Structural features of the epididymis in a dasyurid marsupial (Antechinus stuartii)

Summary The ductus epididymidis of the marsupial mouse Antechinus stuartii was divided into caput, corpus, and caudal regions using several constant morphological landmarks. Tubule diameter and epithelial height increased gradually from caput to cauda. In contrast, the surface area of the lumen of the ductus epididymidis increased to a maximum in the distal caput region, but decreased markedly in the distal cauda in association with characteristic changes in lumen shape (from circular to slit-shaped) and epithelial height. Epithelial cells of the ductus epididymidis were generally similar in structure to those described in other mammalian species. Principal and basal cells were common throughout the epithelium. Clear and mitochondria-rich cells were also identified, but occurred less frequently. Regional variations in cell ultrastructure were observed only in principal cells. Numerous vesicular inclusions occurred in the apical cytoplasm of cells in caput segments, membrane-bounded, electron-dense bodies were common in distal corpus regions, and a brush border of microvilli characterized the luminal surface of principal cells in caudal segments. Sperm index increased in the proximal caput, declined to basal levels in the distal caput and proximal corpus, and then increased to a maximum in segment 9 of the distal corpus and remained at about this level throughout the cauda epididymidis. Nuclear rotation, loss of cytoplasmic droplets, and other sperm maturational changes were observed along the epididymis. Discarded cytoplasmic droplets collected in large masses interspersed between aggregates of spermatozoa throughout the distal regions of the duct. There was no evidence of phagocytosis by principal cells of cytoplasmic droplets. The epididymis of A. stuartii differs from that of other mammals. The unusual caudal region, which has little storage capacity for sperm, is an unusual adaptation in a species in which the male is known to be polygamous.     

Isolation and cell culture of the epithelial cells of cauda epididymidis of the bull

A simple and rapid method has been described to isolate the epithelial cells of cauda epididymidis of adult bull. Perfusion of the lumen of the cauda epididymidis with 1 mg/ml collagenase in calcium- and magnesium-free Hank's balanced salt solution and incubation of the tissue at 37 degrees C for 90 min releases the principal and basal cells into the lumen. Several individual epithelial cells and cell aggregates without the contamination of stromal or smooth muscle cells can be flushed out at the end of incubation. The isolated epithelial cells, suspended in Dulbecco's medium with 10% horse serum, attach to plastic dishes within 3 h after seeding the cells and proliferate to form a monolayer in approximately 8-12 days. The electron microscopic study and immunostaining of the cultured epithelial cells indicate that the cultured cells are principal cells. The basal cells of the intact cauda epididymidis of bull show within their cytoplasm the presence of varying amounts of "lipid-like" material often closely associated with whorls of membrane.     

Morphology of the epithelium of the extratesticular rete testis, ductuli efferentes and ductus epididymidis of the adult male rabbit

The fine structure of the epithelium lining the extratesticular rete testis, ductuli efferentes and ductus epididymidis of the rabbit has been investigated. In the ductuli efferentes the epithelium is composed of two cell types, principal cells and ciliated cells. The latter type is distinguished from principal cells by the presence of cilia projecting into the lumen and the position of the nucleus in the apical half of the cell. Principal cells in this segment are characterized by micropinocytotic vesicles on the surface plasma membrane and a variety of small dense bodies scattered throughout the cytoplasm. In the ductus epididymidis basal cells replace ciliated cells as the second cell type, but differences between various segments of the epididymis are related to the fine structure of the principal cells. In the proximal caput epididymidis (Nicander's region 1) the principal cells are tall with long microvilli. They typically contain a small Golgi apparatus and a cluster of dense bodies adjacent to the nucleus. In the distal caput epididymidis (Nicander's regions 2-5) the apical cytoplasm of principal cells is filled with numerous micropinocytotic vesicles and large multivesicular bodies; these features are interpreted as signs of absorptive activity. The multivesicular bodies are absent from the cytoplasm of principal cells in the corpus epididymidis (Nicander's region 6) and, instead, numerous elements of smooth endoplasmic reticulum, a large Golgi apparatus, lipid droplets and dense bodies characterize principal cells in this segment. Towards the proximal cauda epididymidis (Nicander's region 7), the number of dense bodies (lysosomes) in the cytoplasm increases considerably. In the globose cauda (Nicander's region 8), the principal cells are reduced in height, and in addition to the features described in region 7, are characterized by a concentric array of rough endoplasmic reticulum in the basal cytoplasm. These observations are discussed in relation to the role of the epididymis in promoting the maturation and survival of spermatozoa.     

