This document provides information about reproductive hormones in various species. It includes tables listing the estrus cycle lengths and stages for different animal species. It also classifies reproductive hormones by their origin (hypothalamic, pituitary, gonadal, uterine/placental) and describes their biochemical structures, biosynthesis pathways, target tissues, and primary actions in males and females. Hormones discussed include GnRH, FSH, LH, estradiol, progesterone, testosterone, PGF2α, relaxin, hCG, eCG, and placental lactogen.

1. Complete the table with respective data
1
Species Cycle
length
(d)
Proestrus
(days)
Estrus
(days)
Metestrus
(days)
Diestrus
(days)
Cow
Buffalo
Sheep
Goat
Mare
Bitch
Cat

2. CLASSIFICATION OF REPRODUCTIVE
HORMONES
2

3. Positive and Negative feedback
(Controller of Hormone)
-ve feedback = suppression of GnRH neurons
+ve feedback = Stimulation of GnRH neurons
3
E2 GnRH (surge) LH surge = Ovulation

4. Classification of Hormones
Hypothalamic
hormones
(GnRH,
Oxytocin)
Pituitary
hormones
(FSH, LH,
Prolactin)
Gonadal
hormones (E2,
P4, Testosteron,
Inhibin, relaxin,
androgens)
Uterine or
placental
hormones
(PGF2α, P4,
E2, eCG,
hCG)
4
Source/Origin

5. Mode of
Action
Neurohormone
(Oxytocin)
Releasing hormones
(GnRH)
Gonadotropins
(FSH, LH)
Sexual promotors (E2,
P4, Testosterone)
Pregnancy maintenance
hormones (P4, placental
lactogen)
Metabolic
hormones
(Thyroxin, corticoid,
somatotropin)
Luteolytic hormones
(PGF2α)
5

6. Biochemical Structures
• Peptides (GnRH, Prolactin,
Relaxin, Oxytocin)
• Glycoprotein (FSH, LH,
Inhibin, Activin, follistatin)
• Steroids: (Testosterone, P4,
E2)
• Prostaglandins: (PGF2α,
PGE2)
6

7. Biosynthesis
of
Steroid
Hormones
From
Cholesterol:
Simple
view
7
27 carbons
21 carbons
21 carbons
19 carbons
18 carbons
Cytochrome P450
3β-hydroxysteroid
dehydrogenase & isomerase
17β-hydroxysteroid
dehydrogenase
P450 aromatase

8. 8
Hormon
e
Male Target
Tissue
Primary
Action in Male
Female
Target Tissue
Primary Action
in Female
GnRH Gonadotroph
Release of FSH
and LH
Anterior pituitary
Release of FSH and
LH
LH Lydig cells
Testosterone
production
Theca interna and
luteal cells
Ovulation, CL
formation,
FSH Sertoli cells
Sertoli cell
function
Granulosa cells
Follicle
development and
E2 production
Prolactin
Testis and
brain
Induce
maternal
behavior
Mammary cells
Lactation and
maternal behavior
Oxytocin
Epididymis,
vas deferens,
ampulla
PGF2a
synthesis and
sperm
movement
Myometrium and
myoepithlium of
mammary gland
Uterine motility and
milk ejection
Estradiol Brain Sexual behavior
Hypothalamus, all
reproductive tract,
mammary gland
Sexual behavior,
GnRH surge,
secretory activity of
tract, uterine
motility, mammary
gland development

9. 9
Hormone Male target
tissue
Primary action
in male
female
target
tissue
Primary
action in
female
Progesteron
e
----- -----
Endo- and
myometrium,
mammary
gland,
hypothalamus
Endometrium
secretion,
inhibit
GnRH release
No reproductive
behavior,
pregnancy
Testosterone
Accessory sex
glands, tunica
dartos,
seminiferous
epithelium
Anabolic growth,
spermatogenesis,
secretion of
accessory
sex glands
Brain, skeletal
muscle,
granulosa cells
Substrate for E2
synthesis,
abnormal
masculinization
PGF2a
Epididymis epididymal
contractions
Corpus luteum,
uterine
myometrium,
ovulatory
follicles
Luteolysis,
uterine
contraction,
ovulation

10. 10
Hormone Male target
tissue
Primary action in
male
female target
tissue
Primary action in
female
Relaxin
Sperm and
male tract
Sperm motility
Pelvic ligaments,
cervix,
mammary gland,
nipples
Softening of pelvic
ligaments,
cervix, connective
tissue remodeling
hCG
----- -----
Ovary
Progesterone
production
eCG
----- -----
Ovary
Accessory CL
formation
Placental
lactogen
----- ----- Mammary gland of
dam
----- -----

11. 11