Types Of Gland Cells Research Articles

Functional morphology of the tentacles and tentilla of Coeloplana bannworthi (Ctenophora, Platyctenida), an ectosymbiont of Diadema setosum (Echinodermata, Echinoida)

The tentacular apparatus of Coeloplana bannworthi consists of a pair of tentacles which bear, on their ventral side, numerous tentilla. Each tentacle extends from and retracts into a tentacular sheath. Tentacles and tentilla are made up of an axial core covered by an epidermis. The epidermis includes six cell types: covering cells, two types of gland cells (mucous cells and granular gland cells), two types of sensory cells (ciliated cells and hoplocytes), and collocytes, this last cell type being exclusively found in the tentilla. The core is made up of a fibrillar matrix, the mesoglea, which is crossed by nerve processes and two kinds of smooth muscle cells. Regular muscle cells are present in both the tentacles and tentilla while giant muscle cells occur exclusively in the tentilla. The retraction of the tentacular apparatus is an active phenomenon due to the contraction of both types of muscle cells. The extension is a passive phenomenon that occurs when the muscle cells relax. Tentacles and tentilla first extend slightly due to the rebound elasticity of the mesogleal fibers and then drag forces exerted by the water column enable the tentacular apparatus to lengthen totally. Once the tentacles and tentilla are extended, gland cells, sensory cells, and collocytes are exposed to the water column. Any swimming planktonic organism may stimulate the sensory cilia which initiates tentillum movements. Pegs of hoplocytes can then more easily contact the prey which results in a slight elevation of the nearby collocytes, the last being responsible for gluing the prey to the tentilla.

Dose-dependent induction of both pepsinogen-altered pyloric glands and adenocarcinomas in the glandular stomach of C3H mice treated with N-methyl-N-nitrosourea.

The dose‐response relation for the appearance of pepsinogen isozyme 1 (Pg l)‐altered pyloric glands (PAPG) and the related induction of adenocarcinomas were examined in male C3H mice given N‐methyl‐N‐nitrosourea (MNU) in their drinking water at the concentration of 120 ppm (group 1), 60 ppm (group 2), 30 ppm (group 3) or 0 ppm (group 4) for 30 weeks and then normal tap water. Animals were killed at weeks 10, 30 and 42. Adenomatous hyperplasias and adenocarcinomas were noted from week 30 and their induction was dose‐dependent at week 42. Almost all cells of pyloric gland cell type in those lesions had little or no immunohistochemically demonstratable Pg 1 content, as was also the case for the cells in PAPG, whose numbers per 100 normal‐appearing pyloric glands were found to be MNU dose‐dependent at all experimental time points. The numbers of PAPG at week 10 significantly correlated with the incidences of adenomatous hyperplasias and adenocarcinomas at week 42. Investigation of proliferation by immunohistochemical detection of bromodeoxyuridine (BrdU) labeling in the PAPG at week 10 demonstrated elevation (P <0.05) as compared to normal pyloric glands. Intestinal metaplasia was not a feature in the present experiment and the results suggest that in mice, PAPG might be a preneoplastic lesion involved in gastric chemical carcinogenesis.

Serotonergic Nervous System of Two Macrostomid Species: Recent or Ancient Divergence?

Serotonergic Nervous System of Two Macrostomid Species: Recent or Ancient Divergence?

Synaptic relationship of substance P-like-immunoreactive nerve fibers with gland cells of the anterior pituitary in the rat.

Our previous studies have proved the presence of substantial amounts of peptidergic nerve fibers in the anterior pituitary of human, monkey, dog, and rat, and synaptic contacts have been demonstrated on corticotrophs and somatotrophs in the dog. The present study is aimed at investigating the synaptic relationship between axons and gland cells in the rat. The substance P-like-immunoreactive nerve fibers were studied immuno-electron-microscopically. They were nonmyelinated and varicose. Typical synaptic contacts between the fibers and every type of the hormone-secreting gland cell could be identified, most frequently on lactotrophs. No synaptic contacts were found on the folliculo-stellate cell. The synaptic contacts were of asymmetrical type with clusters of small round clear vesicles at the presynaptic site and scattered large dense-cored vesicles. This pattern of synaptic relationships was markedly different from that in the dog. The presence of synapses in the anterior pituitary of the rat implies a direct neural regulation of certain cells and strongly supports our hypothesis of neural-humoral dual regulation of this gland.

