Dynamics of the seminal vesicle epithelium

Seasonal variations in the morphology of the seminal vesicles of the African straw-coloured fruit bat (Eidolon helvum)

The study investigated seasonal changes in the morphology of the seminal vesicles of Eidolon helvum in a typical African tropical environment. Seminal vesicles of forty-eight bats were examined during the early rainy, late rainy and peak dry seasons, using gross anatomical, histological and ultrastructural techniques. The interlobular connective tissue septa from the external capsule demarcated the glandular parenchyma into numerous lobules of tubulo-alveolar glands. A simple cuboidal epithelium of mono- or bi-nucleated cuboidal cells lined the glandular mucosa during the rainy season. This was replaced by a bistratified cuboidal epithelium, whose upper layer of cells showed evidence of degeneration, during the dry season. The PAS-positive secretory products appeared to be numerous during the rainy season, but few and clumped together during the dry season. The mean gross weight, interlobular septal thickness, acini diameter and epithelial height of the glands varied significantly with season. Ultrastructural features of the secretory cells during the rainy season showed well-developed cytoplasmic organelles, numerous electron lucid secretory vesicles and electron-dense granules. Secretory epithelial cells of the seminal vesicles are very active during the rainy season, while regeneration of degenerated epithelium in preparation for the next reproductive cycle occurs during the dry season.

Histology, ultrastructure, and seasonal variations in the bulbourethral gland of the African straw-colored fruit bat Eidolon helvum

We studied the morphological characteristics and seasonal changes of the bulbourethral gland of Eidolon helvum in a typical African tropical environment. Forty-eight bulbourethral glands were examined using gross anatomical, histological, histochemical, and ultrastructural techniques during the early rainy, late rainy, and peak dry seasons. The pear-shaped bilateral bulbourethral glands were located extra-abdominally in the inguinal region. Trabeculae from the capsule divided the parenchyma into numerous lobules of tubuloalveolar glandular acini. The mucosa was covered by a simple columnar epithelium consisting up of principal secretory cells, columnar dense cells and basal cells, which were progressively pronounced during the dry season. The principal cells contained eosinophilic granules, which were PAS positive while the dense cells did not show affinity for the stains. The mean gross weights, acini diameters, and epithelial heights were greater during the rainy season than the dry season. Ultrastructural evaluation showed that the cytoplasm of the principal cells contained well-developed Golgi complexes, rough endoplasmic reticulum, mitochondria, and secretory vesicles of varying electron densities and sizes. The secretory vesicles were numerous during the early rainy season, decreased during the late rainy season and were scanty during the peak dry season. The simple columnar epithelium observed during the rainy season was replaced by an undefined stratified epithelium during the dry season, and this was associated with cellular degenerations and regenerations. In conclusion, E. helvum has a typical mammalian bulbourethral gland, with a unique cell type, the dense cell whose functions are not well-understood. The gland exhibits cyclical seasonal variation in structure and secretory activity; being active during the early rainy season (breeding season), and showing the lowest activity during the dry season (non-breeding season). Glandular epithelial cell renewal occurs during the dry season in preparation for the next breeding season.

Identification of a transcription factor, BHLHB8, involved in mouse seminal vesicle epithelium differentiation and function

The seminal vesicle is a male accessory sex organ that develops from segments of the Wolffian duct adjacent to the urogenital sinus. It produces most of the seminal plasma in both humans and rodents. To date, very few transcription factors have been linked to the development and differentiation of seminal vesicles. In this study, we have examined the role of basic helix-loop-helix (BHLH) B8 transcription factor expressed at high levels in the adult seminal vesicle and during seminal gland differentiation. Immunofluorescent studies indicate that BHLHB8 is expressed within the epithelial layer of the seminal layer of the seminal vesicle following branching morphogenesis but prior to full maturation of cell morphology and function. Analysis of mice that do not express BHLHB8 (Bhlhb8(-/-)) indicates no deficiency in the initial development of the seminal vesicle. However, morphological and ultrastructural analysis indicates disruption of the epithelial cellular architecture. The seminal vesicle epithelial layer of 2-mo-old Bhlhb8(-/-) mice shows extensive cellular degeneration based on the appearance of reduced microvilli, altered granule size, and dilated endoplasmic reticulum and Golgi apparatus. The seminal vesicle epithelial cells also degenerate prematurely, as evidenced by disruption of nuclear architecture and significant accumulations of autophagic bodies. These results identify BHLHB8 as a regulator in establishing and stabilizing the secreting epithelial cells of the seminal vesicle.

