Mammalian pheromones, including those of humans, occur in four varieties, primer, releaser, signaler, and modulator, which, respectively, affect endocrine responses, elicit behavior, provide information, and influence emotion.Pheromones assist in reproduction, feeding, social interactions and maternal-neonatal bonding in mammals. By definition and according to evolutionary theory, pheromones work within a species. Some chemicals operate between species

1. University of Chakwal, Pakistan

2. Topic: Types of Pheromones in Mammals and
their Functions
Department of Zoology
Presented by: Hina Mubashar
Roll no# UOC-BSZOL-F2020/020
BS Zoology
Session: 2020-2024
Course Title: Endocrinology
Instructor Name: Dr. Syeda Nadia Ahmad

3.  Introductoion
❑Introduction
❑Chemical nature
❑Types
❑Production
❑Detection
❑Functions

4. Introduction
▪ All animals have to coordinate their activity with other members of
their species. This requires some form of communication, which
involves the use of chemical signals, known as pheromones.
▪ Karlson and Luscher (1959) initially proposed the term
pheromones.
▪ They defined pheromones as “substances secreted to the outside of
an individual and received by a second individual of the same
species in which they release a specific reaction, for example, a
definite behavior or developmental process.”
▪ The term pheromone is usually reserved for chemical signals that
are produced and received by members of the same species, in
which both the sender and receiver of the signal gain benefit (Wyatt
2003).

5. Chemical Nature of Pheromones
 Organic compounds:
Pheromones are organic compounds made up of carbon, hydrogen and oxygen.
They are small and simple in structure.
 Structural specificity:
Their chemical structure varies greatly among species. For example insects
pheromones can be composed of hydrocarbons, whereas, mammalian
pheromones might include steroids or amino acids derivatives.
 Size and polarity:
Important features of chemicals used as pheromonal signals are their size and
polarity, which determine their volatility in air and solubility in water.
 Volatility:
Pheromones are volatile, allowing them to disperse through air and transmit
signals over distances. This volatility is essential for long range communication
within a species (Carde, R. T., & Haynes, K. F. 2004)

6. Pheromones Production
Animals use different mechanisms for releasing pheromones into
the environment.
In many cases, pheromonal release use existing routes for
excretion, such as urine and feces. For instance, the urine marks
used by rodents.
Other routes of pheromone release involve biological secretions.
Hamsters release the sexual attractant protein, aphrodisin, in their
vaginal secretions.
Most species of carnivore have anal glands, which produce
pheromones.

7. Pheromones Production
The rabbit mammary pheromone is
produced by glands around the nipples and
is present in rabbit milk.
Several potential chemosignals have been
identified in the saliva of different species.
Other specialized scent glands include
chin glands, interdigital glands and sternal
glands. (Brennan, P.A. 2010). https://assignmentpoint.com/wpc
ontent/uploads/2017/06/Pheromo
ne-0.jpg

8. Releaser
Pheromones
Primer
Pheromones
Signaler
Pheromones
Modulator
Pheromones
Pheromones
Types

9. Types of Pheromones
1. Releaser pheromones:
These elicit an immediate response
the response is rapid and reliable.
They are usually linked to sexual attraction.
2. Signaler pheromones:
These provide information.
They may help the mother to recognize her newborn by scent.
Signaler pheromones give out our genetic odor print.

10. Types of Pheromones
3. Primer pheromones:
These take longer to get a response.
They can influence the development or reproduction physiology,
including menstrual cycles in females, puberty, and the success or
failure of pregnancy.
In some mammals, scientists found that females who had become
pregnant and were exposed to primer pheromones from another
male could spontaneously abort the fetus.

11. Types of Pheromones
4. Modulator pheromones:
They can either alter or synchronize bodily functions.
They are usually found in sweat.
In animal experiments, scientists found that when placed on
the upper lip of females, they became less tense and more
relaxed.
Modulator hormones may also affect a female’s monthly
cycle.
(http://www.medicalnewstoday.com/articles/232635)

12. Mammalian Pheromones
Proboscidea
 Asian and African elephants investigated for their
pheromonal responses by the late Bets Rasmussen.
 During musth, elephants produce large quantities of a
specific pheromone, frontalin, that is released in
temporal gland secretions, urine, and breath.
 Adult males are mostly indifferent to frontalin,
whereas subadult males are highly reactive.
 Female chemosensory responses to frontalin vary with
the hormonal status.
 Female Asian elephants excrete a urinary pheromone,
to signal to males their readiness to mate.
Figure: Musth condition
https://brill.com/view/journals/b
eh/159/3-4/article-p207_1.xml

13. Marsupialia
In marsupials, the gray short-tailed
opossum (Monodelphis domestica)
communicates by scent marking.
The male opossum possesses a
prominent suprasternal scent gland,
whose extracts strongly attract
female opossums
Stimulating the estrus in anestrous
females via the vomeronasal system. Figure: Grey short-tailed opossum
https://www.researchgate.net/figure/The-
Grey-Short-tailed-Opossum-
Monodelphis-domestica-A-Opossum-
pups-at-P7-attached-to_fig12_51786664

14. Primata
 Primates rely on chemical communication
 The ring-tailed lemur (Lemur catta) exhibits
the highly developed olfactory system.
 Lemur catta possesses scent glands and a
variety of scent-marking displays.
 Both sexes have apocrine, located on the
wrists, and sebaceous gland fields in their
genital regions.
 Males mix the glandular secretions and then
deposit this mixture via “wrist marking.”
Figure: Ring-tailed lemur
https://lemur.duke.edu/discover/
meet-the-lemurs/ring-tailed-
lemur/

