In vitro toxic effects of certain antibiotics on the fibroblasts of two children with I-cell disease

Six antibiotics, pefloxacin (Peflacine), fosfomycin (Fosfocine), teicoplanin (Targocid), vancomycin (Vancocine), ceftazidime (Fortum), piperacillin (Piperilline), that may be used as a systematic coverage during bone marrow transplantation have been tested on dermal fibroblasts of one control subject and two I-cell disease patients, along with five subcultures, corresponding to 5 weeks of culture. The possible toxicity of these molecules was assessed. The evaluation of lysosomal enzyme sphingomyelinase activity, detection of free intracellular cholesterol and the light- and electron-microscopic examination of treated cells were used as measures of metabolic interference and cytotoxicity. Our study shows that despite a lack of any metabolic sign of interference (no modification in enzyme activity, no increase in free intracellular cholesterol), all the antibiotics tested induced a cytotoxic effect which was notably amplified in the I-cell populations. This may be due to the lysosomal lipid storage of these cells which modifies the relationship between the antibiotic and the cell by inducing a different kind of lipid-antibiotic interference.     

Age-related changes in morphology and secretory responses of male rat lacrimal gland

This study investigates the differences in the outward appearance and morphology of lacrimal glands, the morphology within the lacrimal acinar cells and the secretion of protein from acinar cells of young (3-5 months) and aged (20 and 24 months) male rats. The appearance of the glands, as seen by the naked eye, differed between the three age-groups. The lacrimal gland of young animals was a smooth pink tissue, while the tissue from aged animals appeared lobular and white in colour, thought to result from infiltration of fatty/connective tissue. Glands from 24 month old animals had a more pronounced lobular appearance than the glands from 20 month old animals. Light microscopy studies revealed that as the animals aged there was evidence of progressive morphological changes. These changes included thickening of the connective tissue sheath, chronic inflammation with increased infiltration by mast cells, patchy destruction of ductal and vascular tissues, enlargement of lacrimal ducts, luminal swelling of the acini, and changes in acinar type. Electron microscopy (EM) studies revealed the presence of 3 types of acini in the rat lacrimal gland: acini which contained only protein secretory granules (serous acini), acini which contained protein and mucous secretory granules (seromucous acini), and acini which contained only mucous secretory granules (mucous acini). In young glands the majority of acini were serous with a few seromucous acini and even fewer mucous acini. In aged glands there were significant reductions in serous acini (ANOVA; P < 0.01) when compared to the young glands. In 20-month-old glands, there were marked increases in the percentage occurrence of seromucous acini, while in 24 month old glands, there were large increases in the relative number of mucous acini. Qualitative EM studies demonstrated that the typical acini from young glands contained numerous protein secretory granules. Ageing was associated with a progressive loss of protein (serous) secretory granules. Furthermore, marked changes and patchy destruction of the endoplasmic reticulum and Golgi apparatus were observed in acini of glands from aged rats when compared to acini of glands from young rats. Measurement of total protein output from acini revealed a significant (Student's t-test, P < 0.05) decrease in protein secretion from aged glands compared to glands from young animals. These results suggest that not only is there considerable structural damage, chronic inflammation and mast cell infiltration to the lacrimal gland with ageing, but also possible redifferentiation of acini from serous to seromucous and then to mucous acini. Furthermore, the results also suggest a reduction or an inability of the acini to synthesise and to secrete protein from glands of aged animals compared to glands of young rats. All of these changes appear to occur more rapidly as the rats mature between 20 and 24 months. These findings provide a morphological basis to explain the phenomenon of reduced tear/protein secretion with ageing.     

Ultrastructure and lectin cytochemistry of the cloacal pelvic glands in the male newt Triturus marmoratus marmoratus