Ultrastructure of the Genital Organs in the Interstitial Syllid Petitia amphophthalma (Annelida, Polychaeta)

Abstract The gonochoristic syllid Petitia amphophthalma is one of the truly interstitial polychaetes. P. amphophthalma does not show any epitokous modifications at maturity such as those that usually occur in syllids. The reproductive structures are unique: the male genital organs consist of a seminal vesicle in chaetigers 6–10, subdivided into a dorsal part tightly filled with spermatozoa and a ventral part with contents in different stages of spermatogenesis, one pair of sperm ducts and conspicuous gland cells situated in chaetigers 10 and 11. Their glandular secretions are discharged into the sperm duct together with those of other types of gland cells that form the duct. The oocytes develop freely within the body cavity of the females. Each of the fertile segments possesses a paired oviduct ending in a large ciliated funnel. Sperm ducts and oviducts are probably modifications of excretory organs; nephridia are absent in segments where gonoducts occur. A direct sperm transfer by lytic opening of the integument of the female and internal fertilization are inferred. Copyright © 1996 Published by Elsevier Science Ltd on behalf of the Royal Swedish Academy of Sciences

Quantitative immunocytochemical study of secretory protein expression in parotid glands of rats chronically treated with isoproterenol

Chronic treatment of mice and rats with isoproterenol (IPR) causes marked hypertrophy and hyperplasia of the salivary glands, and alters the expression of several secretory proteins. We used quantitative postembedding immunogold labeling to study the cellular responses in the rat parotid gland during daily (up to 10 days) injections of IPR and during recovery (up to 14 days) after cessation of IPR treatment. Labeling densities of acinar cell secretory granules with antibodies to amylase and protein SMG-B1 (cross-reactive with the rat homologue of Parotid Secretory Protein, PSP) fell to 10% of control levels after 8-10 IPR injections, then increased during recovery, paralleling previous biochemical determinations of changes in protein and mRNA levels. With antibodies to proline-rich proteins (PRP), labeling densities initially fell, then subsequently showed considerable variability, but never exceeded control levels. These results contrast with biochemical determinations showing a marked induction of PRP synthesis, and may have both immunological and structural explanations. Occasional intercalated duct cells located close to the acini underwent differentiation toward an acinar-like phenotype as a result of IPR treatment. After 1-2 IPR injections, the secretory granules of these cells labeled with antibodies to amylase and PRP. Subsequently, the granules appeared electron-lucent and were increased in size and number. These observations support earlier work, suggesting that intercalated duct cells may differentiate into other gland cell types.

Immunohistochemical Demonstration of Intestinal‐type Alkaline Phosphatase in Stomach Tumors Induced by N‐Methyl‐N′‐nitro‐N‐nitrosoguanidine in Rats

