Zona Pellucida sperm-binding protein 3 receptor distribution during Gopc-/- globozoospermic spermatogenesis

Globozoospermia is a type of teratozoospermia characterized by round morphology of the sperm head. Gopc^-/- infertile globozoospermic murine model has failures during spermiogenesis, such as the incorrect biogenesis of the acrosome, disorganized acroplaxome and manchette, round nuclei and spiral flagella. In this study, Western blot, RT-PCR, immunohistochemistry and immunogold were done for the localization of the acrosome protein Zona Pellucida sperm-binding protein 3 receptor (ZP3R), also called sp56, in wild type and Gopc^-/- mice testis. The ZP3R protein was located in the acrosome and pseudo-acrosome vesicles of wild type and Gopc^-/- mice, respectively. Also, it is distributed through the cytoplasm of the haploid spermatids only. The incorrect spermiogenesis of Gopc^-/- mice causes a deregulation in the expression of ZP3R in the globozoospermic spermatids. Our results suggest that although the lack of GOPC causes a failure during the transport of the pre-acrosomal vesicles, the acrosome protein ZP3R is localized in the acrosome and is distributed through the cytoplasm only during spermiogenesis. Furthermore, the failure in spermiogenesis does not impair the synthesis of ZP3R and its localization in the pre-acrosomal vesicles.

Identification of sugar moieties in chief cells of the rat fundic gastric glands

Many studies have been conducted to determine the composition of the glycoconjugates of the mucus-secreting cells of the fundic glands of the stomach. However, the chief cells of these glands have been largely ignored because they secrete mainly zymogens with a lower glycosylation. The aim of this work was to analyze the glycoconjugates of the gastric chief cells by a battery of 17 different lectins, recognizing Fucose, N-acetylgalactosamine, Galactose, N-acetylneuraminic acid, N-acetylglucosamine and Mannose containing oligosaccharides. Histochemical techniques were performed with several lectins and also combined with two pre-treatments; β-elimination, which removes O-linked oligosaccharides, and incubation with Peptide-N-Gycosidase F, which removes N-linked oligosaccharides. In addition, acid hydrolysis was performed before WGA histochemistry, and incubation with glucose oxidase before Con A labeling. Many lectins did not stain the chief cells. In addition, the presence of O-glycans in the apical cell membrane was demonstrated with the lectins AAL, HPA, MPA/MPL, PNA, RCA-I, and WGA. Some of these O-glycans were resistant to short-term β-elimination pre-treatments. Mannose-binding lectins stained the basal cytoplasm of the chief cells. The level of glycosylation of the chief cells was lower than that of the mucous cells. The presence of O-glycans in the apical cell membrane is consistent with the presence of mucins such as MUC1 in the apical membrane of chief cells. Moreover, Mannose-binding lectins revealed N-glycosylation in the basal cytoplasm. The knowledge of gastric chief cell glycoconjugates is relevant because of their potential involvement not only in in physiological but also in pathological processes, such as cancer.

Increase of germ cell nuclear factor expression in globozoospermic Gopc-/- knockout mice

BACKGROUND

Golgi-associated PDZ and coiled-coil motif-containing protein (GOPC) is a Golgi protein that plays a role in vesicular transport and intracellular protein trafficking and degradation. Mice deficient in GOPC protein have globozoospermia and are infertile. The germ cell nuclear factor (GCNF) is a member of the nuclear receptor superfamily which is expressed in male germ cells, from spermatocytes and spermatids, both in the nucleus and the acrosomal region. It is not known if its expression could be altered in Gopc^-/- mice with defective acrosomes.

OBJECTIVES

The aim of the present work was to analyze the distribution of GCNF protein in spermatids of Gopc^-/- knockout mice.

MATERIALS AND METHODS

We have analyzed the expression and distribution during spermatogenesis of GCNF and its deregulation in Gopc^-/- mutant mice by RT-qPCR, Western blot, immunohistochemistry and immunogold.

RESULTS

Germ cell nuclear factor was localized in the nucleus of all the cell types in the seminiferous tubules. Despite being a nuclear protein, it was also located in the acrosome and in the manchette of elongating spermatids. We have found that in the absence of GOPC, the expression of GCNF was increased in the nucleus of spermatocytes, mainly in leptotene, and in the nucleus and the manchette during the spermatid elongation.

DISCUSSION AND CONCLUSION

Gopc^-/- mice have defective acrosome and manchette. The manchette is involved in the transport of proteins through the cytoplasm and the nucleus. Considering that the GCNF protein is normally transported to the acrosome and the nucleus, it can be thought that transport deficiencies in Gopc^-/- mice are responsible for the increased expression of this protein.

OPENCRONIC Study. Knowledge and Experiences of Spanish Patients and Carers about Chronic Disease

Background: Chronic diseases are currently the main cause of morbidity and mortality and represent a major challenge to healthcare systems. The objective of this study is to know Spanish public opinion about chronic disease and how it affects their daily lives. Methods: Through a telephone or online survey of 24 questions, data was gathered on the characteristics of the respondents and their knowledge and experiences of chronic diseases. Results: Of the 2522 survey respondents, 325 had a chronic disease and were carers, 1088 had a chronic disease and were not carers, 140 did not have a chronic disease but were carers, and 969 did not have chronic disease and were not carers. The degree of knowledge on these diseases was good or very good for 69.4%, 56.0%, 62.2%, and 46.7%, respectively, for each group. All the groups agreed that chronic diseases mainly affect mood, quality of life and having to make sacrifices. Conclusions: Knowledge about chronic diseases is relatively good, although it can be improved among the Spanish population, especially among patients who report having a chronic disease and play the role of carers. However, it is important to continue maintaining the level of information and training concerning these diseases.

Different Glycoconjugate Content in Mucus Secreting Cells of the Rat Fundic Gastric Glands

The fundic glands of the stomach contain two types of mucous cells: surface mucous cells (SMCs) located at the surface of the stomach and the pits, and mucous neck cells (MNCs) situated in the neck of the glands. They produce mucins, highly glycosylated proteins. Very little is known about the glycan composition of these mucins and of gastric secretion in general. We used several lectins combined with deglycosylation pretreatments to analyze the glycan composition of SMCs and MNCs. The results showed the presence of terminal sialic acid and subterminal Gal and GalNAc, which is consistent with previous knowledge about glycosylation in mucins. Our results also support previous reports that showed a different expression of mucins in the SMCs, depending on their superficial or deep location in the pit. Some lectins labeled only the perinuclear region of the SMCs, but not the apical region, where the secretory granules are stored. This suggests that the lectins are labeling sugar residues that are accessible to lectins during the first steps of glycan synthesis, which occurs in the endoplasmic reticulum and Golgi apparatus. Our results indicate that SMCs and MNCs produce a mucus secretion with a different glycoconjugate composition. The secretion is more varied in SMCs. As our results coincide with what we know about glycosylation of mucins, we can conclude that most of the glycans detected belong to mucins, and the differences in glycosylation observed in each cell type may be due, mainly, to the different secreted mucins. Anat Rec, 301:2128-2144, 2018. © 2018 Wiley Periodicals, Inc.