The cloacal organ of Salamandridae species contains four glands: pelvic, dorsal, ventral, and Kingsbury's glands. Pelvic glands have been studied only by light microscopy with conventional methods, and consist of multiple tubular serous glands with a prismatic epithelium which contains numerous PAS positive secretory granules. The present report is an ultrastructural and lectin cytochemistry characterization of the pelvic glands of Triturus marmoratus marmoratus throughout the reproductive cycle. Our methods consisted of conventional electron microscopy, and colloidal-gold lectin cytochemistry of the following lectins: WGA, ConA, LcA, UEA-I, PNA, SBA, and HPA. In the prereproductive period, the glands showed a tall epithelium which consisted of two cell types, dark and clear cells, surrounded by elongated, myoepithelial cells. Both dark and clear cells showed the ultrastructural characteristics of secretory cells, and exhibited many secretory granules in the apical cytoplasm. Areas showing densely packed, degenerating cell organelles--which were not surrounded by membrane--were observed in the dark cells whereas the clear cells showed large heterolysosomes. In the postreproductive period the number of secretory granules decreased, the rough endoplasmic reticulum was less developed, and areas of degenerating organelles were absent. In addition, small basal cells appeared. The results of the lectin histochemistry study were similar in both reproductive periods. In the epithelial cells, the rough endoplasmic reticulum, the Golgi complex, and secretory granules exclusively labeled to ConA. In all cell types, the nuclei reacted to all lectins while the cytosol only reacted to LcA lectin. The ultrastructural and histochemical characteristics of the pelvic glands of T. marmoratus suggest that these glands could be homologous to the mammalian seminal vesicles and prostate.     

Gap junction involvement in secretion: the pancreas experience

1. Gap junctions and junction-mediated cell-to-cell communications are obligatory features of gland cells, whatever their secretory product is. 2. Studies on pancreatic islets and acinar cells indicate that cell-to-cell communication via gap junction channels is required for proper biosynthesis, storage and release of both insulin and amylase. 3. However, the endocrine and exocrine portions of the pancreas show opposite connexin (Cx) and coupling changes in relation to the activation and inhibition of their secretory functions. 4. These differences may be accounted for by the expression of Cx43 in pancreatic islets and of Cx26 and Cx32 in pancreatic acini. This alternative expression of connexin isoforms is also found in several other endocrine and exocrine glands. 5. These observations indicate that connexin-made channels play a central role in the control of secretory events.     

The enzymic potential of tissue kallikrein (rK1) in rat submandibular saliva depends on whether it was secreted via constitutive or regulated pathways

The enzymic activity and immunoreactivity of rat tissue kallikrein (rK1) secreted at rest by granular duct cells of unstimulated submandibular glands has been compared with that secreted on autonomic nerve stimulation. Although a direct vesicular, constitutive secretory pathway operates for rK1 secretion from granular duct cells of unstimulated and parasympathetically stimulated glands the rK1 was not present in a pro-form and actually showed a greater enzymic activity per unit immunoreactive protein than the granule-derived rK1 in sympathetically evoked saliva. Constitutively secreted rK1 was found to be in a single chain molecular form by reducing SDS gel electrophoresis. In contrast rK1 secreted from the storage granule pool of granular duct cells on sympathetic nerve stimulation was present in much higher amounts and occurred in both one-chain and two-chain forms as revealed by SDS gel electrophoresis under reducing conditions. The lower enzymic potential of rK1 in sympathetically evoked saliva might be accounted for by its conversion to a two-chain form.     

The localization of transforming growth factor alpha and epidermal growth factor receptor in stromal and epithelial compartments of developing human prostate and hyperplastic, dysplastic, and carcinomatous lesions

To gain insight into autocrine/paracrine mechanisms that may influence normal and abnormal growth of the human prostate, we studied the immunohistochemical localization of transforming growth factor alpha (TGF-alpha) and epidermal growth factor receptor (EGFr) in fetal, neonatal, prepubertal, and young adult glands. Results were compared with findings in specimens of benign prostatic hyperplasia (BPH), dysplasia (prostatic intraepithelial neoplasia--PIN), and carcinoma. EGFr was strongly and exclusively expressed in fetal basal cells, whereas TGF-alpha was localized in these and secretory cells as well as in differentiating smooth muscle cells. In neonatal and prepubertal glands, EGFr continued to be found only in basal cells, whereas TGF-alpha was now present in smooth muscle and infrequently in secretory cells. In the normal adult prostate, the receptor was strictly localized in basal cells and in the lateral plasma membranes of secretory cells, whereas its ligand was exclusively expressed in smooth muscle. This pattern persisted in PBH, but both EGFr and TGF-alpha staining appeared to be enhanced in their respective cellular compartments. Irrespective of grade, in dysplasia diffuse-moderate EGFr and strong TGF-alpha staining were both present in a majority of secretory cells. Similarly, most cells in Gleason grade 3 and 4 carcinomas expressed both EGFr and TGF-alpha. Our findings suggest that an unregulated paracrine mode of growth attends the development of BPH, whereas malignant transformation and progression involves autocrine/paracrine mechanisms reminiscent of those found in the developing prostate.     

Expression of gross cystic disease fluid protein-15/Prolactin-inducible protein in rat salivary glands

Gross cystic disease fluid protein-15 (GCDFP-15)/prolactin-inducible protein (PIP) is present at moderate levels in human submandibular and sublingual glands and is barely detectable in human parotid gland. The rodent homologue, PIP, has previously been identified in adult submandibular and lacrimal glands. Here we present the molecular characterization of rat PIP and show that this protein is a product of neonatal and adult rat submandibular, sublingual, and parotid glands. cDNA clones encoding rat PIP were isolated and sequenced. The deduced amino acid sequence of rat PIP shows 56% overall identity and 80% similarity with mouse PIP. By SDS-PAGE, secreted rat PIP has an apparent Mr of 17,000, with a minor proportion present as Mr 20-22,000 N-glycosylated forms. PIP was localized in rat salivary glands by immunogold silver staining. PIP was identified in acinar cells of developing and mature submandibular and parotid glands and at very low levels in sublingual gland serous demilunes. Typically, rat submandibular gland secretory proteins are produced by either acinar cell progenitors (Type III cells) or mature acinar cells. The expression pattern observed for PIP is similar to that previously reported for salivary peroxidase, an important component of nonimmune mucosal defense.     

Antigen retrieval in cryostat tissue sections and cultured cells by treatment with sodium dodecyl sulfate (SDS)

BACKGROUND: Steroid 5 alpha-reductase is essential for the intracellular accumulation of dihydrotestosterone (DHT), which mediates androgen effects on target tissue. METHODS: In the present study, we describe the differential expression and cellular localization of 5 alpha-reductase 1 and 2 isoenzymes in the human prostate, and untreated and hormone-resistant prostatic carcinomas. The secretory epithelium of normal and hyperplastic glands showed strong nuclear 5 alpha-reductase 1 reactivity. Accordingly, the DHT forming 5 alpha-reductase process in secretory luminal cell types may be mediated predominantly by the type 1 isoenzyme. The androgen-independent basal cell layer variably expressed type 1 and 2 isoenzymes in nuclear and cytoplasmatic compartments. This suggests that circulating androgens are involved to control the basal cell layer, which represents the proliferative compartment of the human prostate. RESULTS: When compared with benign prostate tissue, increased 5 alpha-reductase reactivity was detected in prostate cancer, particularly in high-grade tumors and androgen-insensitive states of the disease. In cancerous lesions, the type 1 isoenzyme tended to shift to the cytoplasm, while the nuclear staining remained unchanged or slightly increased. Referring to the type 2 isoenzyme, increased cytoplasmatic and nuclear enzyme activity was detected in malignant cells when compared with adjacent benign prostate tissue. Even endocrine differentiated tumor cells that consistently lacked the nuclear androgen receptor variably expressed 5 alpha-reductase immunoreactivity. CONCLUSIONS: Although the functional significance of the differential subcellular localization of type 1 and 2 isoenzymes is currently unknown, the present data suggest that prostate cancer retains the DHT forming 5 alpha-reductase process in high-grade lesions and recurrent disease. Accordingly, circulating androgens may be still significant in these hormone-refractory malignancies.     

Ultrastructural localization of microliths in salivary glands of cat

Although microliths occur in normal human salivary glands and may be an aetiological factor of sialadenitis, little is known of their natural history. In an attempt to remedy this, we investigated a large archival collection of normal and experimental feline parotid, submandibular and sublingual salivary glands. In submandibular and sublingual glands, microliths were detected ultrastructurally in: all types of acinar secretory cells; myoepithelial cells; ductal cells; lumina; intercellular spaces; basement membrane; stroma; macrophages; multinuclear giant cells; and neutrophils. Microliths were not detected ultrastructurally in parotid glands. Microliths appear to form in acinar cells during autophagy and in stagnant secretory material in lumina. Microliths appear to be removed by secretion in the saliva, discharge from cells laterally and basally, and engulfment by macrophages. There appears to be a turnover of microliths, which possibly is upset by secretory inactivity with a resulting accumulation that leads to localized obstruction and sialadenitis.     