Structural and ultrastructural features of boar seminal vesicles

The morphological features of boar seminal vesicles were examined by light and transmission microscopy. Boar seminal vesicles consist of glandular tissue arranged in multiple lobules containing a system of ramified secretory tubules. The secretory tubules are composed of a mucosa formed by an epithelium and an underlying lamina propria and, are surrounded by a muscular layer. The epithelium is made up of columnar cells and occasional basal cells. Mast cells are frequently found among epithelial cells. Three types of columnar cells, considered different stages of the secretory cell cycle, are present: principal cells, clear cells and dense cells. Principal cells are functionally differentiated cells characterised by abundant mitochondria, great development of the rough endoplasmic reticulum and presence of secretory granules in their cytoplasm. The apical surface of many principal cells shows apical blebs filled with PAS-positive material. No acid mucosubstances are detected. Microvilli cover the apical surface except in the apical blebs. Dense cells, arranged between principal cells, are also functional differentiated cells but with signs of cellular degeneration. Clear cells are an initial differentiated stage of columnar cells and are characterised by the presence of a poorly developed rough endoplasmic reticulum and by the absence of secretory granules. Proliferating cells are present among columnar cells. Basal cells contain scarce cytoplasm, few organelles and no secretory granules. The lack of mitotic activity in these cells suggests that they do not act as precursors of columnar cells.

Differential progression of neonatal diethylstilbestrol-induced disruption of the hamster testis and seminal vesicle

The synthetic estrogen diethylstilbestrol (DES) is now recognized as the prototypical endocrine disruptor. Using a hamster experimental system, we performed a detailed temporal assessment of how neonatal DES-induced disruption progresses in the testis compared to the seminal vesicle. Both morphological and Western blot analyses confirmed that neonatal DES exposure alters androgen responsiveness in the male hamster reproductive tract. We also determined that the disruption phenomenon in the male hamster is manifest much earlier in the seminal vesicle than in the testis and that testis disruption often occurs differently between the pair of organs in a given animal. In the neonatally DES-exposed seminal vesicle, histopathological effects included: (1) general atrophy, (2) lack of exocrine products, (3) epithelial dysplasia, (4) altered organization of stromal cells and extracellular matrix, and (5) striking infiltration with polymorphonuclear leukocytes. Also, the morphological disruption phenomenon in the seminal vesicle was accompanied by a range of up-regulation and down-regulation responses in the whole organ levels of various proteins.

Effect of androgen concentration on seminal vesicle blood flow in rats—establishment of new highly sensitive simultaneous androgen measurement method

OBJECTIVES

To clarify the effect of androgen concentration on blood flow regulation in seminal vesicles and to identify the androgen most responsible for this effect.

METHODS

The androgen concentrations in the seminal vesicles and the seminal vesicle blood flow were measured at 0, 3, 6, 12, 24, 48, and 72 hours after castration. The androgen concentration was measured with a newly developed highly sensitive simultaneous androgen quantification method that uses liquid chromatography-tandem mass spectrometry. The blood flow was measured with the radioactive microsphere injection method. The change in seminal vesicle blood flow in 6-hour castrated rats after administration of 3 mg/kg testosterone, 3 mg/kg dihydrotestosterone (DHT), 3 mg/kg dehydroepiandrosterone, or 3 mg/kg testosterone plus 20 mg/kg finasteride was evaluated.

RESULTS

A correlation was observed between the DHT concentration and blood flow in the rat seminal vesicle after castration. The DHT concentration and blood flow decreased after castration to 31.6% and 37.9%, respectively, of the normal level at 6 hours. The decline in DHT concentration and blood flow decreased further thereafter to 2.2% and 18.1%, respectively, of the normal level at 72 hours. Both testosterone and DHT fully restored the organ blood flow in castrated rat seminal vesicles. However, the blood-flow-increasing effect of testosterone was attenuated by more than 50% when administered in combination with finasteride. Dehydroepiandrosterone did not increase seminal vesicle blood flow.

CONCLUSIONS

The results of our study showed a strong correlation between the organ DHT concentration and blood flow in rat seminal vesicles. Of the various androgens, the most active androgen in the regulation of seminal vesicle blood flow was DHT.

Role of Androgen on Blood Flow and Capillary Structure in Rat Seminal Vesicles

To clarify the effect of androgen on the microcirculation in seminal vesicles of adult Wistar rats, we investigated the organ blood flow and morphological features in the capillaries after castration and subsequent testosterone supplementation. Testosterone (T) was subcutaneously injected every 12 hours after castration and its doses were set to 10(-2), 10(-1), 10(0) and 10(1) mg/kg-body weight (T10(-2), T10(-1), T10(0) and T10(1) groups, respectively). Organ blood flow was measured using laser Doppler flowmetry, and the subepithelial capillaries were analyzed using transmission electron microscopy. The capillaries were morphologically classified into 3 types; oval opened (type 1), intermediate (type 2) and collapsed (type 3), and their luminal areas were measured using a computed image analyzer. The organ blood flow was significantly reduced from 36.3+/-5.1 to 21.9+/-2.7 ml x min(-1)/100 g tissue, and the luminal area of the capillaries was significantly reduced from 9.02+/-1.28 to 4.85+/-0.82 microm2 with the shift of the type 1 and type 2 to type 3 after castration. The reduction of the luminal area and the blood flow reduction, and shift of the capillary type were significantly protected by gradated testosterone supplementation. These results indicate that the maintenance of the blood flow and morphological profiles in capillaries depend on androgen-supplementation levels in seminal vesicles.