Transdifferentiation of mucous neck cells into chief cells in fundic gastric glands shown by GNA lectin histochemistry

The epithelium of the gastric mucosa and its glands in the corpus of rat stomach contains mucous surface cells (MSCs), parietal cells, mucous neck cells (MNCs), zymogenic or chief cells (ZCs), several types of enteroendocrine cells, and intermediate cells with characteristics between MNCs and ZCs also called transitional or prezymogenic cells (pre-ZCs). The aim of our work was to analyze the expression of Mannose (Man) in the rat gastric glands by means of Galanthus nivalis lectin (GNA) histochemistry to identify the differences between MNC, pre-ZCs and ZCs and to establish the relationships between these cells. Most of the cytoplasm of MNCs was negative for GNA histochemistry. Intensity of GNA labeling in the gastric gland showed a graduation from pre-ZCs (weak labeling) to ZCs (moderate labeling). Labeling of ZCs was stronger at the perinuclear and apical cytoplasm. In the last years, strong evidence has been reported supporting that ZCs differentiate from MNCs. Our work also supports the origin of ZCs from MNCs, because the GNA labeling graduation might be due to oligosaccharides which are not expressed in MNCs, start to express in pre-ZCs and are more abundant in ZCs, indicating that differentiation from MNCs to ZCs is a process in which glycans with Man moieties are synthesized.

Morphofunctional basis of the different types of angiogenesis and formation of postnatal angiogenesis-related secondary structures

We review the morpho-functional basis of the different types of angiogenesis and report our observations, including the formation of angiogenesis-related secondary structures. First of all, we consider the following issues: a) conceptual differences between angiogenesis and vasculogenesis, b) incidence of angiogenesis in pre- and postnatal life, c) regions of vascular tree with angiogenic capacity, d) cells (endothelial cells, pericytes, CD34+ adventitial stromal cells of the microvasculature and inflammatory cells) and extracellular matrix components involved in angiogenesis, e) events associated with angiogenesis, f) different types of angiogenesis, including sprouting and intussusceptive angiogenesis, and other angiogenic or vascularization forms arising from endothelial precursor cells (postnatal vasculogenesis), vasculogenesis mimicry, vessel co-option and piecemeal angiogenesis. Subsequently, we consider the specific morpho-functional characteristics of each type of angiogenesis. In sprouting angiogenesis, we grouped the events in three phases: a) activation phase, which includes vasodilation and increased permeability, EC, pericyte and CD34+ adventitial stromal cell activation, and recruitment and activation of inflammatory cells, b) sprouting phase, encompassing EC migration (concept and characteristics of endothelial tip cells, tip cell selection, lateral inhibition, localized filopodia formation, basal lamina degradation and extracellular changes facilitating EC migration), EC proliferation (concept of endothelial stalk cells), pericyte mobilization, proliferation, recruitment and changes in CD34+ adventitial stromal cells and inflammatory cells, tubulogenesis, formation of a new basal lamina, and vascular anastomosis with capillary loop formation, and c) vascular remodelling and stabilization phase (concept of phalanx cells). Subsequently, the concept, incidence, events and mechanisms are considered in the other forms of angiogenesis. Finally, we contribute the formation of postnatal angiogenesis-related secondary structures: a) intravascular structures through piecemeal angiogenesis, including intravascular papillae in vessel tumours and pseudotumours (intravascular papillary endothelial hyperplasia, vascular transformation of the sinus in lymph nodes, papillary intralymphatic angioendothelioma or Dabska tumour, retiform hemangioendothelioma, hemangiosarcoma and lymphangiosarcoma), vascular septa in hemorrhoidal veins and intravascular projections in some tumours; b) arterial intimal thickening; c) intravascular tumours and pseudotumours (e.g. intravenous pyogenic granulomas and intravascular myopericytoma); d) vascular glomeruloid proliferations; and e) pseudopalisading necrosis in glioblastoma multiform.

Intravascular papillary endothelial hyperplasia (IPEH). Evidence supporting a piecemeal mode of angiogenesis from vein endothelium, with vein wall neovascularization and papillary formation

Intravascular papillary endothelial hyperplasia (IPEH) is a reactive process of questioned pathogenesis (primary proliferation of endothelial cells/ECs versus organizing thrombi). The aim of this study is to assess the organization of morphologic patterns, with precise location of neovascularization and papillary distribution in IPEH to clarify the role of the vein wall (mainly vein intimal ECs) in lesion development and papillary formation. We studied 12 cases of IPEH in skin and subcutaneous veins by serial histological sections and immunohistochemical procedures. In four well-structured cases (the remaining cases showed overlapping events), we found four principal histological patterns organized by zone: 1) invaginated vein wall zone with microvascular networks. The intraparietal microvessels presented CD34+ and CD31+ ECs arising from ECs of the vein intima, and αSMA+ pericyte-like cells originating from modified SMCs of the media layer. 2) Papillary zone, generally with myriad papillae, formed by ECs of intraparietal microvessel networks encircling vein wall components (parietal papillae). 3) Organizing thrombotic zone from microvascular networks of invaginated vein wall zone. 4) Unorganized thrombotic zone partially covered by ECs, also originating from vein intimal endothelium and arranged in a monolayer or encircling thrombotic fibrin (thrombotic papillae). In conclusion, the capacity of vein intimal ECs and those originating from them (in newly-formed microvessels in the vein itself and covering the unorganized thrombi) to encircle vein wall components or fibrin, and to form papillae (ECs form the cover and encircled components the core) supports a piecemeal mode of angiogenesis as a pathogenic basis of IPEH. This mechanism encompasses the two histogenetic hypotheses outlined above.