Morphometric analysis of coated pits and vesicles in the proximal and distal caput epididymidis

A morphometric analysis of coated and uncoated structures found in the apical portion of principal cells from both the proximal and distal caput epididymidis has been carried out. Almost all endocytic, coated vesicles are found within 1 micron of the luminal surface of principal cells and the volume fraction of these and of uncoated vesicles is much greater in the proximal caput epididymidis. A serial section analysis indicated that many coated "vesicles" are tangentially sectioned coated pits and that a complex network of interconnected vesicular and tubular structures exists in the apical cytoplasm. Efferent duct ligation has no effect on the number of size of large coated and uncoated vesicles in either the proximal or distal caput epididymidis, indicating that substances delivered to principal cells from the lumen are not required to maintain the endocytic machinery. However, this treatment does result in a considerable increase in the number of large coated vesicles associated with the basal surface of principal cells from the proximal but not the distal caput epididymidis. The volume fraction of small, presumably exocytic, coated vesicles is significantly greater in the apical cytoplasm of cells from the distal caput epididymidis in control animals. Efferent duct ligation results in a significant increase in the volume fraction of these vesicles in the proximal but not distal caput epididymidis. These results show that there are marked differences in structure among principal cells from these two regions of the epididymis and that this may reflect differences in control and function.     

Ultrastructure of the perfused rat epididymis: Effect of luminal sodium ion concentration

Summary The appearance of the rat epididymal epithelium changed when it was perfused in vivo through the lumen with unphysiologically high sodium ion concentrations; dilatation of intercellular spaces (ICS) at threshold concentrations of 30mM-Na⁺ in the cauda and about 55mM-Na⁺ in the corpus was associated with absorption of water from the lumen. Despite the distended ICS, junctional complexes appeared intact, and their integrity was confirmed by the exclusion of luminal horseradish peroxidase (HRP) from the ICS, and by demonstrating that circulating [³H]inulin did not enter the lumen. Smooth ER and lipid droplets in the principal cells of the corpus epididymidis were well maintained, and the preservation of granular ER in principal cells of the cauda epididymidis lent morphological support to the continued secretion of protein in this segment. However, occasional distension or involution of inner Golgi cisternae was evident in principal cells after 3–6 h perfusion. In contrast to multivesicular bodies of principal cells, the apical and basal vacuoles characteristic of clear cells changed in size with different perfusing solutions. When low Na⁺ concentrations were perfused large translucent vacuoles were frequently found in the apical cytoplasm of clear cells in the corpus and cauda epididymidis, and filled vacuoles became larger and showed a decrease in content density in the cauda epididymidis. These large vacuoles were absent from tissue perfused with high Na⁺ concentrations. Normal pinocytotic activity of both cell types was demonstrated by perfusing HRP which was taken up by the normal route in principal cells, with some transfer to the Golgi cisternae. By far the most HRP was accumulated in clear cell vacuoles irrespective of the composition of the perfusing solution.     

Ultrastructural localization of PGP 9.5 and ubiquitin immunoreactivities in rat ductus epididymidis epithelium

Summary The distribution of protein gene product 9.5 (PGP) and ubiquitin in the spermatozoa and epithelial cells in the different regions of the rat duetus epididymidis (proximal caput, distal caput, corpus and cauda) was studied by Western blotting analyses and electron microscopical immunogold labelling. Western blotting analyses showed that the PGP immunoreactive band was very intense in the caput and cauda epididymidis and almost irrelevant in the corpus, while the ubiquitin immunoreactive band was intense in the distal caput and cauda. No ubiquitin immunoreactive band was observed in the proximal caput and only a very weak band was seen in the corpus. The results of electron microscopical immunogold labelling varied from one epididymal region to another. The proximal caput epididymidis presented immunoreaction to PGP in the rough endoplasmic reticulum, cytosol, mitochondria and microvilli of most principal cells, and in the cytosol, rough endoplasmic reticulum and mitochondria of most basal cells. No ubiquitin immunoreaction was observed in this epididymal region. In the distal caput epididymidis, PGP immunoreactivity was detected in some principal and basal cells in the same intracellular locations as described in the proximal caput. In this region, ubiquitin immunoreactivity appears in the apical cytosol and mitochondria of principal cells. The corpus epididymidis showed no immunoreaction to PGP or ubiquitin. In the cauda epididymidis, immunostaining to PGP was observed in most clear cells and in isolated principal cells. The intracellular location of PGP in both cell types was the cytosol, mitochondria and microvilli. Ubiquitin immunoreactivity was detected in the perinuclear cytosol and mitochondria — but not in the digestive vacuoles — of some clear cells. Scanty ubiquitin immunolabelling was also found in the microvilli, cytosol and mitochondria of some principal cells. The head of the spermatozoa present in the ductal lumen in all epididymal regions immunoreacted intensely to PGP. Ubiquitin was detected in the intermediate piece and residual cytoplasm of intraluminal spermatozoa present in the corpus and cauda epididymidis. These findings suggest that a non-ubiquitinated PGP irnrnunoreactive protein is secreted by the principal cells in caput epididymidis and binds the spermatozoon heads. It is possible that the clear cells of the cauda epididymidis secrete the ubiquitin that binds to spermatozoon tail.     

