Epididymis (ductus epididymidis)
Pritam S. Sahota, Robert H. Spaet, Philip Bentley, Zbigniew W. Wojcinski in The Illustrated Dictionary of Toxicologic Pathology and Safety Science, 2019
is a part of the integrated sperm transport system that includes the efferent ducts, initial segment, caput, corpus, cauda, and vas deferens. It is a highly coiled, tortuous duct which links the efferent ducts to the vas deferens. In rodents, the efferent ducts are long, thin, tortuous, and located within the epididymal fat pad. In the dog, they are collected with the initial segment of the epididymis. In cynomolgus monkeys, the efferent ducts share a connective tissue capsule with the head of the epididymis but are located slightly proximal and may be present in a routine epididymal section. The epididymis itself is relatively long and loosely attached to the testis in the rodent, whereas in man and other domestic animals it is comparatively shorter and attached more tightly. It is lined by pseudostratified, ciliated columnar epithelium, which is surrounded by loose connective tissue and smooth muscle cells. Periductal smooth muscle fibers increase in number toward the cauda, while epithelial height decreases toward the cauda. Cell types within the epididymal epithelium include principal cells with apical stereocilia (the primary cell type), basal cells, halo cells (a subset of T lymphocytes and monocytes), and clear cells. The epididymis serves several functions, including sperm maturation, protection, concentration, and storage. Spermatozoa are relatively immotile in the caput but transition to fully motile and capable of recognizing and fertilizing an oocyte in the cauda.
Regulation of Reproduction by Dopamine
Nira Ben-Jonathan in Dopamine, 2020
The male genital tract transports sperm from the site of production to the exterior of the body, provides storage capacity for the sperm and assists in its maturation. The epididymis is a coiled segment of the spermatic ducts that stores spermatozoa while they mature and then transports them to the vas deferens, which connects to the urethra. The epididymis is composed of a head (caput), body (corpus), and tail (cauda). A significant portion of sperm maturation (i.e., the acquisition of motility and fertility) is carried out in the caput, while storage occurs in the cauda. Final sperm maturation (capacitation) is completed within the female reproductive tract, as discussed later in this chapter. The ampulla of the vas deferens serves as an accessory storage site for sperm. Heightened sexual activity and frequent ejaculation can result in the appearance of immature and immotile sperm in the ejaculate. The vas deferens carries sperm from the epididymis to the ejaculatory ducts by peristalsis. During ejaculation, the sperm mixes with fluids from the seminal vesicles, prostate gland, and bulbourethral glands, which form the semen and provide an environment that promotes sperm survival and fertility. Semen contains only 10% sperm by volume, with the remainder consisting of the combined secretion of the accessory glands; seminal vesicles contribute about 60% of this fluid. The secretion of the seminal vesicles contains fructose (the main substrate for sperm glycolysis), ascorbic acid, and prostaglandins. Prostaglandins were first discovered in seminal fluid and were mistakenly considered the product of the prostate gland, and hence their name.
Ultrasonography of the Bovine Reproductive System: Ultrasound Management of the Male Reproductive System
Juan Carlos Gardón, Katy Satué in Biotechnologies Applied to Animal Reproduction, 2020
The tail of the epididymis is the most accessible part of the epididymis, located in the ventral part of the testicle with the typical conical shape (Gnemmi, 2007; Gnemmi and Lefebvre, 2009, 2010). The tail of the epididymis is visualized ultrasonographically by means of oblique transversal cuts. A small linear probe (TLine) produces excellent images thanks to the reduced contact surface of the probe itself. The tail of the epididymis seems less echogenic than the testicular parenchyma, but above all less homogeneous. It differs very well from the testicles (Fig. 3.4). In the spermatic cord, the presence of the pampiniform plexus is dominant, characterized by tortuous anechogenic ducts. Only through the use of color Doppler, it is possible to distinguish the arterial branches of the dense network of venous anastomosis, forming a part of the plexus.
Epididymal ultrastructural changes associated with chronic cholestasis after bile duct ligation in adult rats
Published in Ultrastructural Pathology, 2018
Yomna I. Mahmoud, Faten S. Abo-Zeid
Testicular atrophy and testesterone insufficiency have been commonly reported associated with chronic liver diseases. Though testosterone dependent, the epididymal changes induced by liver disease have never been studied before. Thus, this study aimed to assess the ultrastructural events in the epididymis of rats with chronic obstructive jaundice. Chronic cholestasis induced many epididymal structural alterations manifested by the reduced tubular diameters, thickening of the tubular basement membrane, and regression of the principal cells. This was accompanied with reduction of principal cell organelles, cytoplasmic vacuolations, nuclear alterations, and stereovilli loss. The results establish that chronic cholestasis causes epididymal structural changes due to androgen deficiency.
Histological study on the effect of aroclor 1254 on the epididymis of adult rats and the role of L-NAME administration
Published in Ultrastructural Pathology, 2017
Nehad F. Mazen, Rania A. Zidan
Introduction: Aroclor 1254, a commercial polychlorinated biphenyls (PCBs) mixture, was found to elicit various adverse effects on human health. Objectives: This study aimed to investigate the structural alterations in the epididymis induced by aroclor 1254, and to assess the possible protective role of L-NAME (NG-Nitro-L arginine methyl ester). Materials and methods: Thirty-five adult male albino rats were divided into three groups: control group (15 rats), equally subdivided into subgroup a; negative control group, subgroup b: received intraperitoneal corn oil (5 ml/kg/day), and subgroup c: received intraperitoneal L-NAME (10 mg/kg/day). Aroclor-treated group (10 rats): received aroclor 1254 (2 mg/kg/day, intraperitoneal), and aroclor + L-NAME-treated group (10 rats): received aroclor 1254 combined with L-NAME in the same previous regimen. After 30 days, blood samples were collected for hormonal assay. Specimens from the epididymis were prepared for histological study and assessment of sperm count. Results: Rats in aroclor-treated group revealed a significant reduction in serum testosterone level and sperm count, in comparison with the control group. The epididymal caput showed stratification and detachment of the epithelium with vacuoles, mitotic figures, and electron-dense bodies together with increased collagen fibers in the interstitium. In addition, a strong reaction of androgen receptors (ARs) was seen in the cytoplasm of epithelial and stromal cells. These effects were attenuated by L-NAME administration. Conclusion: Aroclor 1254 provoked morphological and functional changes in the epididymis of adult rats, which were attenuated by L-NAME administration.
Connexins and pannexins
Published in Spermatogenesis, 2011
Gap junctions and connexins are critical for coordinating cellular functions in complex epithelia. In recent years there has been increased interest in understanding the regulation and function of gap junctions in both the testis and epididymis. Studies in transgenic mice in which connexin 43 (Cx43) is mutated or is knocked down only in Sertoli cells have demonstrated the essential role of Cx43 in spermatogenesis and differentiation of Sertoli cells. In the epididymis developmental studies have shown a role for numerous connexins in the differentiation of epithelial cells and communication between the basal cells and both principal and clear cells. In both tissues several factors, such thyroid hormones and androgens, are important in regulating expression and function of connexins. Pannexins, which form cellular channels but are structurally similar to gap junction proteins, have been identified in both testis and epididymis and, in the epididymis, are regulated by androgens. The objective of this review is to summarize the advances that have been made on the role and regulation of connexins and pannexins in the testis and epididymis and their implication in spermatogenesis and sperm maturation.
Related Knowledge Centers
- Male Genitalia
- Spermatozoa
- Testis
- Scrotum
- Urethra
- Prostate
- Male Genital Organs