[Show abstract][Hide abstract] ABSTRACT: Epididymosomes (apocrine secreted epididymal vesicles) are assumed to play a crucial role in sperm maturation. Our aim has been to analyze the fusogenic properties of bovine epididymosomes and their involvement in the transfer of membrane components (lipids, proteins, plasma membrane Ca(2+)-ATPase 4 [PMCA4]) into bovine sperm. The fusogenic properties of epididymosomes with spermatozoa were investigated in vitro by using octadecyl rhodamine-B (R18)-labeled epididymosomes. Spermatozoa isolated from the epididymal caput showed a higher fusion rate than those taken from the cauda. The fusion rate was dependent on pH and time. Furthermore, the lipid and protein content in spermatozoa changed during epididymal transit and after in vitro fusion with epididymosomes. Following the in vitro fusion of caput spermatozoa with epididymosomes, the cholesterol/total phospholipid ratio of the sperm plasma membrane decreased. The effect was comparable with the cholesterol/total phospholipid ratio of native cauda spermatozoa. Co-incubation experiments of spermatozoa with biotinylated epididymosomes additionally revealed that proteins were transferred from epididymosomes to sperm. To examine the potential transfer of epididymis-derived PMCA4 to spermatozoa, immunofluorescence analysis and Ca(2+)-ATPase activity assays were performed. In caput spermatozoa, the PMCA4 fluorescence signal was slightly raised and Ca(2+)-ATPase activity increased after in vitro fusion. Thus, our experiments indicate significant changes in the lipid and protein composition of epididymal sperm following interaction with epididymosomes. Moreover, our results substantiate the presumption that PMCA4 is transferred to spermatozoa via epididymosomes.
Cell and Tissue Research 05/2013; · 3.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: It is assumed that epididymosomes (apocrine secreted epididymal vesicles)
play a crucial role in the sperm maturation process. The aim of the present
study was to analyze the fusogenic properties of bovine epididymosomes and
as to how they are involved in the transfer of membrane components (lipids,
proteins, plasma membrane Ca2+-ATPase 4 [PMCA4]) into bovine sperm. The
fusogenic properties of epididymosomes with spermatozoa were analyzed in
vitro using octadecyl rhodamine-B (R18)-labeled epididymosomes.
Spermatozoa isolated from the epididymal caput showed a higher fusion rate
than those taken from the cauda. The fusion rate was dependent on pH and
time. Furthermore, the experiments indicated that the lipid and protein contents
in spermatozoa change during epididymal transit and after in vitro fusion with
epididymosomes. Following the in vitro fusion of caput spermatozoa with
epididymosomes it was proven that the chol/pl ratio of the sperm plasma
membrane decreased. The effect was comparable to the chol/pl ratio of native
cauda spermatozoa. Furthermore, co-incubation experiments of spermatozoa
with biotinylated epididymosomes revealed that proteins were transferred from
epididymosomes to sperm. To examine the potential transfer of epididymisderived
PMCA4 to spermatozoa immunofluorescence analysis and Ca2+-
ATPase activity assays were performed. In caput spermatozoa the PMCA4-
fluorescence signal was slightly raised and the Ca2+- ATPase activity increased
after in vitro fusion. Taken together, our experiments indicate significant
changes in the lipid and protein composition of epididymal sperm following the
interaction with epididymosomes. In addition, the results substantiate the
presumption that PMCA4 is transferred to spermatozoa via epididymosomes.
Cell and Tissue Research 01/2013; · 3.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The expression of the plasma membrane Ca(2+) ATPase (PMCA) was analyzed in a series of 84 formalin-fixed and paraffin embedded colon samples including normal mucosa (n = 32), adenoma (n = 19), adenocarcinoma (n = 27), and lymph node metastasis (n = 6) using (i) immunohistochemistry, (ii) mRNA in situ hybridization, and (iii) quantitative reverse-transcriptase PCR. A marked reduction of PMCA4 protein was observed in high-grade adenoma, colon cancer as well as lymph node metastasis, pointing to its potential role in the progression of cancer. However, PMCA4 RNA transcripts were unchanged or even increased in colon carcinomas, suggesting posttranscriptional regulation of PMCA4 during carcinogenesis.