A potyclonal antibody against rat intestinal‐type alkaline phosphatase (I‐ALP) was generated and proven to be applicable immunohistochemically to paraffin‐embedded sections. Expression of I‐ALP in normal tissues, intestinal metaplasia and stomach tumors induced by N‐methyl‐N′‐nitro‐N‐nitroso‐guanidine (MNNG) was then investigated in five different strains of rats. Male SD (Crj:CD), Lewis (LEW/Crj), WKY (WKY/NCrj), Wistar (CrjrWistar) and F344 (F344/DuCrj) animals were given drinking water containing 100/μ/ml of MNNG for 30 weeks and were killed at week 50. Among the 5 strains, stomach adenocarcinomas were found most frequently in the SD case. The susceptibility of rats to induction of stomach carcinoma did not correlate with the development of intestinal metaplasias in each strain. Histochemical staining for mucin demonstrated all stomach tumors (adeno‐matous hyperplasias and well‐differentiated adenocarcinomas) to consist mainly of gastric type cells (pyloric gland cell and surface mucous cell types), with intestinal‐type tumor cells (goblet cell and intestinal absorptive cell types) being only occasional findings. Immunohistochemically, I‐ALP was strongly positive on the striated cell borders of small intestinal absorptive cells of the villus and on brush borders of epithelial cells of kidney proximal tubules. I‐ALP was also detected in the normal stomach, limited to the striated cell borders of absorptive cells of the upper one‐fourth of intestinal metaplastic glands. I‐ALP may thus be a useful marker for stomach tumor cells of intestinal absorptive cell type, indicative of maturation and differentiation. No stomach tumors consisting mainly of intestinal‐type cells were found, and therefore there was no suggestion of any derivation from intestinal metaplasias.

Ultrastructural study of frontal glands in Bothromesostoma personatum (Platyhelminthes, Typhloplanoida)

The frontal glands of Bothromesostoma personatum were examined using transmission electron microscopy. These glands have two types of rhabdoid gland cells; one type produces rhabdites and the other a different type of rod secretion (rhabdoids). The ultrastructure of the latter type is described, together with their origin. Long necks containing the rhabdoids emerge from the rhabdoid gland cell bodies and extend to the anterior end of the animal, where they release the rhabdoids. The rhabdoids are compared with the rhammites of other rhabditophoran species on the basis of their dye affinities, formation mechanism, and ultrastructure.

The Ultrastructure and Functional Morphology of a Captaculum in Graptacme calamus(Mollusca, Scaphopoda)

AbstractThe structure and function of the captaculum in Graptacme calamuswere studied using light microscopy, videomicrography, and transmission electron microscopy. Graptacme calamusutilizes a longitudinal ciliary band to transport small food particles along the outstretched filament. The head of the captaculum, which bears the alveolar indentation, contains a large ganglion, at least three types of gland cells, circular and longitudinal muscles, and connective tissue. It is likely that gland 1 secretes mucus which is used in the transport of food particles and that gland 2 secretes material which promotes adhesion of the alveolus to the substratum. The function of gland 3 is unknown. Critical observation of the captaculum surface revealed that the cilia of the alveolar region have truncated tips unlike those found on other regions of the captaculum. These alveolar cilia probably aid in the distribution of adhesive substance and in adhesion.

Expression of sialosyl-Tn in intestinal type cancer cells of human gastric cancers.

A sample of 219 primary stomach cancers, 143 advanced cancers and 76 early cancers were examined for mucin histochemical staining (the paradoxical concanavalin A method, the galactose oxidase-Schiff [GOS] reaction, and the sialidase-GOS reaction) and immunohistochemical reactivity (pepsinogen [Pg] I, Pg II, SH-9 and TKH-2). Gastric cancer cells were clearly classified according to mucin histochemistry into a gastric type, including mucus neck cell, pyloric gland cell and surface mucus cell types, and an intestinal type, including goblet-cell, and intestinal absorptive cell types. TKH-2 monoclonal antibody, which recognizes the mucin-associated sialosyl-Tn antigen, reacted with the mucin of goblet cells in both the normal small intestine and in the intestinal metaplasia of the stomach. Sixty-five of 106 (61%) differentiated adenocarcinomas and 76 of 113 (67%) undifferentiated adenocarcinomas had over 10% of their cancer cells positive for TKH-2. The TKH-2-positive cancers were primarily classified as a goblet-cell type by mucin-histochemical staining and the other immunohistochemical staining methods. Therefore, it is concluded that sialosyl-Tn is an excellent marker of small intestinal mucins and is indicative of a small intestinal type of differentiation in two-thirds of gastric cancers.