Cytochemical and ultrastructural characteristics of the lining epithelium of the distal part of the epididymis in hamsters (Mesocricetus auratus)

In the terminal segment of the hamster epididymidis there was some evidence of micro-merocrine protein secretion a the level of the principal cells and clear evidence of granular secretion in the light cells, presumable of glycoproteins. The PAS and protein cytochemistry reactivities observed in both these cells, of the ductus epithelial lining, but especially in the light cells, are suggestive of mucopolysaccharides and protein complexes synthesis and secretion. This secretion is carried out to the epididymal epithelium from the lumen and luminal content. A complex of small vacuoles and vesicles appeared to form from the Golgi complex is showed in the principal cells. It was suggested that this complex may represented merocrine secretory vacuoles and vesicles in these cells. Dense granules, at the TEM level, are observed in all the cytoplasm of the light cells, with correspondence to similar PAS-positive granules observed in these cells, at the light microscope level. These granules, at the TEM level, are actually secreted to the epididymal duct lumen, by the apical cytoplasms of the light cells. Signs of absorption were suggested to the principal and light columnar cells through the ultrastructural observations of micropinocytosis, apical multivesicular bodies or great membrane-bounded vacuoles in the adluminal cytoplasms.     

Sexual characteristics and spermatogenesis in males of the parthenogenetic gecko Lepidodactylus lugubris (Reptilia, Gekkonidae)

Obligately parthenogenetic lizards usually are all-female populations of hybrids producing diploid oocytes by premeiotic endomitosis and quasi-normal meiosis. In an all-female strain of the gekkonid lizard Lepidodactylus lugubris several phenotypic males arose spontaneously. The sexual characteristics of these males were studied using light and electron microscopy and compared with normal males of the bisexual genus Lygodactylus. Emphasis was layed on morphology of seminiferous tubules, occurrence of spermatogenic stages and ultrastructure of spermatozoa. The phenotypic males possessed preanal pores filled with secretions and a sexual nephric segment which were exactly the same as in normal, reproductively active males. In the testes, density and morphology of non-spermatogenic cell types, the Leydig and Sertoli cells, indicate a normal production of testicular testosterone and a normal function of the blood-testis barrier, respectively. Both in the normal and the phenotypic males, all meiotic cell types of spermatogenesis can be recognised in the seminiferous tubules and are apparently identical, indicating a normal meiosis without impairment in the phenotypic males. In contrast, the differentiation process of spermatids is markedly disturbed in the phenotypic males of L. lugubris. In the normal male, spermiogenesis results in mature spermatids and spermatozoa with small elongated nuclei, an acrosomal complex, and a flagellar tail possessing one axoneme. Spermatozoa fill both the lumen of most seminiferous tubules and the lumina of ductus epididymidis and ductus deferens. In the phenotypic male, spermiogenesis results in seemingly normal spermatids and in spermatozoa with large, non-elongated, deformed nuclei and/or irregular tails possessing more than one axoneme. Both the lumen of most seminiferous tubules and the lumina of the ductus epididymidis and the ductus deferens contain relatively few spermatozoa. We suggest that the phenotypic males inherited the ability for a premeiotic endomitosis from their all-female ancestral lineage. While in females this leads to quasi-normal meiosis and diploid oocytes capable of development, the small nuclei of the spermatozoa are unable to contain a diploid set of chromosomes. Because of the high amount of deformed spermatozoa and possibly uncontrolled loss of genetic material in structurally normal, but aneuploid spermatozoa we conclude that these otherwise perfect males are infertile, thus constituting another example of gametic sterility.     