Cancer Investigation 04/2012; 30(4):251-7. · 2.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Neuroendocrine (NE) cells are frequently present in the human prostate and urethra, whereas they are lacking in the other urogenital organs. This study was undertaken as there are only few detailed studies available on the distribution, form and function of NE cells and the structure of excretory ducts of the accessory sex organs in the male rat.
Systematic gross anatomical dissections were combined with immunohistochemical and electron microscopic studies of the excretory ducts of the urogenital glands in male rats, with particular focus on the distribution and ultrastructure of the NE cells.
The topography and structure of the excretory ducts of the different glands were characterized in detail and analyzed for the distribution of NE cells. These are present (in falling frequencies) in the ducts of seminal vesicles and ventral and lateral prostate and are rare in ducts of coagulating gland, dorsal prostate, urethral epithelium, and excretory ducts of the (bulbo) urethral glands. They are absent in the respective glands proper, the deferent duct and ejaculatory ampulla. Approximately 40% of the NE cells of the ventral prostate ducts are of the "open" type, whereas these are less frequent (14%) in the seminal vesicle ducts, where the "closed" type prevails.
NE cells are present in unequal quantities in the excretory ducts of the accessory sex glands, but they are absent in the glands proper and the deferent ducts. This distribution pattern points to a strictly localized function and differentiation potency of NE precursor cells.
The Prostate 06/2011; 72(3):326-37. · 3.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Ca(2+) and Ca(2+)-dependent signals are essential for sperm maturation and fertilization. In mouse sperm the plasma membrane Ca(2+)-ATPase (PMCA) isoform 4 plays a crucial role in Ca(2+) transport. The two major splice variants of PMCA4 are PMCA4a and PMCA4b. PMCA4a differs from PMCA4b in the mechanism of calmodulin binding and activation. PMCA4a shows a much higher basal activity and is more effective than PMCA4b in returning Ca(2+) to resting levels. Knock-out mice carrying a PMCA4-null mutation are infertile because their sperm cannot achieve a hyperactivated state of motility. As sperm reach functional maturity during their transit through the epididymis, the expression of PMCA4a and 4b was assessed in bull testis and epididymis. Quantitative PCR revealed that PMCA4b is the major splice variant in testis, caput, and corpus epididymidis. In contrast, PMCA4a is the major splice variant in cauda epididymidis, whereas sperm are transcriptionally silent. Immunohistochemical staining using a new antibody against bovine PMCA4a located the PMCA4a to the apical membrane of the epithelium of cauda epididymidis, whereas testis, caput, and corpus epididymidis were negative. Western blotting of testis, epididymis, and sperm isolated from caput and cauda epididymidis showed a much higher level of PMCA4a in cauda epididymidis and sperm from cauda epididymidis compared with testis membranes and sperm from caput epididymidis. These findings suggest that PMCA4a is transferred to bovine sperm membranes in cauda epididymidis. This isoform switch may facilitate a higher calcium turnover in sperm necessary to traverse the female genital tract.
Journal of Biological Chemistry 12/2010; 286(10):7938-46. · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The plasma membrane Ca(2+) -ATPase (PMCA) is the main restorer of Ca(2+) balance in sperm. Particularly, PMCA isoform 4 has an essential function in sperm fertility by its participation in gaining sperm hypermotility. PMCA activity is influenced by its lipid environment. Sperm membranes exhibit lipid raft microdomains or detergent-resistant membrane domains, enriched in sphingolipids and cholesterol, forming functional specialized areas. Lipid and protein composition of lipid rafts alters during the capacitation process, which is characterized by a cholesterol efflux. In this study, the localization of PMCA4 in lipid membrane fractions of the sperm plasma membrane was investigated. We identified PMCA4 in both the detergent-resistant membrane (DRM) and in the detergent-soluble (DS) fraction of caput and cauda sperm, respectively. Capacitation did not influence PMCA4 localization. In immunocytochemical studies PMCA4 was co-localized with the lipid raft/DRM marker caveolin in the mid piece of caput and cauda sperm. Functional studies with seminal vesicle major protein PDC-109 showed that the Ca(2+) -ATPase activity in DS fractions of cauda sperm and capacitated cauda sperm was stronger enhanced than in the DRMs. In both fractions the effect was statistically significant. In contrast, in lipid overlay experiments PDC-109 interacted stronger with the lipids extracted from DRMs than with lipids extracted from DS. Our results indicate a possible functional compartmentalization of PMCA in bull sperm membranes and point to a presumptive, yet unknown interaction partner of Ca(2+) -ATPase and PDC-109, mediating the PDC-109 action from DRMs to the DS fraction of sperm plasma membrane.
