摘要:

AbstractMembrane events during apocrine and merocrine secretion of rat ventral prostate epithelial cells were analyzed by freeze‐fracture. Early morpho‐logical manifestation of both secretory modes involves focal clearance of microvilli characterized by their progressive inclination and attenuation over the apical membrane. Merocrine secretion includes invasion of the apical microfilament web by the secretory vesicle and clearance of membrane particles at the site of its interaction with the apical plasmalemma. During apocrine secretion, a portion of the plasma membrane cleared of microvilli projects into the lumen. Growth of this projection is accompanied by a progressive, but partial, clearing of membrane particles and results in the formation of a large bleb containing dilated endoplasmic reticulum cisternae. Completion of the process involves “degeneration” of the bleb and its release by constriction of a neck and, possibly, fusion of vesicular or tubular structures. Swelling and blebbing of microvilli are shown to be preparation ar

ISSN:0003-276X    

DOI:10.1002/ar.1091980402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractCat intrafusal muscle fibers were examined histochemically in serial transverse sections of tenuissimus muscle spindles. The “myofibrillar” adenosine triphosphatase staining reaction was used to recognize the nuclear bag and the nuclear chain fibers in 309 spindle poles. Poles of 40 nuclear chain fibers extended for 1,000 μm or more beyond the termination of the spindle capsule. These long chain fibers stained less intensely for nicotinamide adenine dinucleotide tetrazolium reductase (NADH‐TR) than the typical chain fibers of shorter polar length. In sections stained for cholinesterases (ChE), the extracapsular regions of most long chain fibers displayed one or two short, dense “plate”‐type ChE deposits, which may represent the terminals of skeleto‐fusimotor axons. In addition, about one‐third of the long chain fibers displayed one or more thinner and smaller areas of ChE activity, possibly corresponding to the endings of fusimotor axons. The overall ChE staining pattern of the typical chain fibers was unlike that of the long chains. However, some of the shorter nuclear chain fibers resembled long chain fibers with the NADH‐TR reaction, even though their ChE “plates” were located intracapsularly.It is concluded that nuclear chain fibers in the cat spindle form a class of intrafusal fibers with heterogeneous histochemical properties, and that the long chain fibers repre

ISSN:0003-276X    

DOI:10.1002/ar.1091980403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractScanning electron microscopy (SEM) was used to study the arrangement of elastic fibers in the canine saphenous vein as the basis for further studies of veins used in by‐pass grafting operations. The elastic fiber arrangement in distended and non‐distended veins was examined in both immersion‐fixed and perfusion‐fixed vessels. Transmission electron microscope (TEM) observation of the SEM samples confirmed the identity of these fibrillar structures as elastic fibers. In addition, specific stains for elastic fibers (Verhoeff's iron hematoxylin and orcein) were used. The elastic fibers forming the internal elastic lamina were arranged in a fishnet‐like pattern. Large‐diameter fibers, running longitudinally along the vascular wall, were interconnected by smaller oblique fibers. Together the fibers formed an elastic cylindrical network between the endothelium and the smooth muscle cells. The thicker longitudinal fibers were the same diameter in distended and non‐distended veins. By contrast, the oblique fibers were thinner and more complexly branched in distended veins. The architecture of the elastic fiber network contributes to vascular flexibility and allows circumferential distension. The interconnecting oblique fibers presumably serve to distribute internal pressure equally around th

ISSN:0003-276X    

DOI:10.1002/ar.1091980404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractA fine structural study has confirmed earlier light microscopic observations indicating that prolactin cells are the only endocrine cells present in the main body of the rostral pars distalis of the adenohypophysis ofFundulus heteroclitus, a killifish common in New England coastal waters. Some ACTH cells occurred in thin plaques applied to the neurohypophysial trunk in the posterior part of the region. In freshwater‐adapted specimens the volume occupied by the prolactin cell mass was larger than in saltwater‐adapted specimens and contained larger prolactin cells. A paucity of contact specializations between the parenchymal cells may facilitate their spatial rearrangement as the prolactin cell population varies with changes in ambient salinity. Many fine neurohypophysial processes penetrated deeply into the rostral pars distalis and contained Type B (aminergic) nerve fibers believed to modulate prolactin secretion. These fibers ended mainly on the basement membrane that separates the neurohypophysial processes from the parenchyma. Synaptic contacts on prolactin cells were not observed but no prolactin cell appeared to be more than five cell widths from such a nerve terminal. The results emphasize the usefulness of the rostral pars distalis of this easily obtained and maintained teleost for studies of prolactin cell funct