Telocyte Behaviour During Inflammation, Repair and Tumour Stroma Formation

In this chapter, we outline the role of human CD34+ stromal cells/telocytes (CD34+ SC/TCs) as progenitor cells during repair. The in vivo activation phenomena of CD34+ SC/TCs in this process include increased size; separation from the neighbouring structures (mainly of the vascular walls); association with inflammatory cells, predominantly macrophages; development of the organelles of synthesis (rough endoplasmic reticulum and Golgi apparatus); cell proliferation with presence of mitosis and high proliferative index (transit-amplifying cells); and fibroblastic and myofibroblastic differentiation. A procedure to study these tissue-resident cells, comparison of their behaviour in vivo and in vitro and different behaviour depending on location, time, type of injury (including tumour stroma) and greater or lesser proximity to the injury are also considered.

Changes in Testicular Interstitial Connective Tissue of Hamsters (Mesocricetus auratus) During Ageing and After Exposure to Short Photoperiod

The testicular interstitium of Syrian hamster (Mesocricetus auratus) was studied during ageing and in testicular regression after exposure to a short photoperiod, in relation to the interstitial cells and their connective tissue. This tissue was assessed histochemically using Masson's trichrome technique and the expression of Heat Shock Protein 47 (HSP-47) and collagen IV (α5) was assessed in Leydig cells. Finally, an ultrastructural analysis of some cells of the testicular interstitium was made. Leydig cells were positive for HSP-47 and collagen IV (α5). Ageing did not change the parameters studied while the short photoperiod altered the synthetic activity of Leydig cells. The positivity index of these cells for HSP-47 was significantly higher in the regressed testis, but was lower for collagen IV (α5). During ageing no change were observed. Ultrastructural Leydig cells showed a discontinuous basal lamina that did not change during ageing. The basal lamina was not identified in Leydig cells regressed by exposure to a short photoperiod. In conclusion; the intertubular connective tissue suffers little change with age. By contrast, in the testis regressed after exposure to a short photoperiod the studied parameters related to the intertubular connective tissue were altered. These changes are probably related with the low synthetic activity of regressed Leydig cell.

Human resident CD34+ stromal cells/telocytes have progenitor capacity and are a source of αSMA+ cells during repair

We studied the progenitor capacity of human resident CD34+ stromal cells/telocytes (SC/TCs) in the enteric wall affected by inflammatory/repair processes (appendicitis, diverticulitis of large bowel and Crohn's disease of the terminal ileum) at different stages of evolution (inflammatory, proliferative and remodelling). In these conditions, CD34+ SC/TCs are activated, showing changes, which include the following overlapping events: 1) separation from adjacent structures (e.g., from vascular walls) and location in oedematous spaces, 2) morphological modifications (in cell shape and size) with presence of transitional cell forms between quiescent and activated CD34+ SC/TCs, 3) rapid proliferation and 4) loss of CD34 expression and gain of αSMA expression. These events mainly occur in the inflammatory and proliferative stages. During the loss of CD34 expression, the following findings are observed: a) irregular cell labelling intensity for anti-CD34, b) co-localization of CD34 and actin, c) concurrent irregular labelling intensity for αSMA and d) αSMA expression in all stromal cells, with total loss of CD34 expression. While CD34 expression was conserved, a high proliferative capacity (Ki-67 expression) was observed and vice versa. In the segments of the ileum affected by Crohn's disease, the stromal cells around fissures were αSMA+ and, in the transitional zones with normal enteric wall, activated CD34+ SC/TCs were observed. In conclusion, human resident CD34+ SC/TCs in the enteric wall have progenitor capacity and are activated with or without differentiation into αSMA+ stromal cells during inflammatory/repair processes.

The death of sertoli cells and the capacity to phagocytize elongated spermatids during testicular regression due to short photoperiod in Syrian hamster (Mesocricetus auratus)

In the Syrian hamster (Mesocricetus auratus), an animal that displays testicular regression due to short photoperiod, germ cells are removed by apoptosis during this process and the apoptotic remains are phagocytized by Sertoli cells. The aim of this work was to investigate morphologically whether the testicular regression process due to short photoperiod leads to the apoptosis of Sertoli cells, and whether, during testicular regression, the elongated spermatids are eliminated through phagocytosis by Sertoli cells. To this end, we studied testis sections during testicular regression in Syrian hamster subjected to short photoperiod by means of several morphological techniques using conventional light microscopy (hematoxylin and eosin [H&E], semi-thin section vimentin, immunohistochemistry, SBA lectin, and TUNEL staining), fluorescence microscopy, and transmission electron microscopy (TEM). H&E and semi-thin sections identified Sertoli cells with a degenerated morphology. Greater portion of Sertoli cells that were positive for TUNEL staining were observed especially during the mild regression (MR) and strong regression (SR) phases. In addition, TEM identified the characteristic apoptotic changes in the nucleus and cytoplasm of Sertoli cells. Moreover, during testicular regression and using light microscopy, some elongated spermatids were seen in basal position next to the Sertoli cell nucleus. This Sertoli phagocytic activity was higher in MR and SR phases. TEM confirmed this to be the result of the phagocytic activity of Sertoli cells. In conclusion, during testicular regression in Syrian hamster due to short photoperiod, when germ cells are known to be lost through apoptosis, there is morphological evidences that Sertoli cells are also lost through apoptosis, while some elongated spermatids are phagocytized and eliminated by the Sertoli cells.

CD34+ stromal cells/fibroblasts/fibrocytes/telocytes as a tissue reserve and a principal source of mesenchymal cells. Location, morphology, function and role in pathology