International Journal of Andrology 12/2010; 33(6):775-83. · 3.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Growth properties of the prostate are regulated by a variety of hormones and growth factors. Benign prostatic hyperplasia (BPH) is characterized by abnormal epithelial and stromal proliferation. Varying androgen hormone levels in elderly men are correlated with abnormal proliferations of the prostate. Proteinase-activated receptor-2 (PAR2), a subtype of G-protein-coupled receptors, is known to induce multiple biological processes. It could also play a key role in the proliferation and metastasis of prostate cancer, but its effect on BPH pathogenesis is to a great extent unknown.
Localization of PAR2 was determined both in pathologically altered and in normal prostate tissues by using immunohistochemical techniques. PAR2 activity was assessed by measuring changes in intracellular calcium [Ca(2+)](i) following stimulation of cultured stromal cells with a PAR2 agonist (trypsin) and a synthetic PAR2-activating peptide (AP). DHT-dependence of PAR2 expression in prostate cancer and prostatic stromal cell lines was examined with semi-quantitative and quantitative PCR. Cultured stromal cells (hPCPs) were stimulated with PAR2 AP and cell proliferation was determined through [(3)H]-thymidine incorporation.
In comparison to normal prostate, PAR2 expression was increased in BPH stroma. DHT induced a higher expression of PAR2 when sub-physiological DHT-levels were used. Higher levels of DHT produced reduced PAR2 expression. A mitogenic effect was induced by applying PAR2 AP to hPCPs-cells.
In conclusion, we found that PAR2 expression is hormone-dependent in prostatic stromal cells with a negative correlation and we consider it to be an important factor in mitogenesis in BPH.
The Prostate 09/2010; 70(12):1350-8. · 3.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Summary The secretions of rat seminal vesicles from the so-called copulatory plug when getting in contact with the secretions of the coagulating gland. Depending on the sexual activity of the respective animal and the extraction conditions, the protein pattern of the seminal vesicle secretion varies to some extent. We have studied the biochemical properties of the proteins SVS I, SVS II, sulfhydryl oxidase and SVS III-VIII. The most interesting protein is SVS II which is the main substrate of coagulating gland transglutaminase and serves as the most important monomer during semen coagulation. It is highly soluble in acidic solutions. The monomeric polypeptide has a molecular mass of 49 kDa, is glycosylated with fucose, glucose, mannose and N-acetylated sugars and has a highly basic pI of 10.5. Particularly interesting are its functional and structural relationships with actin. It is the first described protein with actin modulating properties that is secreted in an androgen-dependent manner.Zusammenfassung Das Sekret der Rattenblschendrüse bildet den sogenannten Kopulationspfropf, wenn es mit dem Sekret der Koagulationsdrüse in Kontakt kommt. Je nach sexueller Aktivitt des entsprechenden Tiers und den Extraktionsbedingungen variiert das Proteinmuster des Blschendrüsensekrets in gewissen Bereichen. Wir haben die biochemischen Eigenschaften der Proteine SVS I, II, Sulfhydryloxidase und SVS III-VIII untersucht. Das interessanteste Protein ist SVS II, welches das wesentliche Substrat der Transglutaminase der Koagulationsdrüse bildet und das den bedeutendsten Monomeranteil bei der Samenkoagulation darstellt. In saurem Milieu ist es sehr gut löslich. Das monomere Polypeptid hat ein Molekulargewicht von 49 kDa, ist mit Fukose, Glukose, Mannose und N-acetylierten Zuckern glykosyliert und hat einen pI von 10, 5. Von besonderem Interesse sind seine funktionellen und strukturellen Beziehungen zu Aktin. Es ist das erste beschriebene Protein mit Aktin-modulierenden Eigenschaften, das Androgenabhngig sezerniert wird.
