Microvasculature of the buffalo epididymis

Abstract

The microvasculature of the water buffalo (Bubalus bubalis) epididymis was investigated using light (LM), scanning electron (SEM), and transmission electron (TEM) microscopy techniques. SEM analysis of the buffalo epididymis showed fenestrations that occupied ovoid inside the endothelium of the postcapillary venules located in the caput, corpus, and cauda. They varied in shape and dimension, but more importantly, they connected the venules of the blood vascular system to the capillaries of the peripheral lymphatic vascular system. Morphofunctional analysis of these connections suggests that the microvasculature of the buffalo epididymis plays a role in facilitating the circulation of biologically active substances, and the absorption and secretion processes necessary for the survival and maturation of spermatozoa. The lymphatic capillaries at the connection points formed a network of variously sized polygonal links. These capillaries then converged to form the precollector lymphatic vessels, which in turn converged with the larger vessels originating from the testis. It was further noted that in the capillary endothelium there were no fenestrations, and in the large veins there were many diverticula. These diverticula appear to play a role in the regulation of the seasonal variations of the blood reflux. In general, the microvascular architecture of the buffalo epididymis, particularly its connection to the lymphatic vascular system, appears to play an important role in the absorption and secretion processes of the epididymal epithelium.

Pecten oculi of kestrel (Falco tinnunculus rupicolaeformes) and little owl (Athene noctua glaux): Scanning electron microscopy and histology with unique insights into SEM–EDX elemental analysis

“…The visual (diurnal or nocturnal) active clock hours with the different feeding lifestyles were related to the morphological, ultrastructural appearance and composition of the intra‐ocular pecten oculi as they appeared in the diurnal avian species. These findings suggest that the pecten oculi may play a crucial role in facilitating visual activity and feeding behavior in diurnal avian species, such as the omnivorous birds like the Garganey, Eurasian moorhen, common loon, and duck (Abumandour et al, 2021; Braekevelt, 1986; Scala et al, 2002); the carnivorous birds like the great horned owl (Braekevelt, 1994; Kiama et al, 1994; Rahman et al, 2010), red‐tailed hawk (Braekevelt, 1991b), common buzzard (Gültiken et al, 2012), seagull (Ince et al, 2017), black kite (Kiama et al, 1994), stork (Onuk, Tutuncu, Alan, Kabak, & Gezer, 2013), and sparrow hawk (Rajab, 2012); and the herbivorous birds like the budgerigar, quail, emu, ostrich, and sparrow (Braekevelt, 1998; Elghoul et al, 2022; Micali et al, 2012; Orhan et al, 2011; Rajab, 2012). But nocturnal birds were represented mainly by carnivorous birds such as the nighthawk (Braekevelt, 1984), common barn owl (Yilmaz et al, 2017), barred owl (Smith et al, 1996), and yellow‐legged gulls (Segovia et al, 2020).…”

“…Further studies could explore how these variations in pecten oculi structure contribute to differences in visual acuity and light sensitivity between kestrels and little owls. Table 2 discusses the substantial variations in the number of pecteneal pleats and shows that there were significantly fewer pecteneal pleats in the pecten oculi of the nocturnally visually active birds than in the diurnally visually active birds (Abumandour et al, 2021; Abumandour et al, 2022; Braekevelt, 1986, 1988; Braekevelt, 1990, 1991b; Braekevelt, 1994; Elghoul et al, 2022; Gültiken et al, 2012; Ince et al, 2017; Kandyle et al, 2022; Kiama et al, 1994; Kiama et al, 2001; Korkmaz et al, 2023; Micali et al, 2012; Onuk, Tutuncu, et al, 2013; Scala et al, 2002). The pecten oculi of the herbivorous diurnal visually active birds had a large number of pleats, in which there were 24–25 and 16–19 pleats in the ostrich, but with different habits and environmental conditions (Elghoul et al, 2022; Kiama et al, 2006); 22–24 pleats in the migratory Eurasian moorhen (Abumandour et al, 2021); 18–22 pleats in the quail, pigeon, and chicken (Orhan et al, 2011; Pourlis, 2013; Ramos Jr & Tingari, 1984); the only exception was the migratory European wild quail that possessed about 10–11 pleats (Abumandour et al, 2022).…”

“…According to certain theories, the melanocytes help hold the pecten firmly straight in the vitreous humor by acting as a structural support (Braekevelt, 1991b). Little lymphatic capillaries were observed in ducks, according to Corona et al (2004) andScala et al (2002), along with blood capillaries. According to Crozier and Wolf (1944), this pigment aids in visual precision; (King & McLelland, 1984) noted that it functions as a dark mirror by reducing glare and reflecting an image of an object approaching from the sun's direction onto the retina; (Frost & Mouritsen, 2006) hypothesized that it may aid in navigation.…”