The present work was carried out on 20 epididymes of sexually mature one humped camel to elucidate the gross anatomical, scanning electron microscopical and light microscopical features of the epididymal duct. Anatomically, the epididymal duct of camel consists of three parts i.e. head, body and tail. Histomorphologically, the epididymal duct is subdivided into initial, middle and terminal segments, of which the middle segment is further subdivided into proximal, intermediate and distal parts. The epithelium lining the epididymal duct is ciliated pseudostratified columnar comprising mainly five cell types, namely principal, basal, apical, dark and halo cells. It displays numerous intraepithelial glands in the middle segment. In general, there is a gradual increase in the total diameter and decrease in the epithelial height of the epididymal duct from the initial to the terminal segments; that may, mechanically, facilities passage of the sperms toward the terminal segment. The lamina propria of the epididymal duct contains a layer of interlacing elastic fibers which may allow adequate elasticity of the duct that could help in its expansion. Moreover it is surrounded by numerous layers of circularly and obliquely arranged smooth muscle fibers which always increase in thickness toward the terminal segment.
The camel is an important livestock species uniquely adapted to hot and arid environments. The primary uses of camels were for the transport of people in desert and semi desert areas [
The present work was carried out on 20 epididymes collected from mature clinically healthy camels (Camelus dromedarius). The materials were collected from Baniadie slaughter house in Assiut governorate. The materials were then preserved in 10% formalin and kept for further description.
Small pieces were taken from the three segments of the epididymal duct namely; initial, middle and terminal segments, fixed in mixture of paraformaldehyde solution (2.5%) and gluteraldehyde solution (2.5%) in phosphate buffer (pH 7.3) for 24 hours. The samples were washed in 0.1M phosphate buffer, dehydrated in graded ethanol, critical point-dried in liquid carbon dioxide, and then coated with gold palladius in sputtering device. The samples were then examined and photographed using JSM-5400LV Scanning electron microscope operated at 20 KV in the EM center of Assiut University.
The epididymal duct (immediately obtained after slaughtering) were divided into segments according to [
Small tissue blocks were taken from initial, middle and terminal segments of the epididymalduct fixed in paraformaldehyde-gluteraraldehyde solution in phosphate buffer [
(7.3 pH), then dehydrated in graded ethanol and embedded in epon-araldite mixture [
The epididymis consists of a highly convoluted duct which is tightly packed in a thick tunica albuginea. The tunica albuginea covering the epididymis is also covered by the visceral layer of the tunica vaginalis which become continuous with the parietal layer along the length of the epididymis. Anatomically the epididymal duct is composed of three distinct parts: the head, body and tail. The epididymal duct faces laterally along the dorsal border of the testis with the head curving around the cranial pole of the testis. It is attached to the head extremity of the testis by a fibrous band. The body of the epididymal duct is a thick flattened part attached to the dorsal border of the testis and forms a sinus that opens laterally. The tail is a small part attached to the tail extremity of the testis by the proper ligament of the testis and attached to the tunica vaginalis by the ligament of the tail of the epididymis. The epididymal duct is difficult to be visualized through the tunica albuginea particularly in the head and the body of the epididymis (
In cut sections, the epididymal duct is lined by long pseudostratified columnar epithelium arranged in the form of packed wheat stems (
protrusions and rounded secretory vesiclesare demonstrated in between and covering the stereocilia. The lumen of the epididymal duct shows collections of sperms in different segments. These collections are mainly seen in the middle segment (
The epididymal duct of the camel is divided into initial, middle and terminal segments. In addition, the middle
segment is further subdivided into proximal, intermediate and distal parts. The epididymal duct is lined by a pseudostratified ciliated columnar epithelium and surrounded by thin lamina propria and circular smooth muscular layer (muscular coat). The height of the epithelium varies between the different segments of the epididymial duct, the highest epithelium is seen in the initial segment and decreases gradually toward the terminal segment. The epithelium consists of five cell populations: principal, basal, apical dark and halo cells. The distribution of these cells varies in different epididymal segments. However, principal and basal cells are the most frequent cell types throughout the whole length of the epididymal duct (Figures 8-12).