ISSN:0003-276X    

DOI:10.1002/ar.1091980405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe effects of ethidium bromide (EB) on rat adrenocortical cells were investigated by biochemical and stereological methods. It was found that a treatment with ip. injections of 10 μg/gm of EB every 12 hours induced a persistent inhibition of the incorporation of3H‐thymidine and3H‐uridine into the mitochondrial fraction, but not into the nuclear fraction. Chronic treatment with this dose of EB provoked in zona fasciculata cells of rats treated with maintenance doses of ACTH a noticeable decrease in the volume of the mitochondrial compartment (due to the decrease both in the number per cell and in the average volume of the organelles) and in the surface area of the mitochondrial cristae. These findings lend support to the hypothesis that the mechanism underlying the ACTH‐induced maintenance of the growth of adrenocortical mitochondria involves mitochondrial DNA reduplication and transcr

ISSN:0003-276X    

DOI:10.1002/ar.1091980406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe distribution of the glycoprotein, fibronectin, within the cranial region of stage 8–16 chick embryos was examined by indirect immunofluorescence using paraffin sections exposed to affinity‐purified rabbit anti‐human CIG and FITC‐conjugated goat anti‐rabbit immunoglobulins. Fluorescence was present within the matrix surrounding the cranial mesenchyme, along the basal surfaces of all epithelia, and surrounding the notochord at all stages. Fluorescence associated with the floor of the foregut was particularly intense. The fluorescent layers beneath the ectoderm and endoderm of the oral (oropharyngeal) membrane at stage 8 merged into a single, continuous, intensely fluorescent line as the extra‐cellular space within the oral membrane narrowed during stages 9–12. This line of uniform fluorescence parallels the previously described histological reorganization of the extracellular compartment of the oral membrane, but the ultrastructural localization of this fluorescent material remains unknown. Fluorescence was also intense beneath the foregut endoderm in the presumptive cardiac region caudal to the oral membrane and was continuous with strands of fluorescent material extending into the matrix of the dorsal mesocardium and cardiac jelly of the developing tubular heart. These observations indicate that the extracellular matrix associated with the floor of the entire foregut contains fibronectin during stages encompassing the formation and rupture of the oral membrane. The presence of fibronectin within the oral membrane and dorsal mesocardium, as well as between Rathke's pouch and infundibulum and within the closing plates between ectodermal clefts and endodermal pouches, is consistent with the possibility that this glycoprotein may play a role in adhesion a

ISSN:0003-276X    

DOI:10.1002/ar.1091980407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe critical time of onset of the reciprocal relationship between the pituitary and the thyroid in fetal rats was assessed by the appearance of goiters in fetuses after maternal treatment with goitrogen, propylthiouracil (PTU), on various days of gestation. The assessment was based on changes in the weight and histology of the fetal thyroids. The day following overnight mating was regarded as day 1 of gestation. Pregnant rats were treated with 40 mg PTU each day for two days and autopsied on the third day. The various experimental periods were days 16–18, 17–19, 18–20, 19–21, and 20–22. PTU given to pregnant rats on days 16 and 17 did not cause any change in the fetal thyroids. PTU given on days 17 and 18 caused only a slight increase of fetal “thyroid weight/body weight” ratio. In all other experimental periods (days 18–20, 19–21, and 20–22), PTU induced conspicuous goiters in fetuses, which was reflected by an increased weight of thyroids, an increased height of follicular cells, and a decreased amount of colloid stored in follicles. The results suggest that in fetal rats, the reciprocal relationship between the pituitary and the thyroid is established on approximately days