Role of epithelial clear cells of the rat epididymis in the disposal of the contents of cytoplasmic droplets detached from spermatozoa

Upon release from the seminiferous epithelium, spermatoza show a small droplet of cytoplasm attached to the neck region. During transit of spermatozoa in the caput epididymidis, this cytoplasmic droplet migrates along the middle piece of the flagellum. In the corpus epididymidis, the droplet shows a lateral displacement, while in the cauda epididymidis it detaches from the spermatozoon. In the electron microscope, cytoplasmic droplets attached to spermatozoa were seen to contain numerous, short, straight or C-shaped, flattened membranous elements referred to as lamellae, small vesicles, and small particles (35-nm diameter) with a diffuse wall showing no apparent unit membrane. The lamellae were stacked closely on one another or arranged in a loose array. Structurally as well as cytochemically, with different cytochemical markers, the lamellae and vesicular elements failed to show any evidence of being components of the Golgi apparatus or elements of the endoplasmic reticulum. The lamellae, vesicular elements, and 35-nm particles were also seen free in the lumen of the corpus epididymidis but were especially prominent in the cauda epididymidis at a time when droplets were being released from spermatozoa. The lumen of the epididymis, as spermatozoa passed from the caput to the cauda epididymidis, was also noted to acquire progressively a flocculent background material. The epididymal epithelium is composed predominantly of principal and clear cells. The endocytic activity of clear cells was examined in rats at different time intervals after a single injection of cationic ferritin into the lumen of the cauda epididymidis. At 2 min the tracer was bound to the microvilli of these cells and was also observed within large coated and uncoated pits, subsurface coated vesicles, and numerous subsurface small uncoated vesicular membranous elements (150-200-nm diameter). At 5 min, in addition to the above structures, the tracer was present in endosomes, while at 15 and 30 min, pale and dense multivesicular bodies appeared labeled, respectively. At 1 and 2 hr, but more so at 6 hr large dense membrane-bound bodies identified cytochemically as secondary lysosomes became labeled. All of the above endocytic structures were also seen to contain the 35-nm particles, flattened or vesicular membranous profiles, and a fine flocculent background material reminiscent of those seen free in the lumen or found in cytoplasmic droplets attached to spermatozoa. (ABSTRACT TRUNCATED AT 400 WORDS)     

Immunocytochemical localization of alpha-lactalbumin in the male reproductive tract

The immunocytochemical localization of the milk protein alpha-lactalbumin in the male reproductive tract is described. Using a primary antiserum raised against highly purified rat milk alpha-lactalbumin, specific staining was consistently shown in the supranuclear Golgi region of the principal cells of the proximal caput epididymidis but only occasionally in epithelial cells from other regions of the duct. Staining was also found in the epididymal lumen and associated with spermatozoa. This luminal staining persisted throughout the distal caput, corpus and cauda epididymidis. Staining was rarely associated with spermatozoa in the efferent ducts and initial segment. Alpha-lactalbumin immunoreactivity was also detected in the seminiferous epithelium. Staining was confined to the Golgi-acrosome region of spermatids. These results indicate that an alpha-lactalbumin-like molecule, or molecules, is present in the male reproductive tract and that it is localized specifically in principal cells from the proximal caput epididymidis and germ cells from the seminiferous epithelium.     

Immunocytochemical localization of the major glycoprotein of epididymal fluid from the cauda in the epithelium of the mouse epididymis

Summary The most abundant protein in fluid from the mouse cauda epididymidis, designated CP 27, is a glycoprotein that migrates at approximately 27000 daltons on SDS-polyacrylamide gels. Samples of CP 27 were isolated by preparative gel electrophoresis and were used to raise a guinea-pig polyclonal antiserum, which reacted with a single band on western blots of caudal epididymal fluid. This antiserum was used for immunocytochemical localization of CP 27 in histological sections of mouse epididymis using the peroxidase-antiperoxidase and protein A-gold methods. The most proximal staining with anti-CP 27 was in segment 6 of the distal caput epididymidis, where the lumen and a portion of the supranuclear cytoplasm of principal cells were stained. In contrast, in the distal corpus and cauda epididymidis (segments 8–11), there was pronounced staining of the luminal contents, stereocilia, and scattered cells identified as the light cells of the epididymal epithelium. Although CP 27 was found in the epididymal lumen of all segments distal to segment 6, the intensity of staining appeared to decline distally in the cauda epididymidis. Control sections exposed to pre-immune serum instead of anti-CP 27 showed no reaction. The results suggest that CP 27, the major glycoprotein of cauda epididymal fluid, is synthesized by principal cells of segment 6 of the distal caput epididymidis. CP 27 may be among the substances absorbed from the lumen by the light cells of the distal epididymis.     

