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Myelinated fibers  and axons distribution in phrenic nerve of male and female wistar- kyoto (WKY) and spontaneously hypertensive rats (SHR)

Anaceres Ribeiro Rodrigues1, Renata da Silva Ferreira1, Helio Cesar Salgado2, Carlos Augusto Carvalho de Vasconcelos3, Valéria Paula Sassoli Fazan1*                                                                                                    

Abstract

Histological examination of the diaphragm showed gender differences in fiber composition but gender differences on phrenic nerve myelinated fiber morphometry were  not thoroughly addressed. A descriptive morphologic and  morphometric study of the phrenic nerves in male and  female SHR and  WKY was recently published but the myelinated fiber morphometry needs  further exploration. After arterial pressure and  heart  rate recordings, phrenic nerves of young adult (20  week-old) male and  female SHR and  WKY were prepared for epoxy resin embedding  and light microscopy. Morphometric analysis was performed with the aid of computer software, with special attention to myelinated fiber and their respective axons area  and diameter. Our results showed for male and  female SHR remarkable longitudinal asymmetry on both sides and  an asymmetry between  sides on distal segments, which were not present on WKY nerves. There may be significant differences also in other species, as well as asymmetry of the motor and sensory nerves in diabetic rats induced by STZ@ and malnourished rats with

8% protein in the diet during pregnancy until weaning,  or both pathological conditions, where the malnourished- diabetic  animal could intensify these results corroborating  the understanding  of nutritional factors influencing cardiovascular and neural physiology of individuals with chronic degenerative  diseases.