Regulatory effect of castration on endothelins, their receptors and endothelin-converting enzyme in rat seminal vesicle

OBJECTIVE

To investigate the effects of castration on the expression of endothelins (ETs), ET receptors and ET converting enzyme-1 (ECE-1) in the rat seminal vesicle (RSV).

MATERIALS AND METHODS

Sprague-Dawley rats (3 months old) were surgically castrated or sham-operated, and then killed 7 days after surgery. Biochemical and pharmacological properties and the location of ET receptors in the RSV were determined by a series of binding experiments with [125I]ET-1, using membrane particulates and slide-mounted frozen sections of RSV. Expression levels of ETA and ETB receptor subtypes, ET-1, ET-3 and ECE-1 mRNAs were assessed by relative multiplex reverse-transcription polymerase chain reaction (RT-PCR).

RESULTS

The density of total ET receptors increased significantly in the seminal vesicle of the castrated rat. The predominance of the ETA receptor subtype in the RSV did not change with castration. Autoradiographic studies showed the presence of ET receptors on the smooth muscle and epithelium of the RSV. In addition, RT-PCR showed an up-regulation in the expression of ETA and ETB receptor subtypes, ET-1 and ECE-1 mRNAs in the seminal vesicle of the castrated rat. However, castration caused no significant change in the expression levels of ET-3 mRNA.

CONCLUSION

These findings suggest a regulatory role for testosterone in the expression of the ET receptor system in the RSV.

Changes in ultrastructural characteristics of endolymphatic sac ribosome-rich cells of the rat during development

It has recently been demonstrated that endolymphatic sac (ES) ribosome-rich (dark) cells respond to induced endolymph changes and are thus likely to be involved in endolymph homeostasis. Therefore, we studied the ultrastructural characteristics of rat ES ribosome-rich cells during development in order to determine the cellular distribution of organelles involved in protein metabolism, secretion and absorption, indicative for their contribution to endolymph homeostasis. During embryonal stages ribosome-rich cells contain a limited number and variety of organelles and are predominantly involved in the production of components for cell growth and differentiation. In the young adult stage (P60) three different states of ribosome-rich cells may be distinguished. State A resembles a cell with only limited metabolic activities whereas state B is characterized by numerous different intracellular organelles and is considered to be involved in production and secretion as well as absorption and degradation of complex proteins. A third cellular state, state C, is filled with phagolysosomes and contains very few other organelles. This is considered to be a final (pre)apoptotic state. Autoradiography data suggest that ES ribosome-rich cells are capable of synthesis and secretion of tyrosine-containing proteins and may thus be involved in regulation of the osmolarity of endolymph based on the capacity to bind cations as well as water molecules. In addition, ES ribosome-rich cells appear to synthesize and secrete fucosylated glycoproteins into the endolymph. In conclusion, the present data suggest that ES ribosome-rich cells are actively involved in endolymph homeostasis through secretion and absorption of complex proteins and it is hypothesized that they are able to adapt their function or activities in response to changes in endolymph composition.

Ultrastructural Changes in Subepithelial Capillaries and Their Surrounding Stroma in Rat Prostateand Seminal Vesicle after Castration

The purpose of this study was to clarify the androgen-ablation-induced morphological changes in the capillaries and stroma near the epithelial cells in prostate and seminal vesicles (SV) using transmission electron microscopy (TEM). In ventral prostate (VP) and SV of immature male rats, the luminal areas of subepithelial capillaries and the width of the stromal layers between endothelia and epithelia were measured quantitatively after castration using TEM and a computed image analyzer. The luminal areas of the capillaries were significantly reduced in VP and SV in the short-term after castration. In the stromal layer, the width of the collagen layer surrounding the capillary significantly increased in VP and SV in the long-term after castration. These data suggest that the reduction of the capillaries and the thickening of collagen surrounding them are related to the involution of glandular epithelial cells in VP and SV after castration.