Further Ultrastructural Observations on the Epidermis of Phoronids: Phoronis australis and Phoronis hippocrepia

The epidermis of two species of phoronids, Phoronis australis and Phoronis hippocrepia, was studied using transmission electron microscopy and histochemical techniques. Results were compared with information available for Phoronis psammophila. The epidermis of each of the three species is similar with respect to certain cell types, namely supporting cells, fine-granule-containing cells, and four types of gland cells. These species differ, however, in abundance and distribution of each cell type. Differences may be related to different degrees of lubrication produced in various kinds of habitats (epifaunal, rocky, and sandy habitats). On the other hand, these differences may be related to burrowing activities in the three kinds of substrates. We conclude that possible correlations among structural patterns of the epidermis and various habitats primarily involve the relative abundance and distribution of gland-cell types along the trunk and ampulla. Phoronids are marine tube-dwelling invertebrates. The two species used for the present work, Phoronis australis Haswell, 1883, and Phoronis hippocrepia Wright, 1856, and a third species, Phoronis psammophila Cori, 1889, to which they are compared, build tubes in different substrates. P. psammophila lives in the intertidal and shallow subtidal zones (0-18 m depth) in sandy or muddy sediments, and its tube is covered by aggregated sediment particles (Emig, 1971; Fernandez et al., 1991); P. hippocrepia is found from the intertidal zone to 55 m depth, burrowing in rocks or empty shells or incrusting hard substrates; its tube is sinuous, without aggregated particles, except on the portion of the tube outside of the substrate (Emig, 1971; Emig & Bailey-Brock, 1987). P. australis occurs between the low-tide mark to 36 m depth and builds its tube in the tube wall of cerianthids, which may be considered a hard substrate (Emig, 1971; Emig et al., 1972). A detailed description of the epidermal cell types and their distributions along the trunk of P. psammophila was provided by Fernandez et al. (1991), who confirmed the statements of Pourreau (1979) relative to the role played by epidermal gland cells in tube construction. We have studied the ultrastructure of the epidermis of the trunk and ampulla of P. australis and P. hippocrepia in order to compare these species with P. psammophila and to describe possible relationships between the structure of the epidermis and habitat. I We thank Dr. C. C. Emig (Station Marine d'Endoume, Marseille) for the facilities needed to collect specimens of Phoronis hippocrepia and Drs. G. San Martin and E. Garcia Raso for kindly providing the specimens of Phoronis australis used in this study. This work was supported by a research grant (PB 860010) of the Comisi6n Interministerial de Ciencia y Tecnologia (CICYT). TRANS. AM. MICROSC. SOC., 112(4): 280-291. 1993. ? Copyright, 1993, by the American Microscopical Society, Inc. This content downloaded from 207.46.13.57 on Thu, 08 Sep 2016 06:10:38 UTC All use subject to http://about.jstor.org/terms VOL. 112, NO. 4, OCTOBER 1993 MATERIALS AND METHODS Individuals of both species studied were collected on the Mediterranean coast; Phoronis hippocrepia was found in a submarine cave near Marseille (France) at 10 m depth, and Phoronis australis was collected at 2-3 m depth in Almeria, SW coast of Spain, within tubes of Cerianthus sp. (Anthozoa). Specimens were fixed in 4% glutaraldehyde buffered with 0.1 M cacodylate in filtered seawater and postfixed in 1% osmium tetroxide in the same buffer. Tissue pieces then were dehydrated in an acetone series, stained en bloc in 2% uranyl acetate during dehydration, and embedded in Araldite via propylene oxide. Ultrathin sections were obtained with an LKB III ultramicrotome, stained with lead citrate, and examined with a Philips EM 201 electron microscope. For histochemical tests, specimens were fixed in neutral buffered formalin or Bouin's fluid and embedded in paraffin wax. Blocks were sectioned at 5-7 ,m. The following histochemical techniques were applied (details in Gabe, 1968; Lison, 1960; Pearse, 1968): 1. For characterization of mucopolysaccharides: periodic acid-Shiff (PAS), Alcian blue 8GX (AB) at pH 2.5 and 1.5; AB-PAS, and Toluidine blue (TB) at pH 4.2-1.5. 2. For proteins: Danielli's tetrazo reaction with or without previous treatment by DNFB (dinitrofluorobenzene), performic oxidation, benzoylation, and deamination.