We review the morphofunctional characteristics of CD34+ stromal fibroblastic/fibrocytic cells (CD34+ SFCs) and report our observations. We consider the following aspects of CD34+ SFCs: A) The confusing terms applied to this cell type, often combining the prefix CD34 with numerous names, including fibroblasts, fibrocytes, dendrocytes, keratocytes, telocytes and stromal, dendritic, adventitial, supraadventitial, perivascular, paravascular and delimiting cells; B) Changes in their immunophenotype, e.g., loss of CD34 expression and gain of other markers, such as those defining mesenchymal and derivate cells (myofibroblasts, osteoblasts, chondroblasts, adipocytes); C) Morphology (elongated or triangular cell body and thin, moniliform, bipolar or multipolar cytoplasmic processes), immunohistochemistry (co-expression of and changes in molecular expression) and structure (characteristics of nucleus and cytoplasmic organelles, and points of contact and junctions in quiescent and activated stages by light and electron microscopy); D) Location and distribution in the vessels (adventitia or external layer), in the tissues (connective, adipose, blood, muscle and nervous) and in the organs and systems (skin, oral cavity and oropharynx, respiratory, digestive, urinary, male, female, endocrine and lymphoid systems, serosal and synovial membranes, heart, eye and meninges); E) Origin from the mesoderm and cranial neural crest in the embryo, and from stem cells (themselves or other cells) and/or peripheral blood pluripotent stem cells (circulating progenitor cells) in post-natal life; F) Functions, such as synthesis of different molecules, progenitor of mesenchymal cells, immunomodulation, parenchymal regulation (growth, maturation and differentiation of adjacent cells), induction of angiogenesis, scaffolding support of other cells and phagocytic properties. Since CD34+ SFCs are the main reservoir of tissue mesenchymal cells (great mesenchymal potential, probably higher than that proposed for pericytes and other stromal cells), we dedicate a broad section to explain their in vivo behaviour during proliferation and differentiation in different physiologic and pathologic conditions, in addition to their characteristics in the human tissues of origin (adult stem cell niches); G) Involvement in pathological processes, e.g., repair (regeneration and repair through granulation tissue), fibrosis, tumour stroma formation and possible CD34+ SFC-derived tumours (e.g., solitary fibrous tumour, dermatofibrosarcoma protuberans, giant cell fibroblastoma, nuchal-type fibroma, mammary and extramammary myofibroblastoma, spindle and pleomorphic cell lipoma, and elastofibroma) and H) Clinical and therapeutic implications.

Histochemical identification of sialylated glycans in Xenopus laevis testis

Carbohydrate chains of glycoprotein and glycosphingolipids are highly diverse molecules involved in many cell functions, including cell recognition, adhesion and signalling. Sialylated glycans are of special interest because the terminal position of sialic acid (NeuAc) in glycans linked by different ways to subterminal monosaccharides has been shown to be involved in several biological processes, as occurs with gangliosides, which have been reported as being essential in spermatogenesis in mammals. Some glycan-binding proteins, the lectins, which specifically recognize glycan sequences, have been extensively used to characterize tissue and cell carbohydrates by means of cytochemical techniques. The aim of the present work was to determine the presence of NeuAc by means of histochemical techniques in the testis of Xenopus laevis, an animal model widely used in cell and molecular biology research. However, considering that some NeuAc-binding lectins are capable of binding to N-acetylglucosamine (GlcNAc), other GlcNAc-binding lectins were also assayed. The results showed that NeuAc is mainly expressed in the interstitium, and only a weak labelling in the male germ cells was observed. Most NeuAc was located in O-linked oligosaccharides, but some masked NeuAc in N-glycans were identified in primary and secondary spermatogonia and spermatocytes. By contrast, GlcNAc was widely expressed in all germ cell types. Deglycosylative pre-treatments suggest that both N- and O-glycans and/or glycolipids could be responsible for this labelling. In addition, GlcNAc in O-linked oligosaccharides has been identified in spermatogonial cells. The acrosome of spermatids was always negative. Variations of glycan expression have been found in different cell types, suggesting that glycosylation is modified during spermatogenetic development.

Peg-and-socket junctions between smooth muscle cells and endothelial cells in femoral veins are stimulated to angiogenesis by prostaglandin E₂ and glycerols

The administration of prostaglandin (PG) E2, triacetylglycerol and glycerol induce the formation of numerous vascular buds arising from the femoral vein, as previously demonstrated by our group. In the present study, a great number of peg-and-socket junctions (PSJs) between smooth muscle cells (SMCs) (providing the pegs) and ECs (forming the sockets) were demonstrated. At the first stage, days 1 to 3, PSJs connect subendothelial penetrating processes from activated SMCs with activated ECs of the intima. Subsequently, during angiogenesis (days 4 to 6), SMCs, showing transitional aspects with pericytes, also form PSJs with intimal ECs, but also new PSJs between SMCs and sprouting ECs in the media layer were now observed. Immunohistochemically, α-smooth muscle actin (α-SMA) and H-caldesmon are positive in the cytoplasm of the SMCs, showing a higher expression in pegs. Desmin, however, although it is also positive in the cytoplasm of the SMCs, is negative in the pegs. The expression of CD34 in ECs reveals abundant positive folding that appears to correspond to the sockets. The peculiar expression of caldesmon, whose isoforms may contribute to the regulation of cell motility, and to vasculogenesis and angiogenesis, may have a role in the different mechanisms by which PSJs act in the vein wall.

Acrosome biosynthesis in spermatocytes and spermatids revealed by HPA lectin cytochemistry

The origin of the acrosome is controversial, because of both its lysosomal nature and at the moment of its appearance, which seems to be species-specific. Considering the amazing organization shown by the acrosome of some urodele amphibians, HPA-colloidal gold cytochemistry was used to analyze the biogenesis of the acrosome in the urodele Pleurodeles waltl at electron microscopy level. The results showed that HPA-labeling is useful to label the acrosome and its precursor vesicles and, consequently, HPA-histochemistry could be used as a marker of acrosomal content. Labeling of the Golgi apparatus and precursor vesicles was seen in primary spermatocytes and round (stage I) spermatids, thus contributing solid evidence for the beginning of acrosome biogenesis before meiosis. In both primary spermatocytes and round spermatids, an enigmatic vesicle, probably related to the biosynthesis of the neck piece or the tail, was also labeled. Labeling in elongating spermatids (stage II-IV), showed a homogeneous distribution of colloidal gold particles in the acrosomal cap, but the perforatorium was not positive to the lectin. However, in mature (stage V-VI) spermatids, a regional distribution of labeling in the acrosome was seen, with the apical knob showing a stronger labeling than the lateral barb, and the lateral barb showing a stronger labeling than the principal piece of the acrosomal cap. This regional distribution of the labeling suggests that the acrosome develops several domains with different glycoconjugate compositions.