ISSN:0003-276X    

DOI:10.1002/ar.1091980408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractBlocks of osmium‐fixed human digital skin, representing a total area of 5 sq mm, were cut serially parallel to the skin surface starting with the epidermis for electron microscopical studies. At intervals, single 1‐μ sections were taken and used for recording the microtopography of the receptor organs at various levels. Graphic reconstructions of 28 nerve endings were made.It was found that the digital skin accommodated up to 80 dermal papillae and three to four sweat duct orifices per square millimeter. Each papilla contained one to three fenestrated capillary loops. More than 60% of all papillae contained free nerve endings, sometimes up to five in a single papilla. As a result, up to 100 free nerve endings were counted per square millimeter. Intraepidermal endings were also present, one to five per square millimter. No endings of any kind were found within the boundary zones between the papillary ridges and in the immediate vicinity of the sweat ducts.The origin of a free ending was marked by the perikaryon of a modified Schwann cell, which constituted the terminal cell of the Schwann sheath. The perikaryon was situated at the base of the dermal papilla, while its distal process provided the cytoplasmic sheath to the axon terminals and their branches. Sometimes two endings merged into a single receptor organ. The terminal Schwann cell frequently served as a rallying point of endings. Three morphological kinds of free endings were observed: open endings, beaded endings, and plain endings. The intraepidermal endings were the derivatives of the plain endings.The free endings in the digital skin had essentially vertical distribution. Each ending covered a minute surface area of skin in a punctate pattern. This is in contrast to the mode of distribution of the free (penicillate) endings of the human hairy skin. Each penicillus covers a large horizontal skin area and overlap̀s that of their neig

ISSN:0003-276X    

DOI:10.1002/ar.1091980409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe skin of primate eyelid contains three distinctive sensory nerve terminals. Small down hairs have a collar of lanceolate terminals that are formed by ramifications of the six to eight myelinated afferent fibers. Extensions of Schwann‐cell cytoplasm form masses of cytoplasmic lamellae associated with these terminals. Every large hair or eyelash contains a large pilo‐Ruffini as well as sparse lanceolate terminals. The eyelash Ruffini corpuscle resembles those of monkey facial guard hairs, sinus hairs, and joint capsules of the cat and pigeon. Sparse lanceolate terminals present between the Ruffini corpuscle and eyelash external root sheath resemble those of vellus hairs. On rare occasion Merkel cells are present in the hair follicle external root sheath above the sebaceous gland. Merkel touch spots, orTastscheiben, are located between contiguous eyelashes as small rete pegs containing several Merkel cell‐neurite complexes innervated by one or two myelinated afferent fibers. The function of this array of sensory terminals is presumed to represent an extensive mechanism of protection for the cornea and globe. On the basis of studies reported to date we can conclude that the Ruffini corpuscles (and related receptors) are the ubiquitous mechanoreceptors of cutaneous and musculoskeletal systems in birds as well as ma

ISSN:0003-276X    

DOI:10.1002/ar.1091980410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractLamprey,Entosphenus japonicus, cerebral blood vessel autonomic nerve supply was studied with fluorescence and cholinesterase histochemistry and electron microscopy.Nerve fibers emitting a yellow fluorescence characteristic of serotonin (Exc./Em. max.; 380/530 nm) were found on the major cerebral and pial arteries, but not acetylcholinesterase (AChE)‐positive ones. Single ganglion cells also emitting a strong yellow fluorescence were seen in the artery adventitia. On rare occasions these cells were observed in pairs. Terminal varicosities of central catecholamine‐containing nerves (Exc./Em. max.; 410/475 nm) were observed on parenchymal capillaries, but not central AChE‐positive nerve terminals.In ganglion cells, dense cored vesicles (ca. 130 nm in average diameter; DCV) were abundant in the Golgi area, suggesting their formation at this site. Two types of DCV were observed; one with a homogeneous dense core and the other with a granular core. DCV were numerous in axons as well, axons in which many small clear vesicles (40–60 nm in diameter) as well as DCV were occasionally observed. The question of whether the small clear vesicles or the DCV contained serotonin could not be r

ISSN:0003-276X    

DOI:10.1002/ar.1091980411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY