[MARMAM] New publication available: The follicle-sinus complex of the bottlenose dolphin (Tursiops truncatus). Functional anatomy and possible evolutional significance of its somato-sensory innervation

Tommaso Gerussi tommaso.gerussi at studenti.unipd.it
Wed Oct 28 10:10:17 PDT 2020

Dear MARMAM Readers,

On behalf of my co-authors, I am glad to announce the publication in early
view of the paper "The follicle-sinus complex of the bottlenose
dolphin (*Tursiops
truncatus*). Functional anatomy and possible evolutional significance of
its somato-sensory innervation" in the Journal of Anatomy.


Citation: Gerussi T, Graic J-M, De Vreese S, Grandis A, Tagliavia C, De
Silva M, Huggenberger S and Cozzi B.


Vibrissae are tactile hairs found mainly on the rostrum of most mammals.
The follicle, which is surrounded by a large venous sinus, is called
"follicle-sinus complex" (FSC). This complex is highly innervated by
somatosensitive fibers and reached by visceromotor fibers that innervate
the surrounding vessels. The surrounding striated muscles receive
somatomotor fibers from the facial nerve. The bottlenose dolphin (Tursiops
truncatus), a frequently described member of the delphinid family,
possesses this organ only in the postnatal period. However, information on
the function of the vibrissal complex in this latter species is scarce.
Recently, psychophysical experiments on the river-living Guiana dolphin
(Sotalia guianensis) revealed that the FSC could work as an electroreceptor
in murky waters. In the present study, we analyzed the morphology and
innervation of the FSC of newborn (n = 8) and adult (n = 3)
bottlenose dolphins. We used Masson's trichrome stain and antibodies
against neurofilament 200 kDa (NF 200), protein gene product (PGP 9.5),
substance P (SP), calcitonin gene-related peptide, and tyrosine hydroxylase
(TH) to characterize the FSC of the two age classes. Masson's trichrome
staining revealed a structure almost identical to that of terrestrial
mammals except for the fact that the FSC was occupied only by a venous
sinus and that the vibrissal shaft lied within the follicle. Immunostaining
for PGP 9.5 and NF 200 showed somatosensory fibers finishing high along the
follicle with Merkel nerve endings and free nerve endings. We also found
SP-positive fibers mostly in the surrounding blood vessels and TH both in
the vessels and in the mesenchymal sheath. The FSC of the bottlenose
dolphin, therefore, possesses a rich somatomotor innervation and a set of
peptidergic visceromotor fibers. This anatomical disposition suggests a
mechanoreceptor function in the newborns, possibly finalized to search for
the opening of the mother's nipples. In the adult, however, this
structure could change into a proprioceptive function in which the
vibrissal shaft could provide information on the degree of rotation of the
head. In the absence of psychophysical experiments in this species, the
hypothesis of electroreception cannot be rejected.

Thank you very much for reading it.

Best regards

*Tommaso Gerussi, DVM, PhD candidate*
Department of Comparative Biomedicine and Food Science - University of
Viale dell'università 16, 35020 Legnaro (PD)
+39 3343301409
t <jeanmarie.graic at unipd.it>ommaso.gerussi at studenti.unipd.it
tommaso.gerussi at phd.unipd.it
Skype: tommaso.gerussi
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