15. Soricomorpha (Insectivores)
In tree shrew (Tupaia belangeri),
Both males and females mark their
surroundings with urine and skin
gland secretions.
Males mark more frequently than
females.
Male scent stimulates marking in
females.
Interestingly, increasing amounts of
male scent result in a corresponding
increase in marking by females.
Figure: Tree shrew
https://www.pinterest.com/pin/co
mmon-treeshrew-tupaia-glis--
416231190537645906/

16. Carnivora and Ungulata
 Both carnivores (dogs and cats) and ungulates
commonly mark their territory with urine and
display a specific behavior called “flehmen”.
 In the flehmen reaction, animals, after the physical
contact, lift the head, draw back their lips, and
push the tongue towards the anterior region of the
palate.
 This attitude would allow a faster transfer of
pheromones into the olfactory organs.
 The saliva of the adult male pig contains a mixture
of steroids (boar odor).
 When a boar becomes aggressive or sexually
aroused, it produces copious amount of saliva
whose pungent odor is attractive to estrus females.
 The major component of the boar odor is
androstenone (Tirindelli, et.al,).
Figure: Flehmen reaction
https://www.boarbetter.com/en/t
he-importance-of-odour/

17. Pheromones in Humans
Pheromones in humans may be present in bodily secretions such as
urine, semen or vaginal secretions, breast milk and potentially also
saliva and breath.
Yet most attention thus far has been directed toward axillary sweat.
The axillary secretions originate from the highly dense eccrine and
apocrine (which secrete into hair follicles) sweat glands and
sebaceous glands.
The secretions are odorless but apocrine sweat acquires odor after
interaction with the cutaneous bacterial microflora.

18. Pheromones in Humans
Odor dispersal is modulated by several factors including
Clothing layers
Axillary temperature
Total hair surface
Arm movements
The main components of sweat are
Simple organic acids (eg, e-3-methyl-2-hexenoic acid and
3-methyl3-hydroxylhexanoic acid) (Hays, 2003).

19. Chemosensory Systems Detecting Pheromones
• responsible for recognizing
conventional volatile
odorant molecules
Olfactory
system
• used for sensing
pheromones
Vomeronasal
system

20. Vomeronasal Epithelium
The vomeronasal epithelium is part of the
vomeronasal organ (VNO) of Jacobson.
A tubular structure encased in a protective bony
capsule
Located at the base of the nasal septum.
The vomeronasal epithelium cannot be reached
by the airstream that regularly flows through the
nasal cavity.
Blood vessels and sinuses induces vasodilation
and vasoconstriction, producing a pumplike
action for stimulus access to the lumen.
Figure: Sensory system
https://tiesalesm.live/produ
ct_details/27246876.html

21. Vomeronasal Epithelium
In ungulates, the “flehmen” behavior is thought to be associated with
promoting stimulus access to the vomeronasal organ.
In the mouse, the vomeronasal sensory epithelium increases from birth
to puberty and becomes completely active at 2 months after birth.
Do human have a vomeronasal organ?
Vomeronasal organ is present in human embryos, contain bipolar
neurons.
The vomeronasal structure becomes more simplified later in
development.
Several reports showed that in human adults it becomes a blind-ended
diverticulum in the septal mucosa.

22. Olfactory Epithelium
The olfactory epithelium is the largest olfactory structure in mice,
containing millions of sensory neurons
detect airborne odorants and pheromones that enter the nasal cavity
through the nostrils.
detecting odorants at specialized cilia that contain the requisite receptors
and signaling components.
Olfactory sensory neurons enter the brain, where they form synaptic
connections in the olfactory bulb.
The architecture of the olfactory epithelium is particularly conducive for
detecting volatile odors.

23. Olfactory Epithelium
In mouse, the olfactory system is functionally
established during the prenatal phase.
The first axons contact the telencephalic vesicle
around embryonic day 13.
Conversely, axonal targeting to specific domains
within the main olfactory bulb occurs as early as
embryonic day 15.5. Figure: Olfactory Epithelium
https://www.sciencedirect.com/science/arti
cle/pii/S0896627305003922

24. Functions
Pheromones across different species perform certain
functions that acts as triggers or cues to responses
from other members of the same species:
 Sexual arousal trigger
 Raising the alarm
 Warning system
 Territory marking
 Bonding hormone
 Food trial marker
 Use to communicate
 Recognition between mother and offspring
Figure: Bonding hormones
https://www.123rf.com/photo_6281955
0_smiling-mother-and-father-holding-
their-newborn-baby-daughter-at-
home.html

25. References
 Brennan, P. A. (2010). Pheromones and mammalian behavior. The
neurobiology of olfaction.
 Liberles, S. D. (2014). Mammalian pheromones. Annual review of
physiology.
 Zufall, F., & Leinders-Zufall, T. (2007). Mammalian pheromone
sensing. Current opinion in neurobiology.
 Tirindelli, R., Dibattista, M., Pifferi, S., & Menini, A. (2009). From
pheromones to behavior. Physiological reviews.
 Hays WST. Human pheromones: have they been demonstrated?
Behav Ecol Sociobiol 2003.