Ultrastructure of the lophophoral tentacles in the genus Phoronis (Phoronida, Lophophorata)

The lophophoral tentacles of two phoronids, Phoronis psammophila and Phoronis hippocrepia, are described from an ultrastructural point of view. The tentacles are hollow structures, with an epidermis exhibiting supporting cells, sensory cells, and four types of gland cells, A, B1, B2, B3. The epidermis rests on a connective tissue layer, tubular in shape, enclosing a coelomic space lined by myoepithelial mesothelium (peritoneum). There is a single blood capillary in the tentacular coelomic cavity, attached to the frontal face of the tentacle, with contractile walls derived from the peritoneum. Both erythrocytes and amoebocyte-like cells occur inside the capillary. Differences between the tentacles of these two species and those of Phoronis australis, whose structure is already known, mainly concern the abundance and distribution of the epidermal gland cell types and are related to the burrowing and tube-building activities of these animals in different substrata.

Modulation of mammary carcinoma cell phenotype and keratin expression patterns by retinoic acid

Immunohistochemical and biochemical procedures were used to study the influence of retinoic acid (RA) on cellular expression and distribution of cytokeratins (CKs) in feline mammary carcinoma cells. These cells were grown in vitro as established cell lines (K248C and K266) and in vivo as xenografts in athymic mice. The results were compared with the distribution of CKs in normal feline mammary gland and in a series of invasive mammary carcinomas previously probed with a panel of monoclonal antibodies specific for individual CKs. Coexpression of CKs of both major mammary gland cell types (myoepithelial cells, MECs, CKs 5 14 positive, and luminal epithelial cells, LECs, CKs8 18 positive) by K248C and K266 cells, suggested a stem cell-like character of both cell lines. RA increased CK 19 expression in both cell lines and CK 19 was also present in tumors developed in nude mice from both RA untreated (CK 19 negative) and RA-treated (CK 19 positive) K248C and K266 cells. In addition, RA had cell line specific effects as well. RA treatment induced differentiation of K248C cells to more mature LEC-like cells and this change was accompanied by the loss of the MEC keratins CKs 5 14 . Under the same culture conditions however, RA treatment did not induce morphological changes in the K266 cell line and the expression of CKs 5 14 was not significantly reduced. These findings suggest that the modulation of CK 19 and CKs 5 14 expression observed in mammary carcinoma cells upon RA treatment might be regulated through different pathways.

Markers of surface mucous cell type human gastric cancer cells: Galactose oxidase‐Schiff reactive mucins, monoclonal antibody SH‐9 reactive mucins and cathepsin E

Cellular differentiation of gastric cancer cells allows the classification of cell type into surface mucous cell, pyloric gland cell, intestinal absorptive cell and goblet cell types by mucin histochemistry and pepsinogen (Pg) immunohistochemistry. Surface mucous cell differentiation of gastric cancers of each histologic type has previously been detected by the galactose oxidase-Schiff (GOS) reaction although this is not always positive in all cases. Mucus granules of surface mucous cells of normal gastric mucosa show an intense reactivity for SH-9 (monoclonal antibody against CA125-bearing antigenic molecule fragments). Cathepsin E is also expressed in the cytoplasm of surface mucous cells, weakly in absorptive cells of duodenal villi and occasionally in pyloric gland cells. Expression of SH-9 reactive mucin and of cathepsin E were therefore investigated as possible additional markers to distinguish between the gastric cancer cell type in 203 primary stomach cancers. SH-9 reactive mucin was found selectively in GOS positive cancer cells of surface mucous cell type and/or cancer cells unclassified by mucin histochemistry. These latter cells were therefore classified into the surface mucous cell category. Cathepsin E was found mainly in cancer cells of the GOS positive surface mucous cell type and occasionally, in intestinal absorptive and pyloric gland cell types. Galactose oxidase-Schiff, SH-9 and cathepsin E reactive or positive cancer cells were found in 145 (71.4%), 151 (74.4%) and 144 (70.9%), respectively, of the 203 primary stomach cancers investigated.

