin do?

Answer 19

Promotes lactation and maternal behavior, inhibits follicular development

Question 20

Where is oxytocin produced?

Answer 20

Produced in hypothalamus and released from posterior pituitary

Question 21

Where is inhibin produced?

Answer 21

Granulosa and Sertoli cells

Question 22

What does inhibin do?

Answer 22

Selectively inhibits FSH (not LH)

Question 23

In reproductive physiology, prostaglandins are most often considered in the context of __

Answer 23

Luteolysis

Question 24

The follicular phase is divided into

Answer 24

Proestrus and estrus

Question 25

What is the dominant hormone during the follicular phase

Answer 25

Estrogen

Question 26

What happens during proestrus?

Answer 26

Early follicular development
Gamete maturation

Question 27

What happens during estrus?

Answer 27

Final follicular development and sexual receptivity

Question 28

What are the phases of the reproductive cycle?

Answer 28

Follicular phase (proestrus, estrus)
Ovulation
Luteal phase (metestrus, distrusted, luteolysis)

Question 29

When does ovulation occur

Answer 29

End of estrus (shortly after end of estrus in some species)

Question 30

What triggers ovulation?

Answer 30

LH surge (which is in turn triggered by rising levels of estrogen inducing positive feedback of GnRH in the hypothalamus)

Question 31

What happens during ovulation?

Answer 31

Ovum is released into oviduct to encounter sperm for fertilization

Question 32

The luteal phase is divided into __ (3 stages)

Answer 32

Metestrus
Diestrus
Luteolysis

Question 33

What is the dominant hormone during the luteal phase of the reproductive cycle?

Answer 33

Progesterone

Question 34

What happens in metestrus

Answer 34

Formation of corpus luteum
Transition from estrogen to progesterone dominance

Question 35

What happens during diestrus

Answer 35

Corpus luteum is functional. And produces progesterone to prepare uterine environment to be favorable to pregnancy

Question 36

What happens in luteolysis?

Answer 36

Destruction of corpus luteum and termination of luteal progesterone secretion

Question 37

What are indications for vaginal cytology in female dogs?

Answer 37

1. Evaluate inflammation in caudal reproductive tract
2. Evaluate hemorrhagic discharge in caudal reproductive tract
3. Look for evidence of malignancy in caudal reproductive tract
4. Determine stage of reproductive cycle

Question 38

What happens to cells on canine vaginal cytology around ovulation?

Answer 38

Become anucleate superficial epithelial cells aka cornified cells

Ovulation typically coincides with the finding of 70-90% cornified cells on cytology

Question 39

Answer 39