Histochemical demonstration of two subtypes of O-linked oligosaccharides in the rat gastric glands

The gastric glands synthesize glycoproteins whose oligosaccharides are linked to the peptide core mainly by the O-glycosidic bond, specifically removed by beta-elimination procedure. Our aim was to research the possibility of the existence of two subtypes of O-linked oligosaccharides with a different behavior to the removal procedure. The lectins from peanut (PNA) and Maackia amurensis (MAA-I) were histochemically used as markers of the O-linked oligosaccharides. Sections were also pretreated with beta-elimination and/or peptide N-Glycosidase F (PNGase-F) for the specific removal of O- and N-linked oligosaccharides, respectively. The lectin GNA, which mainly labels to N-linked oligosaccharides, was used to test the correct working of PNGase-F. To test the possibility that the beta-elimination treatment could remove the terminal sialic acid residues, the lectin LFA was used. The surface epithelium was negative to PNA, while it became strongly positive when beta-elimination was performed for 1 day. This staining was resistant to PNGase-F, suggesting that PNA was labeling to O-linked oligosaccharides. However, after beta-elimination for 5 days this staining is not observed. A similar pattern appeared with MAA-I. We propose the existence of two subtypes of O-linked oligosaccharides: labile and resistant. The labile O-linked oligosaccharides are removed with beta-elimination for 1 day, unmasking the PNA-positive oligosaccharides. These oligosaccharides are resistant O-linked oligosaccharides because staining is abolished with longer treatment of beta-elimination. The results with MAA-I also support this suggestion. In summary, the labile O-linked oligosaccharides are removed with short treatment, while the resistant O-linked oligosaccharides need a stronger procedure (for 5 days).

Identification of mannose moieties in N- and O-linked oligosaccharides of the primordial germ cells of Xenopus embryos

The presence of mannose (Man) in the glycoconjugates of primordial germ cells (PGCs) of Xenopus embryos was elucidated by lectin histochemistry with Concanavalin A (Con A) and snowdrop (Galanthus nivalis) bulb lectin (GNA), in combination with deglycosylative pretreatments: beta-elimination, which removes O-linked oligosaccharides, and incubation with Peptide N glycosidase F (PNGase F), which removes N-linked glycan chains. In addition, histochemistry with Con A, which binds to Man and glucose (Glc), was also performed after glucose-oxidase incubation, which converts Glc into gluconic acid, and GNA was carried out after acid hydrolysis, which removes terminal sialic acid (NeuAc) moieties. PGCs were analyzed during their migration over the mesentery until the genital ridge, and after colonization of this gonad anlage. The results showed that for both lectins: (1) the PGCs and other surrounding tissue showed a similar binding pattern, and (2) the staining in the PGCs was similar in the developmental stages studied. Labeling with Con A was due to Man, and not to Glc, as shown after incubation with glucose-oxidase, and it was assumed that Man was in N-linked oligosaccharides. However, GNA labeling was mainly due to O-linked oligosaccharides, because the pretreatment of beta-elimination turned cells negative. Moreover, acid hydrolysis pretreatment gave rise to a stronger GNA-staining, suggesting that either Man was also in subterminal position to NeuAc or some Man-containing glycans were unmasked after removal of NeuAc from other oligosaccharide chains.

Glycoconjugates of the urodele amphibian testis shown by lectin cytochemical methods

Lectin histochemistry is a useful method that allows the in situ identification of the terminal sugar moieties of the carbohydrates that form the glycoconjugates. Moreover, when it is combined with chemical or enzymatic deglycosylation pretreatments, lectin histochemistry can be employed to determine if carbohydrates are linked to the protein core by means of an N- or O-glycosidic linkage or, indeed, to partially sequence the sugar chains. One of the most interesting model organs for the study of spermatogenesis is the amphibian urodele testis. However, this organ has not been very widely investigated with lectin histochemical research. In the last few years, we have carried out a research project to identify and locate glycoconjugates in the testis of the urodele Pleurodeles waltl, the Spanish newt, as a first approach to identify possible carbohydrates with key roles in spermatogenesis. Our findings reveal some glycan chains located in a fusome-like structure in early (diploid) germ cells, oligosaccharides with terminal GalNAc in the acrosome, the occurrence of glycan modifications in the acrosomal contents during spermiogenesis, and changes in glycan composition of follicle and interstitial cells during the spermatogenetic cycle. Furthermore, the similar labeling pattern of follicle and duct cells supports the hypothesis for a common origin of both cell types.

GalNAc moieties in O-linked oligosaccharides of the primordial germ cells of Xenopus embryos

Glycoconjugates could play a role in cell adhesion and migration mechanisms, including the locomotive movements of the primordial germ cells (PGCs) during the development of the embryo. In the present work, we have studied by lectin histochemistry the presence of N-acetylgalactosamine (GalNAc) in the glycans of the Xenopus PGCs, as a first approach to identifying their glycoconjugates which could be involved in the migration mechanism. The PGCs were negative for three of the GalNAc-binding lectins employed (from soybean, SBA; from lima bean, LBA; and from snail, HPA). However, when sialic acid (NeuAc) was previously removed by acid hydrolysis, SBA and HPA, but not LBA, labeled the PGCs, except if the staining was combined with the beta-elimination procedure. This suggests the presence of GalNAc alpha(1,3)-linked to galactose (Gal) in O-linked oligosaccharides, in a subterminal position to NeuAc. As the PGCs were always negative for LBA, the absence of fucose alpha(1,2)-linked to subterminal Gal is suggested. With the lectin from horse gram (DBA), the PGCs were stained, although beta-elimination turned the cells negative and acid hydrolysis increased the labeling, suggesting that GalNAc(alpha)(1,3)GalNAc was in O-linked glycans in terminal and subterminal to NeuAc position.

Glycan composition of follicle (Sertoli) cells of the amphibian Pleurodeles waltl. A lectin histochemical study

The glycan composition of the N- and O-linked oligosaccharides of the follicle (Sertoli) cells of the urodele amphibian Pleurodeles waltl testis were identified by lectin histochemistry, performed alone or in combination with enzymatic and chemical deglycosylation methods. The follicle cells were shown to contain: (1) Fuc, Galbeta(1,4)GlcNAc, GalNAc and Neu5Acalpha(2,3)Galbeta(1,4)GlcNAc in both N- and O-linked oligosaccharides; (2) Man in N-linked glycans; and (3) Galbeta(1,3)GalNAc in O-linked sugar chains. The follicle cells at the pre- and postmeiotic stages showed some differences in the UEA-1-positive Fuc characterisation, suggesting differences in the glycan composition. In addition, the sequence Neu5Acalpha(2,6)Gal/GalNAc was shown in the follicle cells only after spermiation, in the sperm-empty lobules of the developing glandular tissue. These results suggest that the follicle cells modify their glycoprotein content, probably for the performance of new roles, as the spermatogenetic cells develop. Thus the follicle cells surrounding male germ cells at different spermatogenetic stages would contain different glycoproteins involved in specific roles during male germ cell proliferation and maturation.