Occurrence of somatostatin and insulin immunoreactivities in the stomach of sea bass (Dicentrarchus labrax L.): light and electron microscopic studies

Somatostatin (SST)- and insulin (INS)-immunoreactive (ir) cells were identified in the gut of sea bass (Dicentrarchus labrax) by immunofluorescence double staining and peroxidase-antiperoxidase (PAP) techniques for light microscopy and by immunogold method for electron microscopy using antisera to mammalian and fish peptides. SST-14 and SST-25 immunoreactivities coexisted in cells mainly located among the mucous neck cells of the gastric glands. Preabsorption controls showed that some SST-25- and, possibly, some SST-14-like peptides appeared in these cells. Immunoreactivity to fish INS, but not to mammalian INS (mINS) or insulin-like growth factor I (mIGF-I), was observed in all the SST-ir cells. The preabsorption controls suggest a cross-reaction of the fish INS antisera with SST-containing or type I cells. These cells displayed ovoid or round secretory granules with fibrous, medium electron-dense or homogeneous osmiophilic materials. Some gastric cells (type II) with round secretory granules of variable electron density, which were gold immunolabeled with bonito INS but not with mINS, mIGF-I, or SST antisera, were also found. INS-related peptide in type II cells of the sea bass stomach is suggested.     

The human external auditory canal, secretory system--an ultrastructural study

Human external auditory canal skin, with a special emphasis on the secretory system, was studied by light, transmission electron and scanning electron microscopy. Two types of secretory glands were observed: modified apocrine (ceruminous) and sebaceous. The sebaceous secretory cellere homogeneous; on the other hand, modified apocrine secretory cells contained heterogeneous secretory granules. They were ither dark granules or light granules. Evidence to support both the apocrine as well as the eccrine mode of secretion was noted in the modified apocrine gland. This finding is partly in agreement with early reports based on light microscopy with suggested only an apocrine mode and data based on transmission electron microscopy which showed only the eccrine mode. Significance of the secretion by the external ear canal and its role in a local immune defense system is discussed.     

Biosynthesis, processing, and targeting of sphingolipid activator protein (SAP )precursor in cultured human fibroblasts. Mannose 6-phosphate receptor-independent endocytosis of SAP precursor

Sphingolipid activator proteins (SAPs) are essential cofactors for the lysosomal degradation of glycosphingolipids with short oligosaccharide chains by acidic exohydrolases. SAP-A, -B, -C, and -D derive from proteolysis of a 73-kDa glycoprotein, the SAP precursor. In the present publication, we studied the intracellular transport and the endocytosis of SAP precursor in human skin fibroblasts. Our data indicate that SAP precursor bears phosphate residues on noncomplex carbohydrate chains linked to the SAP-C and the SAP-D domain and sulfate residues on complex carbohydrate chains located within the SAP-A, -C, and possibly the SAP-D domain. Treatment of fibroblasts with either bafilomycin A1 or 3-methyladenine indicates that proteolytic cleavage of SAP precursor begins as early as in the late endosomes. To determine whether targeting of SAP precursor depends on mannose 6-phosphate residues, we analyzed the processing of SAP precursor in I-cell disease fibroblasts. In these cells nearly normal amounts of newly synthesized SAP-C were found, although secretion of SAP precursor was enhanced 2-3-fold. Moreover, SAP-C could be localized to lysosomal structures by indirect immunofluorescence in normal and in I-cell disease fibroblasts. Mannose 6-phosphate was not found to interfere significantly with endocytosis of SAP precursor. Normal fibroblasts internalized SAP precursor secreted from I-cells nearly as efficiently as the protein secreted from normal cells. To our surprise, deglycosylated SAP precursor was taken up by mannose 6-phosphate receptor double knock out mouse fibroblasts more efficiently than the glycosylated protein. We propose that intracellular targeting of SAP precursor to lysosomes is only partially dependent on mannose 6-phosphate residues, whereas its endocytosis occurs in a carbohydrate-independent manner.     