The principal cells are long cylindrical, columnar cells extending from the basement membrane to the lumen. The nuclei of the principal cells are vesicular with evident one or two nucleoli. In the initial segment, these nuclei are oval, elongated in shape and basally located (
The basal cells are small oval to spherical cells with spherical, vesicular nuclei and lightly stained cytoplasm. They are located between the principal cells resting on the basement membrane. These cells are seen along the whole length of the epididymal duct but they increase gradually in number toward the terminal segment (Figures 10-12).
The apical cells are wedge or triangular in shape, with the apex facing basally and the base facing apically, they have rounded apically situated nuclei. These cells are located between the principal cells being more frequent in the initial segment, proximal and intermediate parts of the middle segment then decrease gradually in number toward the distal part of the middle segment until being very few or nearly absent in the terminal segment (Figures 8-12).
The dark cells are narrow, tall and darkly stained cells extending from the basement membrane to the lumen between the principal cells. They have dark, elongated fusiform nuclei. They are observed in all epididymal segments but they increase in frequency toward the terminal segment (Figures 10-12).
The hallo cells are rounded or irregular in shape with dark, small nuclei surrounded by a light halo of pale cytoplasm. They are observed throughout the epididymal duct variably distant from the basal lamina, but they mostly occupy a higher position in the initial segment (
Strongly PAS-positive granules may be demonstrated in the basal portion of the epithelium practically in principal cells (
open into the lumen of the epididymal duct (
The epididymis constitutes an important part of the male genital duct system. It plays key role in the maturation and storage of spermatozoa [
Anatomically and in agreement with previous studies [7,18] the epididymis of camel consists of three parts i.e. head, body and tail. The whole organ is covered by a thick tunica albuginea which do not allow the epididymal duct to be visualized grossly through it. Another reason for the latter statement could be attributed to the narrow epididymal duct as compared to some other domestic animals like bovines [
Recently the classic classification of the epididymis into head, body and tail has been found to be unsatisfactory [
the epididymis is subdivided into initial, middle and terminal segments, of which the middle segment is further subdivided into proximal, intermediate and distal parts. The histological and histochemical characteristics of different epididymal segments include regional variations in the total diameter, epithelial height, morphology and distribution of different cells, length of stereocilia, and thickness of the elastic fibers in the lamina propria as well as thickness of the muscular coat. [
The current study supports the previous findings in different species including camel concerning the gradual decrease in the epithelial height of the epididymal duct from the initial through middle to the terminal segments [7,18,19,23-26]. This gradual decrease in the epithelial height distalwards the epididymal duct may mechanically facilities passage of the sperms toward the terminal segment. High epithelium in the initial segment may, however indicate a more absorptive power of the epithelium in this segment. In this respect, [
The epithelial lining the epididymal duct is ciliated pseudostratified columnar comprising mainly five cell types, namely principal, basal, apical, dark and halo cells. These findings simulate previous observations in the camel [18,35]. Among the above mentioned cells, the basal cells are characterized by high nuclear: cytoplasmic ratio [
In agreement with [19,23-25], the principal cells are the major cell types of the epididymal epithelium. The nuclei of these cells in the initial segment are elongated oval in shape and basally located, but in the middle segment they are rounded and found at higher levels but not at one line. In the terminal segment the nuclei are small, darkly stained and densely arranged; they seem to form one row just above the level of basal cells. The latter observation could be due to enormous widening of the epididymal duct in this segment. Unlike observations of [
Light microscopically, the apical cells of the camel epididymis share many characteristics of adjacent principal cells concerning their nuclear and cytoplasmic pictures. These results are consistent with those of [
In agreement with [
The lamina propria of the epididymal duct, as demonstrated in the present study, contains a layer of interlacing elastic fibers which becomes thicker toward the terminal epididymal segment. These elastic fibers may allow adequate elasticity of the duct that could help in its expansion. Moreover, the lamina propria is surrounded by numerous layers of circularly and obliquely arranged smooth muscle fibers which always increase in thickness toward the terminal segment. This comes in agreement with previous studies in different species including camel [18,23-25]. These authors have also added that, the periductular smooth muscle along the length of the epididymal duct may play an important role in the passage of the sperms toward the terminal segment. [
PAS positive granules are demonstrated in different segments of the epididymal duct. The intraepithelial glands are full of PAS positive material. The PAS positivity gives evidence for the presence of glycoprotein in relation to a secretory product [