[Show abstract][Hide abstract] ABSTRACT: ZusammenfassungFeinstruktur der Affen-Sertoli-Zellen nach CyproteronbehandlungEine vierwöchige Behandlung mit 200 mg Cyproteron pro Tag i.m. erzeugt feinstrukturelle Veränderungen in den Sertolizellen von Rhesusaffen. Die Zahl der tight junctions als der morphologischen Basis der Bluthodenschranke wird zwischen den Sertolizellen reduziert. Außerdem finden sich weniger Mitochondrien, Mikrofüamente und Reduktionen des Golgiapparates bzw. des endoplasmatischen Retikulums. Daneben beobachtet man eine Verdickung der Basalmembran als Ausdruck einer Aktivierung der hier gelegenen Myofibroblasten. Die Mitoseaktivität der A 1-Spermatogonien geht zurück. Dadurch treten immer weniger Spermatogonien in den Spermatogenesecyclus ein. Nach Absetzen der Behandlung beobachtet man ein Aussprossen des rauhen und glatten endoplasmatischen Retikulums und das Auftreten von Mitochondrien vom Tublustyp. Daneben sieht man häufig in den Sertolizellen Cholesterin-kristall-ähnliche Einschlüsse. Gleichzeitig mit dem schlagartigen, aber asynchronen Auftreten von Mitosen bei den A 1-Spermatogonien scheinen die Sertolizellen ihre voile Funktion wieder aufzunehmen. Cyproteron greift vermutlich direkt in den Funktionscyclus der Sertolizellen ein. Möglicherweise wird dadurch die Spermatogenese zusätzlich beeinträchtigt.ResumenEstructura fina de las células de Sertoli del mono (macaca mulatta) después del tratamiento con ciproteronaEl tratamiento con 200 mg. de ciproterona/día i.m. produjo alteraciones de la estructura subcelular en las células de Sertoli, del macaca mulatta. Se redujo el número de los apretados puentes de unión entre las células de Sertoli, que son la base morfológica de la barrera sangre-testículo. Hay también reducción de las mitocondrias microfilamentos y aparatos Golgi, asl como también del retículo endoplásmico.Además, como resultado de la activación de los miofibroblastos localizados aquí, hay un engrosamiento de las membranas basales. Se reduce la actividad mitótica de las espermatogonias A1, por medio del tratamiento, hasta Ilegar a la supresión del flujo continuado de espermatogonias entre los elementos germinales más diferenciados. Después de interrumpir el tratamiento, se encontró un desarrollo renovado del retículo endoplásmico blando y rugoso, y de las mitocondrias de tipo tubular y un aumento en el número de microcuerpos e inclusiones parecidas a los cristales de colesterol en las células de Sertoli, así como un aumento del crecimiento celular hacia la luz de los tubos. Las células de Sertoli parecían haber recuperado su plena funcionalidad. Al mismo tiempo, la actividad divisional de las espermatogonias A1 en los tubos, se produce de forma súbita aunque asíncronica. La ciproterona parece actuar directamente sobre la célula de Sertoli inhibiendo su función. Ello hace presumible que la ciproterona reduce la espermatogénesis.
[Show abstract][Hide abstract] ABSTRACT: The ultrastructure of the testis was studied in chronically uremic rats with and without administration of hCG. Concomitantly, sham operated pair fed control rats were examined. In uremic rats the seminiferous tubules contained a certain number of necrotic spermatocytes and spermatids with defective acrosome formation. The Sertoli cells showed evidence of reduced function: they had only scarce endoplasmic reticulum and lipid droplets. Leydig cells were rather heterogeneous with respect to ultrastructure. Some cells had poorly developed endoplasmic reticulum, a small Golgi apparatus and no lipid droplets, while others appeared normal. Administration of hCG had marked effects on Leydig cells: such cells acquired numerous mitochondria and rough endoplasmic reticulum, while smooth endoplasmic reticulum, lipid droplets, lysosomes and Golgi apparatus were inconspicuous. In contrast, administration of hCH failed to reverse premature germ cell loss.