Decay accelerating factor in guinea-pig reproductive organs

Decay accelerating factor (DAF, CD55) expressed in human reproductive organs and gametes is thought to play a pivotal role in protection against autologous complement activation in the genital tract. To further investigate the role of DAF in reproduction, we analysed DAF distribution in reproductive organs using guinea-pigs that express multiple DAF isoforms. In males, significant staining was observed in testis on the elongated spermatids and spermatozoa. Levels of DAF mRNA with a shorter 3' untranslated region were significantly enhanced in testis from 9 weeks of age, indicating the presence of DAF mRNA and protein synthesis of spermatozoa DAF in late haploid germ cells. Epididymal spermatozoa appeared to express DAF on the inner acrosomal membrane as well as over their entire surface. Significant DAF expression was also observed on the epithelium of seminal vesicles from 4 weeks of age, with no increase thereafter in the mRNA. C3 mRNA was not detected in this tissue. In females, DAF was detected on the plasma membranes of oocytes through follicle development and on the apical region of uterine epithelium, although the levels of DAF mRNA in these tissues were low. In addition, DAF was selectively expressed on the apical region of ciliated oviductal epithelial cells. The apical region of the ciliated cells comprising the efferent ductule epithelium was also stained significantly, even at 12 days of age, while other epididymal epithelial cells were hardly stained at any age, suggesting that DAF is constitutively expressed on cilia.

Secretion of mucous granules and other membrane-bound structures: a look beyond exocytosis

The substances that animals secrete at epithelial surfaces include not only small molecules and ions delivered by exocytosis, but also a wide variety of materials in membrane-bound form. The latter include mucous granules of pulmonate molluscs, milk fat globules, and products of apocrine and holocrine secretion. Contents include hydrophobic entities (e.g., lipids, hydrocarbons), protective substances (e.g., mucus), and potentially injurious substances (e.g., digestive enzymes, toxins). In some cases vesicles or granules perform significant functions through enzymatic or other properties of the membrane itself (e.g., mammalian prostasome). Much work is still needed to elucidate the ways in which cells release membrane-bound products and how these products are deployed. The current concentration of research effort on exocytosis as a secretory modus should not divert attention from the remarkable versatility of epithelial cells that are capable of utilizing a variety of ways besides exocytosis to transfer materials and information to the external environment.

Innervation of accessory sex glands in the adult male golden hamster and quantitative changes of nerve densities with age

Enzyme histochemistry and immunohistochemistry were used to determine the types of nerves supplying the ampullary gland, coagulating gland, dorsolateral prostate, ventral prostate and seminal vesicle of the male golden hamster. Quantitative change of dopamine beta-hydroxylase (DbetaH), and neuropeptide Y (NPY) immunoreactive and acetylcholinesterase-stained (AChE-stained) nerves with age was also determined. Using an antibody against protein gene product 9.5, nerves were seen to distribute in subepithelial connective tissues, smooth muscles and adventitial connective tissues. Presumptive catecholaminergic nerves immunoreactive for DbetaH and tyrosine hydroxylase were found mainly in periacinar smooth muscles, while AChE-stained nerves predominantly ramified subepithelial connective tissues. In addition, nerves immunoreactive to NPY, calcitonin gene-related peptide, leu-enkephalin, galanin, substance P, and vasoactive intestinal peptide were also detected. Quantitative estimation at 10, 52 and 78 weeks of age showed that densities of DbetaH and NPY nerves were halved by 52 weeks of age. This level was maintained in older animals. The density of AChE-stained nerves in all glands did not change with age. The ampullary gland appeared to have more AChE-stained nerves. These results were discussed from a comparative viewpoint and with regard to possible implications of aging of peripheral nerves on functioning of the male accessory sex glands.

Effect of castration on the VIPergic innervation and 125I-labelled vasoactive intestinal peptide (VIP) binding sites in the hamster seminal vesicle. A quantitative immunohistochemical and receptor autoradiographic study

In the present work we have investigated the effects of medium- (15 days) and long-term (2 months) castration on vasoactive intestinal peptide (VIP)-immunoreactive nerve fibres and 125I-labelled VIP binding sites in the adult hamster seminal vesicle. The density of VIP- and synaptophysin (general neuronal marker)-containing nerve fibres was determined in immunofluorescently stained cryostat sections using a computerised image analysis system. The morphological analysis of 125I-VIP binding sites in seminal vesicle cryostat sections was performed by quantitative receptor autoradiography. Our results show that the densities of the overall (synaptophysin immunoreactive) and VIPergic innervation increase in both medium and long-term castrated animals. In absolute terms, the quantity of VIP- and synaptophysin- containing nerves is not altered in medium-term castrates, but decreases for synaptophysin in long-term castrates. Medium-term castration does not affect the density of 125I-VIP binding sites in the gland muscular coat, but a significant decrease is observed after long-term castration. In conclusion, our results indicate that whereas VIP nerves are apparently unaffected by castration, 125I-VIP binding sites in the muscular coat of hamster seminal vesicle are sensitive to androgen levels.