Unit gravity sedimentation separation of cells comprising the caput epididymidis of the rat

Summary Cells from the rat caput epididymidis were separated by unit gravity sedimentation. Purest 12-ml fractions contained 88–95% basal cells or 64–76% principal cells. Ultrastructure of separated cells was similar to that of cells in intact tissue. Viability of separated cells was excellent as determined by dye exclusion tests and cellular ATP content. By combining fractions pools containing 4.0±0.9 × 10⁶ cells (86±8% basal cells) and 1.4±0.4 × 10⁶ cells (56±7% principal cells) were obtained. Thus, studies on the function of basal and principal cells from the rat caput epididymidis should be possible.This research was supported by NIH Grant HD-07244 and was authorized for publication as Paper No. 5231 in the Journal Series of the Pennsylvania Agricultural Experiment Station. We thank Mrs. J. Eastman for expert technical assistance     

An autoradiographic study of macromolecular syntheses in the epithelium of the ductus epididymidis in the mouse

Summary Glycoprotein dynamism in the mouse epididymis was studied by means of histoautoradiography after injection of l-fucose-1-³H. The label was detected, at thirty minutes p.i., in the area occupied by Golgi apparatus in the epithelial cells. At 4 h p.i. the label was already present in the lumen of ductus epididymidis. At this time interval, the luminal labelling was highest in the initial segment of the epididymis and decreased against the more distal segments considerably.At ten days p.i. very high labelling was detected in the luminal contents in the terminal segment of the ductus epididymidis and in ductus deferens, the labelling in the proximal segments of the epididymis being much lower. These observations suggested a wave of labelled glycoprotein in epididymal plasma passing through the epididymis after a fucose pulse.Higher labelling was detected in so-called clear cells than in the neighboring principal cells.Association of the labelled material was seen in epididymal and uterine spermatozoa, mostly in sperm tail region.     

Histological effects of androgen deprivation on the adult chimpanzee epididymis

Primate sperm acquire functional maturity, including vigorous forward motility and the ability to fertilize an ovum, as they transit the unique, regional microenvironment of the epididymal lumen. Several proteins secreted into this luminal fluid are epididymal-specific and androgen-dependent, and thus contribute potentially to sperm maturation. For the adult male chimpanzee, we report the effects of GnRH antagonist-induced androgen deprivation on the histology of the epithelia and interstitium composing the ductuli efferentes, ductus epididymis, proximal ductus (vas) deferens. After 21 days of androgen deprivation, epididymal tissues exhibit characteristic atrophic changes, including cellular disorganization, degradation, and loss of structures. Androgen-deprived cytoplasm is differentially and characteristically disrupted, vacuolated, and reduced in volume, resulting in decreased epithelial height and loss of stereocilia. Most principal cell nuclei appear hyperchromatic, smaller in size, more irregular in outline, and disordered in arrangement, while others appear swollen and vacuolated. Apical cells of the efferent ducts and the basal cells and microvillar borders of the ductus epididymis seem minimally affected by androgen deprivation. Such histologically differential responses suggest correspondingly that androgen is differentially essential to the maintenance of the epididymis and thus to normal functioning of the component tissues. Therefore, epididymal epithelia directly and their secretions indirectly are differentially androgen-dependent.     

Olfactory metamorphosis in the coastal tailed frog Ascaphus truei (Amphibia,Anura, Leiopelmatidae)

The structure of the olfactory organ in larvae and adults of the basal anuran Ascaphus truei was examined using light micrography, electron micrography, and resin casts of the nasal cavity. The larval olfactory organ consists of nonsensory anterior and posterior nasal tubes connected to a large, main olfactory cavity containing olfactory epithelium; the vomeronasal organ is a ventrolateral diverticulum of this cavity. A small patch of olfactory epithelium (the “epithelial band”) also is present in the preoral buccal cavity, anterolateral to the choana. The main olfactory epithelium and epithelial band have both microvillar and ciliated receptor cells, and both microvillar and ciliated supporting cells. The epithelial band also contains secretory ciliated supporting cells. The vomeronasal epithelium contains only microvillar receptor cells. After metamorphosis, the adult olfactory organ is divided into the three typical anuran olfactory chambers: the principal, middle, and inferior cavities. The anterior part of the principal cavity contains a “larval type” epithelium that has both microvillar and ciliated receptor cells and both microvillar and ciliated supporting cells, whereas the posterior part is lined with an “adult‐type” epithelium that has only ciliated receptor cells and microvillar supporting cells. The middle cavity is nonsensory. The vomeronasal epithelium of the inferior cavity resembles that of larvae but is distinguished by a novel type of microvillar cell. The presence of two distinct types of olfactory epithelium in the principal cavity of adult A. truei is unique among previously described anuran olfactory organs. A comparative review suggests that the anterior olfactory epithelium is homologous with the “recessus olfactorius” of other anurans and with the accessory nasal cavity of pipids and functions to detect water‐borne odorants. J. Morphol. 2011. © 2011 Wiley Periodicals, Inc.     

