Morphological and ultrasonographic characterization of the three zones of supratesticular region of testicular artery in Assaf rams

Abstract

To fully understand the histological, morphometrical and heamodynamic variations of different supratesticular artery regions, 20 mature and healthy Assaf rams were examined through ultrasound and morphological studies. The testicular artery images of the spermatic cord as shown by B-mode analysis indicated a tortuous pattern along its course toward the testis, although it tends to be less tortuous close to the inguinal ring. Doppler velocimetric values showed a progressive decline in flow velocity, in addition to pulsatility and vessel resistivity when entering the testis, where there were significant differences in the Doppler indices and velocities among the different regions. The peak systolic velocity, pulsatility index and resistive index were higher in the proximal supratesticular artery region, followed by middle and distal ones, while the end diastolic velocity was higher in the distal supratesticular region. The total arterial blood flow and total arterial blood flow rate reported a progressive and significant increase along the testicular cord until entering the testis. Histological examination revealed presence of vasa vasorum in the tunica adventitia, with their diameter is higher in the proximal supratesticular zone than middle and distal ones. Morphometrically, the thickness of the supratesticular artery wall showed a significant decline downward toward the testis; meanwhile, the outer arterial diameter and inner luminal diameter displayed a significant increase distally. The expression of alpha smooth muscle actin and vimentin was higher in the tunica media of the proximal supratesticular artery zone than in middle and distal ones.

Anatomical and physiological adaptation of the scrotal artery with muscular reinforcement in the middle layer and connective reinforcement of the adventitia

“…The vascular wall with a double muscular layer would reduce the temperature as it passes into the scrotum, in the vicinity of the testis and seminiferous tubules. This function could corroborate the studies of Hassan et al (2022), who determined a significant presence of smooth musculature in the tunica media of scrotal arteries of rams that would regulate the progressive decrease in testicular blood flow. Classically, the anatomical variation (anatomical landmark) of the pampiniform plexus of the spermatic cord is usually mentioned as the temperature exchange area, where the descending artery yields heat to the ascending vein.…”

“…The vascular wall with a double muscular layer would reduce the temperature as it passes into the scrotum, in the vicinity of the testis and seminiferous tubules. This function could corroborate the studies ofHassan et al (2022), who determined a significant presence of smooth musculature in the tunica media of scrotal arteries of rams that would regulate the progressive decrease in testicular blood flow. Classically, the anatomical variation (anatomical landmark) of the pampiniform plexus of the spermatic cord is usually mentioned as the temperature exchange area, where the descending artery yields heat to the ascending vein.The findings described in this work indicate that possibly scrotal and testicular temperature regulation have other relevant histological factors and arrangements to fulfill and support this function, which should occur 2-3 C below body temperature (Alkhori & Barth, 2017), that physically protects and facilitates testis temperature regulation to F I G U R E 3 Microphotograph of the artery of the scrotal wall, with orcein staining; on the image on the left there is a general view.…”

An updated insight on testicular hemodynamics: Environmental, physiological, and technical perspectives in farm and companion animals

“…Previous studies reported decreases in the thickness of the artery wall and the vessel lumen as it enters the testis (de Souza et al 2014 ; Souza et al 2014 ). Similarly, a recent study in Assaf rams (Hassan et al 2022 ) reported morphological and hemodynamic changes in different regions of the STA. The study showed higher PSV, RI, and PI in the proximal region of the STA, followed by middle and distal ones.…”

“…Higher PSV, RI, and PI were found in the proximal region of the STA, followed by middle and distal ones. Also, significant progressive increases in the TABF and TABFR were found along the testicular cord until entering the testis Assaf rams Hassan et al 2022 Psychological status of the patient • Some animals such as dogs may experience tremors and fear, which can interfere with the Doppler examination Dogs Trautwein et al 2019 Diurnal effect • Diurnal rhythm induces significant changes in TBF over the 24 h a day Bucks Samir et al 2022 Abbreviations: TBF Testicular blood flow; PSV Peak systolic velocity; EDV End diastolic velocity; TAMAX Time average maximum velocity; RI Resistive index; PI Pulsatility index; TABF Total arterial blood flow; TABFR Total arterial blood flow rate …”

“…Considering the nonchange in the diameter of the examined vessel, as the values of RI and PI decrease, blood flow resistance reduces, and blood perfusion to the organ improves (Dickey 1997 ; Bollwein et al 2016 ). In general, blood flow pulsatility is higher in larger vessels as compared with smaller vessels (Hassan et al 2022 ). In small vessels, Doppler indices are mainly used to determine blood flow semiquantitatively, because it is often nearly impossible to accurately measure the diameter of small vessels (Blanco et al 2008 ).…”