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Abstract
SUMMARY AND CONCLUSIONS
The present work was carried out on 20 testes and epididymis of sexually mature camel (about 5 in every season) to elucidate the gross anatomical, morphometerical, light microscopical and scanning electron microscopical features of the epididymis in different seasons.
Anatomically, 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 comparatively narrow epididymal duct to be visualized grossly through it. The efferent ductules are anatomically belonging to the head of the epididymis. Microscopically, the lining epithelium of efferent ductules ranges from simple columnar in the proximal segment to ciliated pseudostratified columnar in the intermediate segment which become more crowded in the distal one. The lining epithelial cells divided into two main types, ciliated and non ciliated. The non ciliated cell always shows variable number of vacuoles with fine granules on the outer boundary of these vacuoles. Along the length of the efferent ductules, the lumen appears devoid of sperms except few sperm collections near the connection with the epididymal duct.
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 total diameter of the epididymal duct show slight narrowing in the two short proximal and intermediate parts of the middle segment before rewidening again in the distal part of the middle segment and terminal segment. This narrowing may partly hinder the passage of sperms through the middle segment that prerequisite for a longer stay allowing completion of their maturation.
There is a gradual decrease in the epithelial height of the epididymal duct from the initial to the terminal segments. This gradual decrease in the epithelial height distal wards in the epididymal duct may mechanically facilities passage of the sperms toward the terminal segment. High epithelium in the initial segment may indicate a more absorptive power of the epithelium in this segment. In addition, the epididymal epithelium in the initial segment is supported by a long and branched stereocilia that decrease in length through the middle segment being very short forming brush border in the terminal segment. The stereocilia of the camel epididymis stains positive with PAS and Alcian blue.
The epithelium lining the epididymal duct is ciliated pseudostratified columnar comprising mainly five cell types, namely principal, basal, apical, dark and halo cells.
The basal cells have been suggested to be a stem cell of the epididymal epithelium. The principal cells are the major cell types of the epididymal epithelium. The nuclei of these cells in the terminal segment seem to form one row just above the level of basal cells. This could be due to enormous widening of the epididymal duct in this segment. The dark cells are observed in all epididymal segments but they increase in frequency toward the terminal segment. The apical cells share many characteristics of adjacent principal cells concerning their nuclear and cytoplasmic pictures. Apical cells could be actually principal cells mechanically insinuated between the apical portions of the principal cells.
The epididymal epithelium of the camel displays numerous intraepithelial glands in the middle segment. However these glands may be also demonstrated in the initial and terminal segments. The gland start as a collection of small spaces within the basal part of the epididymal epithelium which coalesce to form a large space encircled by the surrounding cells by time these space grow up and the surrounding cells facing the lumen attain flat form and latter on open into the lumen.
These glands are formed when secretion are accumulated in a basal position below the nuclei of the principal cells and fail to access the lumen.
The lamina propria of the epididymal duct contains a layer of interlacing elastic fiber which becomes thicker toward the terminal 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
Although the epididymis demonstrates sperms in its lumen in all seasons the camel show moderate seasonal reproductivety expressed by variations in the weight and volume of the epididymis, total diameter of the efferent ductules and epididymal duct, epithelial height, length of the stereocilia, thickness of the muscular coat and cellular distributions in different segments. The spring months (with increasing day light and temperate temperature) offer ideal circumstances for maximal reproductive activity in this species. Despite increasing light in summer months, their extreme temperature has a greater negative effect on fertility. Moreover, the improvement in temperature in autumn and winter months is accompanied by short day light which does not give better conditions for increased fertility. The highest weight and volume values of the epididymis are observed in spring (26.83, 25.66 respectively) and the lowest values are recorded in summer (18.50, 18.33 respectively).
The weight value is higher than the volume value only in spring. Higher weight value in spring may be attributed to increased intensity of the epididymis due to excessive sperms contents in epididymis.
The total diameter of either efferent ductules or epididymal duct is higher in spring with wider lumen and slightly low lining epithelium as compared to other seasons. The increase in the total and luminal diameter of both efferent ductules and epididymal duct in spring may facilities normal passage of the large number of sperms coming from the testis in this season. Slightly low epithelium in spring may indicate higher activity whereas the high epithelium in other seasons may indicate accumulation of secretions within the epithelium and decreased activity.
The cellular components of the epididymal epithelium of the camel display important morphological changes from season to another showing signs of increase activity during spring in comparison to decrease activity in other seasons.
Basal cells show a relative increase in number during winter, a sign of increased number of principal cells that may be needed for a wider epididymal diameter in the coming spring. In the same connection the camel epididymal duct shows inward folding during winter which prerequisite for the expected dilation during spring. This could be an indication of the build up and may be perquisite for the increase in the total diameter of the epididymal duct in spring.
The principal cells in spring demonstrate vesicular lightly stained oval nuclei indicating increased activity in comparison to the smaller darkly stained nuclei in other seasons, a sign of decreased activity. Moreover the dark cells which are increased in summer considered as a dying cells indicating a DROP in the activity of epididymal epithelium.
PAS positive granules are demonstrated in efferent ductules and different segments of the epididymal duct in different seasons. These granules are relatively more numerous in spring. The intraepithelial glands are full of PAS positive material in the same period. The epididymal epithelium displays accumulations of dense bodies in the principal cells in autumn.
The lamina propria surrounding the epididymal duct contains a layer of the elastic fibers which is very thick in winter, thick in spring and thin in other seasons. This increase in thickness of the elastic fibers in winter predispose for the increase in the total diameter of the epididymal duct in spring.
The muscular coat of the middle and terminal segments is the thickest in spring. The thick muscular coat in the terminal segment in spring may be helpful for powerful ejaculation.
It seem that, there is a build up of the activity of the epididymal epithelium during winter which reaches maximum level in spring then subsides in summer and autumn.