[Show abstract][Hide abstract] ABSTRACT: The morphology and functional activity of rat seminal vesicles from normal animals were compared to those administered 3 weeks the synthetic ergot alkaloid lisuride hydrogenmaleate (LHM) with or without simultaneous prolactin substitution and to those from rats castrated 3 days previously. The secretory cells in seminal vesicle epithelium of LHM-treated animals showed regressive changes, irrespective to simultaneous prolactin treatment. Castration resulted in a sharp drop of serum testosterone and consequently in a significant decrease in protein biosynthesis of tissue slices. LHM treatment depressed serum prolactin levels, but testosterone levels and protein biosynthesis were in the normal ranges. In LHM-treated, prolactin-substituted animals both the prolactin and testosterone levels were low, but amino acid incorporation of tissue slices was unaltered. The results indicate that the expected changes of prolactin depression on seminal vesicle functions are obscured by the toxic effects of LHM. LHM treatment is therefore inappropriate for the study of prolactin depletion on the functions of the rat seminal vesicle.
[Show abstract][Hide abstract] ABSTRACT: A glycoprotein, designated SVS II, is secreted in an androgen-dependent manner from lateral prostate and seminal vesicles of the rat. The pI of the protein is 10.5 and it has a molecular mass of 49 kDa. F-actin isolated from skeletal and heart muscle is precipitated at a ratio of 2:1 by SVS II. Using a polyclonal rabbit antibody against SVS II, we found an immunoreaction at the head region of rat spermatozoa removed from the vas deferens. In addition, immunoreactive material was observed in the principal piece of the sperm tail in those spermatozoa. We have studied the distribution of SVS II-immunoreactive material in spermatozoa isolated from seminiferous tubules, proximal (efferent ductules), and distal (caudal epididymal duct) epididymis, both in sexually active and inactive rats and found a differential reactivity pattern. Immunoreactivity observed in the principal piece of the sperm tail develops only immediately before spermiation and does not change during the epididymal transit of the spermatozoa. Immunolabelling seen in the head portion is first observed in spermatozoa from proximal epididymis. Simultaneous with its appearance, rhodamine-labelled phalloidin, indicating the presence of F-actin, no longer binds to that region. While the immunoreaction of the sperm head is attributed to extrinsic SVS II, added to the sperm head in proximal epididymis, the immunoreactivity of the sperm tail seems to result from a cross reactive intrinsic sperm tail protein that achieves its final structure briefly prior to the onset of spermiation.(ABSTRACT TRUNCATED AT 250 WORDS)
[Show abstract][Hide abstract] ABSTRACT: The influence of long (light:darkness LD 16:8) and short (LD 8:16) photoperiods on the morphology of the ventral prostate gland and the seminal vesicles of the Djungarian hamster was investigated. At LD 8:16, the wet weight of the glands was reduced to 15-20% of the values found in animals living in LD 16:8 conditions, the protein content was reduced to 3-4%. The glands showed distinct signs of atrophy and inactivity under short-day conditions. The androgen receptor levels were determined in both accessory sex glands. The receptor levels were comparable in both glands; the absolute values related to the whole glands remained about constant in animals living in long and short photoperiods despite a reduction of the androgen levels in short photoperiods.
[Show abstract][Hide abstract] ABSTRACT: Testicular biopsies from two brothers with pathologic spermatograms revealed a spermatogenetic arrest at early spermatid maturation. No sign of acrosome or sperm tail formation was found in spermatids. Using a polyclonal antibody against vimentin, Sertoli cells appeared in the normal shape and distribution pattern. At the ultrastructural level no significant pathologic alterations of Sertoli cells were visible. A monoclonal antibody against tubulin gave a diffuse perinuclear reaction in spermatogonia, spermatocytes and spermatids. Some tubulin-immunoreactive material was also present in the apical portions of the Sertoli cells. Ultrastructural studies of spermatids revealed a complete absence of the centrioles and axonemal structures in early spermatids. Acrosome formation was inhibited at the early Golgi stage. The numerous spermatids present within germinal epithelium contained an abundance of elongate mitochondria and membrane profiles surrounding the nucleus. The ultrastructural findings indicate a maturation stop of spermatids at a very early stage with complete inhibition of acrosome and sperm tail formation. The underlying mechanism could be a lack of specific structural proteins.