Galactosides and sialylgalactosides in O-linked oligosaccharides of the primordial germ cells in Xenopus embryos

The primordial germ cells (PGCs) are covered by surface glycoconjugates; some of them, like galactose residues recognized by peanut agglutinin (PNA), have been reported to be implicated in the PGC migration process. The aim of this work was the characterization of galactosides and sialylgalactosides in N- and O-linked oligosaccharides of Xenopus PGCs. Galactose(Gal)- and sialic acid(Neu5Ac)-binding lectin cytochemistry, in combination with chemical and enzymatic deglycosylation methods, were used. PGCs were slightly labeled with PNA, RCA-I and BSI-B4, which suggests the presence of the sequences Gal(beta1,4)GlcNAc and Gal(alpha1,3)Gal. Moreover, there was no labeling when beta-elimination pre-treatment was performed, suggesting that galactosides were in O-linked oligosaccharides. The strong staining with DSA was probably due to GlcNAc. Furthermore, sialylgalactosides with the sequence Neu5Ac(alpha2,3)Gal(beta1,4)GlcNAc in O-linked oligosaccharides have been shown by means of MAA, PNA and RCA-I.

Carbohydrate moieties of the interstitial and glandular tissues of the amphibian Pleurodeles waltl testis shown by lectin histochemistry

The amphibian testis is a useful model because of its zonal organisation in lobules, distributed along the cephalocaudal axis, each containing a unique germ cell type. Sperm empty lobules form the so-called glandular tissue at the posterior region of the gonad. Androgen production is limited to the cells of the interstitial tissue surrounding lobules with spermatozoa bundles and to the cells of the glandular tissue. In this work, we have studied the distribution of terminal carbohydrate moieties of N- and O-linked oligosaccharides in the interstitial and glandular tissue of the Pleurodeles waltl testis, by means of 14 lectins combined with chemical and enzymatic deglycosylation pretreatment. Some differences in glycan composition between the interstitial and the glandular tissue have been detected. Thus in both tissues, N-linked oligosaccharides contained mannose, Gal(beta1,4)GlcNAc, and Neu5Ac(alpha2,3)Gal(beta1,4)GlcNAc, while O-linked oligosaccharides contained Con A-positive mannose, Gal(beta1,3)GalNAc, Gal(beta1,4)GlcNAc, Neu5Ac(alpha2,3)Gal(beta1,4)GlcNAc, and WGA-positive GlcNAc. Fucose was also detected in both tissues. However, GlcNAc on N-linked oligosaccharides and GalNAc and Neu5Ac(alpha2,6)Gal/GalNAc on both N- and O-linked oligosaccharides were found only in the interstitial tissue. As glandular tissue cells arise from the innermost cells of interstitial tissue that surround lobules, the differences in the glycan composition of interstitial and glandular tissue shown in this work may be related to the start of androgen synthesis when steroid hormone (SH)-secreting cells develop.

Lectin histochemical identification of the carbohydrate moieties on N- and O-linked oligosaccharides in the duct cells of the testis of an amphibian urodele, the spanish newt (Pleurodeles waltl)

The aim of the present work was to study the carbohydrate moieties present on N- and O-linked oligosaccharides of duct cells of a urodele amphibian testis, by means of lectin histochemistry. It was found that duct cells have a carbohydrate composition that includes alpha(1,3)-, alpha(1,4)- or alpha(1,6)-linked Fuc and Man on N-linked oligosaccharides, Gal and GlcNAc on O-linked oligosaccharides, and DBA-positive GalNAc, alpha(1,2)-linked Fuc and Neu5Ac alpha(2,3)Gal beta(1,4)GlcNAc on both N- and O-linked oligosaccharides. All the duct cells showed the same lectin labelling pattern, the only exception being some sparse duct cells that showed the sequence Neu5Ac alpha(2,6)Gal/GalNAc. The possible roles of duct cells in sperm maturation and the hypothesis for a common origin of duct and follicle (Sertoli) cells in the urodele testis are discussed.

Glycan residues of N- and O-linked oligosaccharides in the premeiotic spermatogenetic cells of the urodele amphibian Pleurodeles waltl characterize by means of lectin histochemistry

The aim of this work was the characterization of the glycoconjugates of the premeiotic spermatogenetic cells of the testis of an urodele amphibian, Pleurodeles waltl, by means of lectins in combination with several chemical and enzymatic procedures, in order to establish the distribution of N- and O-linked oligosaccharides in these cells. In the cytoplasm of the primordial germ cells, primary and secondary spermatogonia and primary spermatocytes, a granular structure can be observed close to the nucleus. These granules contain four types of sugar chains according to their appearance during the differentiation process: 1. some oligosaccharides that are identified in all the four cell types above mentioned, which include N-linked oligosaccharides with Fuc, Gal beta1,4GlcNAc and Neu5Ac alpha2,3Gal beta1,4GlcNAc and O-linked oligosaccharides with Gal beta1,4GlcNAc and Neu5Ac alpha2,3Gal beta1,4GlcNAc; 2. other glycan chains that are not present in the primary spermatocytes (N-linked oligosaccharides with DBA-positive GalNAc, GlcNAc, and a slight amount of Neu5Ac alpha2,6Gal/GalNAc and O-linked oligosaccharides with WGA-positive GlcNAc); 3. the sugar chains that are not in the earliest step of spermatogenesis (formed by both N-linked and O-linked oligosaccharides with Glc); and 4. other that appear at the earliest and latest stages, but not in the intermediate ones, (N-linked oligosaccharides with Man and O-linked oligosaccharides with SBA- and HPA-positive GalNAc and PNA-positive Gal beta1,3GalNAc). This structure could be related with the Drosophila spectrosome and fusome, unusual cytoplasmic organelles implicated in cystic germ cell development. Data from the present work, as compared with those from mammals and other vertebrates, suggest that, although no dramatic changes in the glycosylation pattern are observed, some cell glycoconjugates are modified in a predetermined way during the early steps of the spermatogenetic differentiation process.