A morphological and histochemical study of the gland cells of a cercaria referable to the genus Acanthoparyphium (Trematoda: Echinostomatidae)

A cercaria referable to the genus Acanthoparyphium encountered in Cerithidea cingulata has been named as Cercaria bengalensis II. The present paper is the first report on the glandular complex in this genus. Our studies revealed the presence of different types of gland in the body and tail of Cercaria bengalensis II. Morphologically, three types of gland cell were apparent: penetration, cephalic and cystogenous glands. Histochemically, three types could be discerned as cystogenous glands: dorsal granular, dorsal vacuolated and ventral gland cells. Altogether five types of gland cell occurred. During the intraredial stages, a layer covering the tegument of the cercaria originated from the secretions of the ventral gland cells. In addition to this layer, a second layer underlying it was formed by secretions of the dorsal vacuolated cells. The secretions of the penetration glands contained proteins such as keratin, elastin- and collagen-like substances, and carboxylated and neutral mucopolysaccharides. The cephalic glands contained only keratinized proteins and traces of non-sulphated acid mucopolysaccharides. Dorsal granular cells had the task of secreting keratin, disulphides, sulphydryls, elastin- and collagen-like substances as protein components and also sulphated and carboxylated acid mucopolysaccharides and traces of neutral mucopolysaccharides. Dorsal vacuolated cells behaved like dorsal granular cells, but did not secrete neutral mucopolysaccharides. Disulphide-containing proteins, lipids and phospholipids were also present. The ventral gland cells consisted only of strongly sulphated acid mucopolysaccharides and neutral mucosubstances, with no proteins.

Pharyngeal and Gastrodermal Ultrastructure of Prorhynchus stagnalis Schultze, 1851 (Turbellaria, Lecithoepitheliata)

AbstractThe digestive tract of a freshwater Lecithoepitheliata turbellarian, Prorhynchus stagnalis, has been studied at the ultrastructural level. The buccal tube connecting the mouth opening to the pharynx is lined by an insunk epithelium, and is provided with two kinds of secretory cells. The bulbous pharynx itself, typical of the genus, is a highly muscular organ, also lined internally by an insunk epithelium; it also bears at least two different types of gland cells. Externally the pharynx is enveloped by a thin, flat epithelium. The gastrodermis consists of phagocytes and Minotian gland cells, as typical for most Tricladida. No ciliary covering was observed along the whole digestive system; instead, phagocytic cells have long microvillar projections. Preliminary attempts to follow the digestive process using external markers and cytochemical reaction for acid phosphatase were successful in demonstrating endocytic activity in the phagocytes. These data, besides being a contribution to morphology and systematics, also speak in favour of the general digestive theory of Turbellaria proposed by Jennings and serve as a starting point for experimental studies on intracellular digestion within the Lecithoepitheliata.

Observation on the composition and biosynthesis of egg wax lipids in the cattle tick, Boophilus microplus.

The biosynthesis of wax lipids by Gené's organ, the egg waxing organ in ticks, was investigated. Gené's organ, a complex dermal gland system, applies a superficial wax layer to the eggs during oviposition which prevents desiccation and is essential for egg viability. The detailed anatomy and histology of the three gland cell types are unambiguously described. Serial sectioning of ticks showed that all three gland cell types are capable of contributing to the egg wax. The wax synthetic ability of these three gland types was characterized. The composition of wax lipids extracted from the surface egg wax, and from the three types of wax gland dissected from ovipositing ticks, was analysed using thin-layer and gas-liquid chromatography. Injection of ovipositing ticks with radiolabelled acetate resulted in the incorporation of the label into wax lipids by gland cells of Gené's organ. The egg wax was a complex mixture of long-chain alkanes and fatty acid esters. The gland cells contained a greater proportion of shorter chain alkanes than were present in the egg surface wax. Some unsaturated long-chain fatty acids were present, and these were more abundant in the gland cells than in the surface wax of oviposited eggs, suggesting that oxidation occurs after oviposition. The results confirm that the tubular glands, acinar accessory glands and lobular glands of Gené's organ all contribute to the egg waxes, although the lipid components differed in relative abundance. The results are also consistent with alkane synthesis from fatty acids in Gené's organ by a chain-elongation-decarboxylation pathway.