Testis and epididymis of the Indian wall lizard (Hemidactylus flaviviridis): effects of flutamide on FSH and testosterone influenced spermatogenesis, Leydig cell, and epididymis

To determine the separate spermatogenic actions of FSH and testosterone, adult male lizards Hemidactylus flaviviridis with recrudescent testes were administered the non-steroidal antiandrogen flutamide either alone or in combination with FSH or testosterone, and the histology and histochemistry of the testes and ductus epididymides were studied. Flutamide-treated animals displayed a marked hypertrophy of Leydig cells. A few spermatids were also seen in testis of more than half the animals treated with flutamide. Flutamide also produced a significant increase of primary spermatocytes; no spermatids were observed in controls. A significant inhibition of spermatogenesis was noted in lizards treated either with testosterone alone or in combination with flutamide. Ovine FSH treatment caused a significant stimulation of spermatogenesis, as indicated by the increase of primary and secondary spermatocytes and the transformation of secondary spermatocytes into spermatids or, in a few cases, into spermatozoa. A considerable depletion of sudanophilic lipid and moderate delta 5-3 beta-hydroxysteroid dehydrogenase activity was noted in the Leydig cells of FSH-treated animals indicating enhanced steroidogenesis. Similar results were obtained when lizards were treated with flutamide + FSH. The effects of simultaneous treatment of flutamide with FSH or testosterone on ductus epididymidis revealed that flutamide markedly inhibited the epithelial cell height and lumen diameter with a loss of luminal content when compared to FSH or testosterone-treated lizards.     

Transcytosis in the epididymis studied by local arterial perfusion

Summary The transport of protein across the cells of the epididymal epithelium was studied using horseradish peroxidase. Transient vascular perfusion of the epididymis of the rat and golden hamster was achieved by pulsatile retrograde infusion into the testicular artery. Peroxidase was found in the interstitium and in the epithelium, located in vesicles, vacuoles and multivesicular bodies of principal, clear and apical cells. Similar findings were obtained in mice after systemic injection of the tracer. In the rat, discharge to the lumen was confirmed by the appearance of enzyme activity in luminal fluid from the caput epididymidis after local injection. The extent of transport amounted to no more than what has been considered leakage in physiological experiments, and the time-course of appearance complemented that found by electron microscopy. The level of transcytosis after pulsatile administration of peroxidase in vivo, as judged from the occurrence of tracer in the epithelium, was much less than that obtained during constant immersion in vitro. The protein was present in multivesicular bodies of principal cells and in vesicles of clear cells at short times after presentation in vitro, when it could not have arrived by endocytosis from the lumen. This suggests that routing of basal endocytic vesicles to the lysosomal apparatus occurs.     

Observations on the development of the foliar secretory cavities of Porophyllum lanceolatum (Asteraceae)

The lipophilic secretory cavities observed in the leaf of Porophyllum lanceolatum (Asteraceae) are scattered throughout the lamina and around its crenate margins. In the young leaf the cavities are initiated, and their development completed, while the surrounding tissues are still at early stages of differentiation. The cavity lumen has a lysigenous origin. Cell lysis, expansion of the developing leaf and, probably, the pressure exerted by the accumulation of secretory products, are believed to account for the gradual enlargement of the lumen. Concomitantly with ctll disintegration, which occurs throughout development, divisions take place in all cells of the gland. A mature cavity has a multilayered epithelium. Histochemical tests for RNA, proteins, phenolics and pectic polysaccharides revealed intense staining of the content of the epithelial cells in the early stages of cavity development, and a decrease in staining towards its maturity. Staining for lipids is intense in all developmental stages. Tests on the material observed in the lumen of mature cavities, show positive results for lipids, pectic polysaccharides and phenolics.