Lectin cytochemical characterization of the N- and O-linked oligosaccharides in the human rectum

The oligosaccharides of the mucus glycoproteins of the human rectum are important for the lubricant and protective role suggested for the rectal mucus. Changes in oligosaccharide composition are observed in several colon diseases, and some of these changes could be used as diagnostic and prognostic indicators. Thus, a previous knowledge of the normal mucus glycoproteins is necessary. The aim of the present study is the characterization of the oligosaccharides of the goblet cells and enterocytes of the human rectum. For this, a battery of 15 lectins, in combination with chemical and enzymatic deglycosylation procedures, was used. Our results suggest the presence of N-acetylglucosamine (GlcNAc), Man, Glc, N-acetylneuraminic acid (Neu5Ac)(alpha2-6)- and Neu5Ac(alpha2-3)-linked, N-acetylgalactosamine (GalNAc) and Gal(beta1-3)GalNAc in the oligosaccharides of the goblet cells. Moreover, N-linked oligosaccharides specifically contained Gal(beta1-4)GlcNAc, while AAA-positive Fuc was only detected in O-linked oligosaccharides. Some of these carbohydrates were only visualized after removal of N- or O-linked oligosaccharides, suggesting a high level of approximation between the oligosaccharide chains, that render the carbohydrate inaccessible to the lectins. Differences in the labelling pattern between the goblet cells of the surface epithelium and the upper half of the crypts, and those of the lower half of the crypts suggests a maturation process for the goblet cells, which modifies the oligosaccharide composition of the secreted glycoproteins, as they ascend throughout the crypts. This maturation process includes the incorporation of new carbohydrates (GlcNAc), and the masking (Neu5Ac(alpha2-3)-linked) or unmasking (Glc and GalNAc) of others.

Lectin histochemical localization of N- and O-linked oligosaccharides during the spermiogenesis of the urodele amphibian Pleurodeles waltl

The aim of this work is the characterization of the glycoconjugates of the spermatids during the spermiogenesis of the testis of an urodele amphibian, Pleurodeles waltl, by means of lectins in combination with several chemical and enzymatic procedures, in order to establish the distribution of N- and O-linked oligosaccharides in these cells. The acrosome was the most relevant lectin-labeled structure. The O-linked oligosaccharides contained DBA- and SBA-positive GalNAc, AAA-positive Fuc and PNA-positive Gal beta1,3GalNAc. Sialic acid was scarcely observed, the Neu5Ac alpha2,3Gal beta1,4GlcNAc sequence was found in N-linked oligosaccharides. Additionally, N-linked oligosaccharides containing HPA-positive GalNAc and AAA-positive Fuc were found. Moreover, with some lectins the acrosome showed a variable composition of the oligosaccharides in the different steps of the sperm maturation. Some residues were found only in the early steps in maturating acrosome, while others were in the later steps, showing that acrosomal glycoconjugates are modified during acrosome development in spermiogenesis. The changes observed during acrosome maturation suggest the existence of a predetermined pattern of storage of the acrosome components and a progressive compression of them.

Lectin-gold localization of fucose residues in human gastric mucosa

The oligosaccharides of the mucous gastric glycoproteins are involved in the protection of the gastric mucosa and are altered in different diseases. Therefore, it is important to know their composition in health, to better determine the alterations induced by the disease. Moreover, analysis of the molecular composition of the fundic gland cells has been previously used to obtain new insights into the origin of the different cell types. The aim of the present study was the localization in the subcellular structures of the fucose residues of the oligosaccharides in human fundic glands. For this, lectin cytochemical methods were used at the light and electron microscopic levels. They were combined with enzymatic and chemical treatments to characterize the nature of the oligosaccharide chains containing the fucose residues. The presence of this carbohydrate belonging to N- or O-linked oligosaccharides has been demonstrated in the secretory granules of the surface, gastric pit, mucous neck, and transitional cells of the fundic mucosa, and in the intracellular canaliculi and tubulovesicular system of the parietal cells. These fucose residues were added in the trans-Golgi regions to the elongating chains. Additional fucose linked to the innermmost N-acetylglucosamine of the N-linked oligosaccharides was found in the chief cells, being incorporated in the cis-Golgi. The findings in the transitional cells corroborate the origin of the chief cells from the mucous neck cells.

Fates of the blastomeres of the 32-cell stage Pleurodeles waltl embryo

Cell fate of the blastomeres at the 32-cell stage in the Pleurodeles waltl embryo was analyzed by injection of rhodamine or fluorescein lysinated-dextran (RLDx or FLDx). At the tailbud stage, the progeny of each blastomere contributed to more than one germ layer with unequal distribution along the anteroposterior and dorsoventral axis. Such a regionalized positioning of the descendants of the 32-cell blastomeres was found in the neuroectoderm, the epidermis, the notochord, the somites, the lateral plate, and the endoderm, but not in the head mesenchyme, the pronephros, or the blood islands. Results of double labeling of juxtaposed blastomeres showed that cell mixing and rearrangement take place during organ formation. Results are compared with those of the 32-cell stage fate map in Xenopus and Rana and reveal the more restricted fate of 32-cell stage blastomeres in Pleurodeles germ layers.

Characterisation of secondary spermatocytes in the marbled newt (Triturus marmoratus)

Secondary spermatocytes in the marbled newt (Triturus marmoratus) were identified by means of cytophotometric quantification of nuclear DNA in the testicular lobules containing primary spermatocytes in advanced stages of the first meiotic division (from pachytene onwards) and newly formed spermatids. The nucleus of secondary spermatocytes has an intermediate size between that of primary spermatocytes and round spermatids and was characterised by the presence of abundant masses of dense chromatin and the absence of a nucleolus. At the prophase the chromatin masses were located at the periphery of the nucleus. The ultrastructural study revealed that the nuclear envelope displayed blebs and that the cytoplasm was very similar to that of primary spermatocytes including the presence of smooth endoplasmic reticulum whorls, multiple small dictyosomes, and a proacrosomal-like granule near the nucleus. This granule stained weakly with aqueous PTA and was observed in about 6% of secondary spermatocytes. Many of the mitochondria were grouped beneath the plasma membrane. Approximately 2% of these cells presented an axoneme which was not associated with other flagellar components.

