La histología regional del conducto del epidídimo en el perro comprende cinco regiones histológicamente distintas y continuas. Dos de las. Test Histologia aparato reprodutor epididimoenEpididimo Cual epitelio presenta el Epididimo?. Cuales fibras que rodean?. Cual epitélio. Histology and testicular and epididimal ultraestructure in Anolis sagrei (Sauria: Polychrotidae)/Histologia y ultraestructura testicular y del epididimo de Anolis.

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The epididymis of the dog, based on morphological differences, reveals five distinct and continuous zone in the duct.

It is observed zone I and zone II, both of them localized into the head. The third zone, or zone III, comprises the distal head and all the body. The fourth and fifth zones zones IV and Vare restricted to the tail, localized into the proximal and distal Cauda epididymidis, respectively. Each zone can be readly distinguished on the basis of its own duct morphological characteristics.

This distinction concerns epidicimo to the overall duct histology, and also to cytological appearence and epithelial lining constitution. The mammalian epididymidis is an important segment of the excurrent duct system of the testis, that performs a variety of functions.

HAMILTON reported that epididymis is a dynamic structure of the seminal pathway, and its complex epidivimo does not agree with the concept that epididymis would have merely a passive influence on sperm physiology. An immunocytochemical study reveals histolpgia expression patterns of several cytokeratins, vimentin and desmin in the epididymis of the dog WAKUI et al.

Despite such studies, stressing the importance of the morphofunctional knowledge of the dog epididymidis, little information is available on the regional histology of the duct ORSI, Thus, the purpose of this study is to describe morphologically the regional histology of the ductus epididymidis in the dog, epiddidimo provide a detailed structural baseline for specific studies of functional zonation in the epididymis of the dog, or, to comparate to other mammals.

Ten adult, mongrel, sexually mature dogs Canis familiarisL. The samples, collected from the anatomical regions of the epididymides, were histllogia in Bouin’s fluid, dehydrated and embedded in paraffin. The tissues were observed in a Olympus BH-2 microscope. The rounded tubules, obtained from several sections of different epididymal regions, were measured for height of epithelium, diameter of lumen and thickness of muscle coat. From the average values for each animal and its distinct epididymal zones, arithmetic means and s.

The epjdidimo in the dog, reveals five distinct and continuous histological zones in the duct. It is observed zone I or initial segment and zone II, both of them epidicimo into the head.

The zone III comprises the distal head and all the epididymal body. The fourth and fifth zones zones IV and Vare restricted to the epididymal tail, localized into the proximal and distal Cauda epididymidis, respectively.

The last region Vis continuous to the vas deferens Fig. The entire epididymal duct has a similar histological appearance, showing a pseudostratified epithelial lining, with stereocilia, covered by a myo-connective tissue sheath. However, each epididymal region shows differentiating features with respect to epithelial height, luminal diameter, thickness of muscular wall, and cytological characteristics of epithelial cells.

Also, it should be noted that transition histoloyia the zones is gradual, not abrupt. Hence, there is always an overlapping of morphological characteristics between histolgoia adjacent regions.


Along the five regions in dog epididymidis, are found columnar cells and basal cells. Two different types of columnar cells could be distinguished: The P cells epidiimo observed in all the five zones, of the epididymal duct. They are tall cells, which extend from the basal lamina to the lumen. The position and shape of their nuclei epidodimo variable, along the length of the duct Figs. The basal B cells lie next to the basal lamina, and do not reach the histolofia lumen.

The A cells had a slender shape, and are characterized by a wide cytoplasmic apical part, a narrow epidldimo and a more apically located nucleus, comparatively to P cells morphology.

The regional morphometric differences observed in epithelial height, luminal diameter and muscle-wall thickness, in all the histological zones, are summarized in Table I. The zone I or initial segmentis characterized by an irregular and tall epithelium The epithelium contained all the cell types noticed. The tall columnar Histolobia cells have round to spherical nuclei with one histokogia two distinct nucleoli, and usually the nuclei are localized in the lower half of the cells.

The cell boundaries are indistinct, and a large number of long stereocilia projects from histo,ogia apical cell surfaces to the lumen. B cells are seen in great number with ovoid nuclei and evident nucleoli. These cells are arranged in a distinct layer, disposed immediately over the basal lamina.

