Structure and ultrastructure of the epididymis of the viviparous lizard during the annual hormonal cycle: Changes of the epithelium related to secretory activity

Abstract

This study deals with the structure and ultrastructure of the epithelial cells of the lizard (Lacerta vivipara Jacquin) epididymis as related to secretory activity. The epithelium contains only two types of cells, secretory cells and basal cells. The secretory cells undergo an annual cycle which has been divided into 10 stages. In its most active secretory state, epithelium forms 65.3% of the organ volume. The secretory cell is a tall columnar cell (from 55 ± 3.4 μm to 74.3 ± 2.4 μm height) with a basal nucleus and a supranuclear cytoplasm almost entirely occupied by numerous large secretory granules (5 to 7 μm in diameter). At the ultrastructural level, secretory cells contain rough endoplasmic reticulum (RER), Golgi complex, and secretory granules at various stages of synthesis before being discharged into the lumen. Each granule is membrane-limited and contains a spherical electron dense central core and a peripheral vacuole which varies in density. The secretory cell originates from small cubic cells (13.8 ± 0.7 μm) with few organelles (stage 1). The height of the cell increases gradually and free ribosomes appear first (stage 2), followed by scarce elements of RER (stage 3). The step preceding the secretion period (stage 4) is characterized by a conspicuous increase in volume of RER and Golgi complex. From stage 7 to stage 10, the cell undergoes a dramatic involution. After a transient hypertrophy of the RER, numerous autophagic vacuoles invade the cytoplasm. This degeneration can lead to a complete lysis of the cell and to its rebuilding after elimination of the greatest part of the cytoplasm. The volume of the epithelium falls to 15.6% of the total volume. With antibodies raised against the protein family which constitutes the main part of the secretion (L proteins of 19 kDa), it is shown by immunohistochemistry that these proteins are concentrated into secretory granules which are discharged into the lumen to finally bind to the heads of the spermatozoa.

Proximal Testicular Ducts of the Mediterranean Gecko (Hemidactylus turcicus)

“…In the lizard Sitana ponticeriana these cell types and their localized presence suggests four main regions similar to mammals but the regions were not found in H. turcicus (this study) or the snake Seminatrix pygaea (Sever, 2010). Only two cell types, principal and basal cells, were present in the epididymis of H. turcicus, which is the same as noted for Lacerta vivipara (Mesure et al, 1991), Podarcis sicula (Desantis et al, 2002), and S. pygaea (Sever, 2010).…”

Seasonal changes in testicular and epididymal histology of the tropical lizard, Tropidurus itambere (Rodrigues, 1987), during its reproductive cycle

“…While Mesure et al (1991) affirmed that degeneration of the epididymis epithelial cells occurs in Lacerta vivipara during its reproductive cycle, this was not observed, even with transmission electron microscopy, in T. itambere.…”

“…Based on variations in epididymal maturation, Dufaure et al (1986) correlated cyclic development of the testis with that of the epididymis and its secretions. Mesure et al (1991) postulated a degenerative process leading to the destruction of the epithelium. However, the routine fixation methodology he used made confirmation of this impossible.…”

Morphological Changes of the Epididymis and Description of the Excurrent Ducts of Phrynops geoffroanus (Testudines: Chelidae) During the Reproductive Cycle

“…The epithelium is significantly higher during periods of reproductive activity. Cyclical alterations of epididymal ducts, as well as other ducts of the extratesticular seminiferous system, are influenced by the levels of sexual hormones, as observed in other species of reptiles (Mesure et al, 1991;Ferreira et al, 2002;Guerrero et al, 2004).…”