LABRAL GLANDS OF LEPTESTHERIA DAHALACENSIS (BRANCHIOPODA: SPINICAUDATA): AN ULTRASTRUCTURAL STUDY

ABSTRACT The upper lip of Leptestheria dahalacensis contains 3 types of large, polymorphous, and polynucleate gland cells, forming 5 morphologically and topographically distinguishable glandular groups: 2 lateral (A and B) and 1 median (C). In each group the gland cells are arranged in pairs: several of A cells, 2 of B cells, and 1 of C cells. RER, mitochondria, and Golgi complexes are more or less variously shaped in the 3 types of gland cells. The secretion products have different appearances: vesicles, or bodies with dense or variously structured contents. Gland cells of groups A and B show wide intracytoplasmic lacunar areas, but only in the cytoplasm of B cells variously structured secretion bodies are visible close to such lacunar areas. In contrast, each of the 2 C cells surrounds an extracellular funnel-shaped space originating from a deep invagination of the distal part of these cells. Small epidermal cells delimiting a duct are associated with each pair of gland cells. Nerve fibers in contact with the 3 types of gland cells are also seen. The results of the ultrastructural study are discussed in light of the data available on the labral glands of other copepod and branchiopod crustaceans.

The epidermis of Phoronis psammophila Cori (Phoronida, Lophophorata): an ultrastructural and histochemical study

The principal cell types of the trunk epidermis of Phoronis psammophila are categorized and described on the basis of their ultrastructural and histochemical properties. There are seven cell types: uniciliated supporting cells with a well-developed microvillar layer, fine-granule-containing cells with distinctive finger-like processes that contain vesicles and extend into the microvillar layer, and five types of generalized gland cells distinguished mainly by the fine structure of their secretory granules. Gland cells lack cilia but possess intact basal body complexes within the cytoplasm in close association with the Golgi complex. This is an unusual feature for gland cells, and suggests that they may have recently evolved from more typical ciliated epithelial cells. The secretory product of the gland cells contains either acidic mucopolysaccharides, which are mostly sulfated, or neutral mucopolysaccharides and protein. The possible functions of these cell types are discussed. The supporting cells are presumably involved in direct uptake of nutrients and (or) the protection and cleaning of the epidermis. The fine-granule-containing cells may help the animal adhere to the tube, whereas the gland cells probably function in the secretion of the tube.

Calcium Adenosine Triphosphatase and Secretion of Koilin Membrane in the Gizzard of the Fowl

The localization of calcium adenosine triphosphatase (Ca(2+)-ATPase) was determined histo- and ultracytochemically in the gizzard gland cells of the adult domestic fowl. Surface and chief gland cells exhibited faint and inconstant basolateral activity in contrast to basal cells, whose basolateral cell membrane constantly showed deposition on the external side. Intracellular enzyme activity was localized on the luminal aspect of Golgi membranes in all types of gland cells. Lysosomes also reacted positive for Ca(2+)-ATPase. Neither membranes of secretory vesicles nor cortical cytoplasm of the secretory pole exhibited enzyme activity. From these results it is speculated that calcium is not essentially involved in the secretion of the koilin membrane in terms of storage of the secretory material, transport to the secretory surface and release into the lumen. Ca(2+)-ATPase activity rather seems to be related to differentiation and maturation processes and to intracellular storage of Ca2+.