Demonstration of anionic sites in human eccrine and apocrine sweat glands in post-embedded ultra-thin sections with cationic colloidal gold: effect of enzyme digestion on these anionic sites

We localized anionic sites ultrastructurally in human eccrine and apocrine sweat glands with a poly-L-lysine-gold complex (cationic colloidal gold). Anionic sites were labeled by incubating Lowicryl K4M-embedded sections on droplets of cationic colloidal gold. In eccrine sweat glands, colloidal gold particles were restricted to the basolateral membrane of the secretory cells at low pH, whereas the luminal membrane did not react with the gold particles. Chondroitinase ABC digested these anionic sites. This indicates that chondroitin sulfate and/or dermatan sulfate constitutes anionic sites in the basal labyrinth of eccrine sweat glands. In apocrine sweat glands, the luminal membrane of the secretory cells showed strong reaction at low pH, whereas the contraluminal membrane did not show any reaction. Neuraminidase completely digested these anionic sites, which indicated that the anionic charge of the apocrine lumen was due to sialic acid. Differences in distribution and susceptibility to enzymes of anionic sites in cell membranes between eccrine and apocrine sweat glands may reflect functional differences between these glands. Dark cell granules in eccrine secretory cells were negative for the anionic sites when sections were labeled without any pre-treatment. However, pre-incubation of the grids on EGTA or deionized water unmasked the anionic sites on the dark cell granules. The positive staining after EGTA treatment was greatly decreased by reincubation with CaCl2. These results suggested that Ca blocked anionic sites in dark cell granules. Exposed anionic sites were digested with chondroitinase ABC. This indicated that chondroitinase ABC and/or dermatan sulfate composed the anionic sites in dark cell granules.     

Fluoride stimulation of the rat parathyroid gland: an ultrastructural study

The parathyroid glands of rats given 150 ppm fluoride in the drinking water for 10 weeks are evaluated ultrastructurally and compared to the parathyroid glands of untreated rats. As a result of fluoride ingestion, the majority of the parathyroid cells are dark chief cells, indicating that these cells are in the active stages of the secretory cycle. More significantly, in the fluoride-treated rats, the cytoplasmic organelles of the dark chief cells are even more developed that those seen in the dark chief cells of untreated rats. The dark cells contain an electron-dense cytoplasm with abundant lamellar arrays of rough endoplasmic reticulum, spiral aggregations of free ribosomes, multiple dilated Golgi complexes, and increased numbers of secretory granules. The cells are at a minimum dimension with maximum tortuosity of the plasma membranes; and, as a result, large intercellular spaces are often seen between contiguous cells. Based on these observations, it is suggested that, in the fluoride-treated rat, a type of secondary hyperparathyroidism develops resulting in an increase in the organelles involved in protein synthesis and secretion.     

Histochemical study of magellanic penguin (Spheniscus magellanicus) minor salivary glands during postnatal growth

The histological and histochemical features of the minor salivary glands during postnatal development have been generally associated with the type of food ingested. However, recent studies support the fact that these salivary glands develop independently of the diet; in fact, minor salivary glands have similar morphological and histochemical characteristics in adult individuals of species with different diet regimens. Thus, the aim of this study was to characterize the developmental morphology of the penguin minor salivary glands and to contrast them with minor salivary glands of other species. The tongue, palatine, and mouth cavity (bottom) minor salivary glands of newborn, 1- to 20-day-old, and adult magellanic penguins were studied with hematoxylin-eosin, periodic acid-Schiff, alcian blue, toluidine blue, and lectin histochemistry. Minor salivary glands were present at all ages, although they were only moderately developed in animals less than 15 days old. After this age, glands were abundant in all age groups; in addition, cells from the glandular epithelium were functionally mature and secreted mucins. Nevertheless, in newborn to 15-day-old penguins, mucins were located only at the apical cytoplasm of mucous cells. In all ages, mucous cells displayed periodic acid-Schiff-positive, alcianophilic, and metachromatic reactions; among mucous cells, other orthochromatic cells appeared interspersed. From 15 days on, histochemical reactions became more intense until adulthood, and the cytoplasm of secretory cells was filled with glycoproteins and sulfomucins. Moreover, lectins bound to different oligosaccharides in mucous cells, depending on the stage of maturation of the glands. In conclusion, penguin minor salivary glands are already present at birth, and show progressive and quantitative increases in mucous secretion during postnatal development. These changes are necessary not only for nutrient ingestion, but also for nonimmune protection of the buccal cavity.     