[Show abstract][Hide abstract] ABSTRACT: Calcium fluxes across the plasma membrane of spermatozoa are part of the signal transduction pathway during sperm capacitation. To identify the topography, the time sequence and frequency of calcium fluxes in motile human spermatozoa, individual spermatozoa have to be locally immobilized in a measurement chamber to allow the quantification of ionized calcium by use of a microspectro-photometric method (FURA-2AM). In this study, we compared different immobilization methods using agarose-, gelatin-, laminin- and poly-L-lysine-coated glass slides. Optimal results were obtained with poly-L-lysine coating, which permitted the adhesion of motile spermatozoa that could be analysed microspectro-photometrically. The loss of adherent spermatozoa during the washing procedures was below 10%. However, a major disadvantage of poly-L-lysine coating is that this polymer itself induces a low calcium flux in spermatozoa. Comparing all tested variations, laminin offered the best adhesion result without any detectable effects on calcium fluxes. Our method allowed the rapid change of incubation fluid and calcium concentrations around individual motile spermatozoa and the reproducible quantification of calcium fluxes in single motile spermatozoa.
[Show abstract][Hide abstract] ABSTRACT: Acrosin was prepared from boar and bull spermatozoa and its lytic effect in vitro on the zona pellucida of mouse, golden hamster, rabbit, pig and cow was investigated. Depending upon the species studied, ovarian oocytes, ovulated oocytes and preimplantation embryos were obtained for the experiments. While in golden hamster and rabbit the zona pellucida was removed by both acrosins, this effect was absent for bull acrosin in cow and mouse eggs and for boar acrosin in pig and mouse eggs. In those species in which the zona pellucida was not removed by the acrosins after an incubation period of 2 hours even a prolongation up to 24 hours with higher amounts of acrosin, the addition of acrosomal extracts to the incubation buffer (Tyrode solution pH 7.2) or an increase of the pH value up to 8.6 of the acrosin solution had no effect upon the zona pellucida. Our results indicate that at least in vitro, acrosin does not possess the capacity to lyse the zona pellucida in a species specific fashion. Since the lytic effect of boar and bull acrosin on the zona pellucida of ovarian oocytes and preimplantation embryos is not different from that on ovulated oocytes it can be assumed that neither the maturation of the zona pellucida during oogenesis nor its modification after fertilization, change the susceptibility of the zona pellucida to acrosin digestion.
[Show abstract][Hide abstract] ABSTRACT: The seminal vesicles originate in embryos of about 58 mm crown-rump-length from the Wolffian duct under the influence of testosterone. Along with the ampulla of the vas deferens and the ejaculatory duct, they form a functional unit that develops slowly until the onset of puberty. Developmental malformations occur as uni- or bilateral agenesis, aplasia, cysts, or ureterovesicular fistules. After puberty, the glands form sac-like structures which have a capacity of about 3.4-4.5 ccm and contribute about 70% of the seminal fluid. In addition to secretion, they are capable of reabsorption of fluids or dissolved substances, and of spermatophagy (ingestion and degradation of damaged spermatozoa by epithelial cells). Secretory activity of the glands is a measure of testosterone supplementation to the epithelium. Nervous regulation of secretion is realized by cholinergic post-ganglionic, sympathetic (and perhaps parasympathetic) fibres, derived from pelvic plexus. Contraction of the muscular wall occurs under the influence of excitatory adrenergic and modulatory NPY-encephalin-peptidergic nerve fibres. The secretory products of the seminal vesicles encompass (1) ions (K+: 1.1 mM ml-1) (2) low molecular weight substances (fructose: above 1.2 mg ml-1; prostaglandins above 250 microliters ml-1, (3) peptides (endorphin: 330 pg ml-1), and (4) proteins. In addition to plasma protein related forms such as transferrin, lactoferrin, and fibronectin, specific proteins such as semenogelin (52 kDa) are synthesized, the scaffold protein of semen coagulate forming the substrate for PSA (prostate specific antigen), sperm motility inhibitor (ca. 18 kDa), and others (placental protein 5, protein kinase inhibitor, carboanhydrase, 5'-nucleotidase), some of which are immunosuppressive. Therefore, functions of the seminal vesicles concern (a) formation of seminal coagulum, (b) modification of sperm functions (motility, capacitation), and (c) immunosuppression. Additional functions within the female genital system, perhaps during pre-implantation period, are likely, but remain to be proven experimentally.