Ultrastructure of the aging human testis

The ultrastructure of the progressive testicular involution with advancing age in men is reviewed. There is no definite age at which testicular involution begins, and the onset and severity of testicular lesions are subjected to pronounced individual variations. Hormone studies also indicate great individual variations, and subtle changes in both the testis and the pituitary develop progressively with age. Testicular size, sperm quality, and numbers of all germ cell types, Sertoli cells, and Leydig cells decrease with age. The volume occupied by the seminiferous tubules decreases, whereas that occupied by the testicular interstitium remains constant. The most frequent histological pattern of the aging testis is a mosaic of different seminiferous tubule lesions, varying from tubules with complete, although reduced, spermatogenesis, to completely sclerosed tubules. The tubules with complete spermatogenesis may show numerous morphological abnormalities in the germ cells, including multinucleation. Abnormal germ cells degenerate causing Sertoli cell vacuolation. These vacuoles correspond to dilations of the extracellular spaces resulting from the premature exfoliation of germ cells. Degenerating cells that are phagocytosed by the Sertoli cells give rise to an accumulation of lipid droplets in the Sertoli cell cytoplasm. The loss of germ cells begins with the spermatids, but progressively affects the earlier germ cell types, and tubules with maturation arrest at the level of the spermatocytes or spermatogonia are observed. The Sertoli cells show morphological abnormalities such as dedifferentiation, mitochondrial metaplasia, and multinucleation. Germ cell loss is associated with thickening of the tunica propria. When all seminiferous epithelial cells have disappeared, only an intensely collagenized tunica propria with myoid cells remains (sclerosed tubules). The Leydig cells progressively dedifferentiate with a decrease in the quantity of both smooth endoplasmic reticulum and mitochondria, together with an accumulation of lipid droplets, crystalline inclusions, and residual bodies, and formation of multinucleate cells. The development of tubular involution with age is similar to that observed after experimental ischemia, suggesting that vascular lesions may play an important role in age-related testicular atrophy.

Effects of photoperiod and temperature on testicular function in amphibians

Most amphibians present an annual testicular cycle characterized by a quiescent period (late autumn-winter) and a spermatogenic period (spring and summer). At the end of the period of spermatogenesis undifferentiated interstitial cells transform into steroid-secreting Leydig cells which regress in spring at the beginning of the new spermatogenetic cycle. The testicular cycle is controlled by the pituitary gonadotropin levels which are high in autumn and winter, low in spring and increase temporarily in the middle of summer. Photoperiod and temperature seem to be the most important external factors involved in the regulation of this cycle in many amphibian species since the colder the geographic area, the longer the quiescent period and the shorter the spermatogenic period. This suggests the occurrence of a potentially continuous cycle in these species, in contrast with that which occurs in other species having an endogenous rhythm of testicular function which is much less sensitive to environmental factors. Although the specific response to temperature can vary widely between species, the most frequent observation in amphibians with a potentially continuous cycle is that exposure to mild temperatures (15-20 degrees C, according to the spring temperatures of the different geographic areas) stimulates spermatogenesis even during the period of testicular quiescence. If this mild temperature is combined with a long photoperiod, complete spermatogenesis is attained. Experiments performed during the period of germ-cell proliferation (development from spermatogonia to round spermatids) indicated that low temperatures (below 11 degrees C) as well as short photoperiods (less than 8 h of light) hinder germ-cell proliferation. Moderately high temperatures (about 30 degrees C) do not impair this proliferation. In the newt Triturus marmoratus, it has been shown that an excessively long photoperiod (over 16 h) has the same effect as a short photoperiod. In this species eyes are not required for the testicular photoperiodic response. Photoperiod appears to have no effect on spermiogenesis (differentiation of round spermatids into spermatozoa), because once round spermatids are formed, spermiogenesis will occur even in total darkness. Mild temperatures seem to be necessary for spermiogenesis as well as for androgen biosynthesis because neither process will take place at extreme temperatures. Results on the effect of photoperiod in steroidogenesis differ between species.

The cycle of follicular and interstitial cells (Leydig cells) in the testis of the marbled newt, Triturus marmoratus (Caudata, Salamandridae)

Ultrastructural examination of the marbled newt (Triturus marmoratus) testis throughout the annual cycle revealed that during the period of testicular quiescence (November-February), primordial germ cells proliferate within cords of filament-rich epithelial cells that will become follicular cells (FCs). Fibroblast-like cells surround the FCs and form the lobule-boundary interstitial cells (ICs). During the period of germ cell development from primordial germ cells to round spermatids (March-June), the FCs surrounding the developing germ cells contain scanty cytoplasm with abundant rough endoplasmic reticulum and scarce filaments. With spermatid elongation (July-August), the FC size grows, its nucleus becomes irregularly outlined, and its cytoplasm displays abundant smooth endoplasmic reticulum, residual bodies, lipid droplets, and large vacuoles. After spermatozoon release by the FCs (August-September), the adjacent ICs increase their size and transform into Leydig cells with abundant smooth endoplasmic reticulum, mitochondria with tubular cristae, and lipid droplets. During the period of testicular quiescence (November-February), the Leydig cells undergo involution, eventually developing the morphological attributes of mesenchymal cells. Intermingled among these cells, cords of filament-rich cells are observed. During this period of the cycle, spermatozoon cysts supported by FCs are present. At the beginning of the germ cell proliferation period (March), these spermatozoa are released, and the adjacent ICs undergo a transformation into Leydig cells similar to those observed in August-September. Maturation and involution of ICs occur when testosterone levels are known to be rising and falling, respectively.

Annual changes in the number, testosterone content and ultrastructure of glandular tissue cells of the testis in the marbled newt Triturus marmoratus

The testes of 8 specimens of Triturus marmoratus were collected during each month of 1987 and processed for electron microscopy and light microscopy demonstration of testosterone (T) following the ABC (avidin-biotin peroxidase complex) method. According to their staining affinity for anti-T antibodies, the glandular tissue cells were classified as T-, T+, T++, and T and the annual changes in the numbers of these cell populations, as well as in the volume occupied by the glandular tissue, were calculated. The volume occupied by the glandular tissue increases from September to December; it begins to decrease in April and disappears from June to August. The glandular tissue is formed from the interstitial cells that surround the lobules containing differentiating germ cells. During the spermatogenic process, the interstitial cells do not show staining affinity for anti-T antibodies. In August-September, the interstitial cells around the lobules that have completed spermatogenesis become positively stained (T+) and form the glandular tissue when the spermatozoa leave the testis. The numbers of intensely stained cells in the glandular tissue (T++ and T ) increase from September to November; begin to decrease in December; disappear in January-February; increase again in March and decrease again in April until they disappear in June-September. The interstitial cells, before their transformation in glandular tissue, are ultrastructurally similar to fibroblasts. After their transformation these cells increase in size and develop abundant smooth endoplasmic reticulum, mitochondria with tubular cristae and lipid droplets. This morphological pattern is maintained in the glandular tissue from September to April in spite of the changes in staining affinity during this period.