Hatching glands in salmonid fishes, Salmo gairdneri, Salmo trutta, Salvelinus fontinalis and Salvelinus pluvius

The unicellular hatching glands (UHGs) of four species of salmonid fish, Salmo gairdneri, Salmo trutta, Salvelinus fontinalis and Salvelinus pluvius were studied by light and electron microscopy. The UHGs are distributed on the epidermis of head and yolk sac, and on the epithelium of the mouth and gills. Since these cells are large and include dilated cisternae of the endoplasmic reticulum from the primitive to the mature stages they are conspicuous. Around the Golgi complexes, there are consecutive figures showing synthesis of secretory granules with close relationships to the Golgi vesicles. The secretory granules grow in size and vary in density during maturation; some have enclosed cytoplasmic structures. At the hatching stage, they are discharged with some cytoplasmic structures from the UHG which is located in the superficial layer of epithelium. After exhaustion of the secretory granules, the remainder of the contents of UHGs is liberated.     

Effects of antimicrobial treatment at the end of lactation on milk yield, somatic cell count, and incidence of clinical mastitis during the subsequent lactation in a dairy herd with a low prevalence of contagious mastitis

Calcium-binding proteins (CaBPs) have been described as involved in the stimulus-secretion coupling mechanisms in secretory glands. CaBPs were revealed with 45Ca, after electrophoresis in SDS-PAGE and transference to Zeta probe membranes, in Duvernoy's or venom gland homogenates from three families of South American snakes: Viperidae (Bothrops jararaca and Crotalus durissus terrificus); Elapidae (Micrurus corallinus), and Colubridae (Phylodrias patagoniensis and Oxyrhopus trigeminus). A band with an estimated molecular weight of 12 KDa was found in all glands studied. Bands with 17, 28, and 67 KDa were found in all glands, except in O. trigeminus Duvernoy's gland. A 18 KDa band was found in Viperidae and Elapidae venom glands, and a 88 KDa band was observed only in Viperidae venom gland homogenates. Some of these CaBPs were identified by Western blotting or by immunohistochemistry, as parvalbumin (12 KDa) and calbindin (28 KDa). When the secretion of these glands were analyzed, CaBPs were detected only in B. jararaca venom, with bands of 14, 35, 42, and 72 KDa. The profile of CaBPs was not modified at different phases of the secretory cycle of the glands, as well as after isoproterenol treatment.     

Spatial organization of microtubules and microfilaments in larval and adult salivary glands of Drosophila melanogaster

We examined the distribution of microtubules and microfilaments by conventional fluorescence microscopy and laser scanning confocal microscopy in larval and adult salivary glands of Drosophila melanogaster. The cells of the larval salivary gland epithelium were characterized by the same spatial distribution of microfilaments, whereas microfilament localization was more complex in adult salivary glands, showing some regional differentiation. Microtubules distributed throughout the cell cytoplasm of the larval salivary glands, whereas in adult glands they were mostly observed in the basal or apical cytoplasm of the cells. These observations were related to the secretory process and the mechanism of saliva discharge.     

Localization by in situ hybridization of steroid 5alpha-reductase isozyme gene expression in the human prostate and preputial skin

PURPOSE: The synthesis of dihydrotestosterone is catalyzed by steroid 5alpha-reductase isozymes, designated as types 1 and 2. Controversial results have been reported on the identification of the cell types expressing each isozyme in the human prostate and genital skin. The objective of the present study was to clearly identify at the cellular level the cells containing each type of 5alpha-reductase isozyme. MATERIALS AND METHODS: We used for the first time an in situ hybridization technique involving use of [35S]-labeled oligonucleotide probes to determine the cell type expression patterns of the two 5alpha-reductase isozymes in human prostate and preputial skin. RESULTS: In the prostate, hybridization with types 1 and 2 5alpha-reductase antisense probes led to a positive reaction in both epithelial and stromal cells, while the sense probes did not generate any signal. The silver grain counts for both isozymes revealed a higher labeling in the epithelial cells. In fact, the ratio epithelial cells/stroma was around 2 for both 5alpha-reductase types 1 and 2. In the preputial skin, 5alpha-reductase type 1 was found to be highly expressed in all the layers of the epidermis with the exception of the stratum corneum while a lower labeling was observed in some fibroblasts as well as in the secretory cells of sebaceous glands and excretory duct cells of sweat glands. Type 2 5alpha-reductase showed a very similar pattern of distribution. CONCLUSION: It appears that, in two human tissues, the two 5alpha-reductase isozymes mRNAs are expressed by the same cell types. This new observation should help clarify the physiological role of each type of 5alpha-reductase isozyme.