The A cells are fewer in number than the other cell types, and can be distinguished from P cells by their slender globlet shape, and apically located nuclei. The irregular lumen of the ductus have a diameter of The duct is histloogia by a smooth muscle layer of about The epithelial height of zone II is somewhat lower than those of zone I The adluminal stereocilia are long. A cells in zone II are similar, in appearance, to those found in the initial segment.

The B cells are characterized by presence of nuclei of different shapes. The epididymal lumen in zone II appears regular, and contains rather immature spermatozoa in scarce number, and also cellular remnants. The muscular coat, surrounding the duct, almost does not vary in thickness Some features distinguished the epithelial lining of zone III. The epithelium decreases in height and, concomitantly there is an increase in luminal diameter and in muscle wall thickness. This zone was characterized by irregular epithelium The epithelium contained the same three cell types, similar to other zones.

Histologia aparato reprodutor epididimo

P cells were the major cell type, and possessed slightly shorter; irregular stereocilia, with ovoid and elongated nuclei located at the middle part of the cells. A cells, with round to ovoid nuclei, are scarcely found, and B cells are similar to those of preceeding zones. The luminal diameter has average of P cells have round nuclei, with one or two evident nucleoli; stereocilia are regular and shorter forming a brush border.

The relative number of B and A cells is less frequent than in previous histological zones, and none peculiar features in both cells were seen, comparatively to those in other zones. The muscle coat surrounding the epididymal duct in zone IV Figs.

Several histological features differentiate the zone V from the other epididymal zones, in the dog. Thus, the zone V was characterized by lower epithelium, greater luminal diameter, greater sperm concentration, denser and shorter stereocilia, and a thicker smooth-muscle wall, comparatively to other epididymal zones.


The epithelial lining measures P cells are also the most common epithelial cell type found in this zone.

Usually, their nuclei are round and situated at the middle part of the cell but, because of the shortness of the P cells, nuclei rest near the basement membrane. The stereocilia still are regular and shorter, forming a brush border. The few B cells found, contained an elongated nucleus parallel to the basal lamina.

A cells are scarce and presented the same morphology, as described later. The luminal diameter is The jistologia occurrence of many packets of spermatozoa is a typical feature of this zone. The muscle coat is thicker The epididymis, in all epidiidimo species studied, so far is known, present variabilities in structure and function along its length. Based upon morphological features such as: However, in this histklogia the zone II is restricted to the head of the dog epididymidis exclusively.

Thus, the middle segment of the dog epididymidis, or zone III, comprises the distal head and all the body.

Previously, ORSI et al. The zone V comprises the distal tail, and is characterized by lower epithelial lining, greater luminal diameter, shorter stereocilia, packed spermatozoa inside the tubular lumen, and a thicker smooth muscle wall, comparatively to the other histological zones in the dog epididymidis.

The epithelial lining of all histological zones in the dog epididymidis contains, mainly, three cell types: In contrast to those findings, in our present study, it has been found A cells histilogia all the histological zones of the dog epididymidis, although in the zone V distal tailthey are not so striking, owing spididimo the lower epithelial height.

Fully exposed epididymis of histologiq dog. Note the anatomical regions: Initial segment zone I. Note the principal papical a and basal b cells, and the stroma periductal rose.

Estructura del estroma conjuntivo del epididimo del bovino cebu (Bos indicus)

Epithelium of zone II showing p, a, and b cells, stereocilia s and stroma periductal rose. Epithelium of zone IV showing p and b cells. Note the stereocilia s and myoepithelial cells arrowheads. On the regional histolohia of the ductus epididymis in the buffalo Bubalus bubalis.

Development of the fertilizing ability of spermatozoa in the epididymis of the rabbit. Maturation, transport and fate of spermatozoa in the epididymis. Regional distribution of steroids in the dog epididymis. A morphologic study of the ductus of the epididymis of Sus domesticus. Histochemical localization hostologia carbonic anhydrase in the testis and epididymis of the boar. Ultrastructural differences in efferent ducts and several regions of the epididymis of the hamster.

Some aspects of structure and function in the mammalian epididymis. Morphology of the bovine epididymis. Regional differences in the morphology of the goat epididymis: A light microscope and ultrastructural study. Studies epifidimo the guinea pig epididymis. Ultrastructure and quantitative morphology of the principal cells. Structure and function of the epithelium lining the ductuli efferentes; ductus epididymis histo,ogia ductus deferens in the rat.

The structure of the epididymis, efferent ductules and ductus deferens in the guinea pig: