Seasonal changes in the reproductive system of the female white-crowned sparrow,Zonotrichia leucophrys gambelii,in captivity and in the field

Summary The ventral apterium of free-living female White-crowned Sparrows (Zonotrichia leucophrys gambelii) becomes an incubation patch during the breeding season. At this time, it loses its feathers, increases in wet and defatted dry weight, and undergoes marked histological alterations. At times of year other than the breeding season, the apterium consists of a low squamous epidermis and a thin, poorly vascularized dermis of dense connective tissue. The dermis is separated from subcutaneous tissue by an internal elastic lamina. During the breeding season, the epidermis is a proliferative, stratified squamous eptihelium with well-defined basal, intermediate, transitional, and cornified layers; and the dermis consists of a superficial layer of collagen and a deep layer of highly vascular areolar connective tissue, noticeably edematous and mildly inflamed. Blood vessels are frequently in large groups in the center of the dermis. Edema and hypervascularity are most pronounced during incubation, but the epidermis is best developed during egg-laying. The apterium reverts to its basal state after the incubation period. Captive females, which do not breed, do not develop incubation patches.Estrogen is apparently responsible for feather loss and collagen synthesis. It and other unidentified hormones (probably prolactin and/or androgens) produce the hypervascularity, edema, and epidermal growth.This study was supported by an NIH Training Grant (GM 01276) from the National Institute of General Medical Sciences and by funds from the Faculty Research Council at Fordham University, New York, N.Y. It is a pleasure to acknowledge the assistance of Drs. Brina Kessel and George West at the University of Alaska during summer, 1968; Dr. William A. deGraw for help in the field; and Drs. Laura Englisch and James Wiggins, as well as my son, Robert, for help with the photomicrography. Wallace Moreland of the Singer-Friden Company kindly provided a desk calculator for my use. The content of this paper profitted substantially from the suggestions of Dr. Robert A. Lewis. This paper is based on part of a dissertation done to fulfill the Ph.D. requirements at Washington State University     

Structure of the skin of an air-breathing mudskipper, Periophthalmus magnuspinnatus

The epidermis of the mudskipper Periophthalmus magnuspinnatus consisted of three layers: the outermost layer, middle layer and stratum germinativum. Extensive vascular capillary networks were present near the superficial layer of epidermis and outermost layer. The diffusion distance between the vascular capillaries and the surface of epidermis was c . 1.5 ± 0.9μm. The middle layer consisted of small or voluminous cells swollen by epidermal cells. Due to the swollen cells, the thickness of the epidermis increased and the epidermis appeared web-like. The swollen cells contained tonofilaments, lucent contents and desmosomes. Fine blood capillaries were also discernible in this layer. Well-developed lymphatic spaces containing lymphocytes existed in the stratum germinativum. Numerous blood capillaries were present under the basement membrane. The dermis consisted of a stratum laxum and stratum compactum, and there was a definite area with acid mucopolysaccharides and a small scale in the stratum laxum. The skin had an epidermal pigment cell, dendritic melanophores (-cytes) containing melanin granules within their cytoplasm, and two kinds of dermal pigment cells, melanophores and colourless pigments containing reflecting platelets.     

Morphology and ultrastructure of possible integumentary sense organs in the estuarine crocodile (Crocodylus porosus)

The skins of crocodylids and gavialids can be distinguished from those of alligatorids by the presence of darkly pigmented pits, known as integumentary sense organs (ISOs), on the postcranial scales. The structure of ISOs, in Crocodylus porosus, was studied using light microscopy and scanning and transmission electron microscopy. The stratum corneum of the epidermis in the area of the ISO is thinner, while the stratum germinativum is thicker, relative to other regions of the integument. Beneath the epidermal layer the ISO region has a paucity of collagen fibers relative to the rest of the dermis. Widely dispersed fibrocytes, nerve terminals, and chromatophores occur throughout the ISO region of the dermis, but these elements are concentrated in the area immediately beneath the stratum germinativum in the ISO region. The morphology of the ISOs suggests that they are sensory organs. It has traditionally been assumed that sensory organs on the amniote integument have a mechanosensory function. However, alternate functional interpretations of this structure are possible, and a resolution awaits further work. © 1996 Wiley-Liss, Inc.     

Morphological Characteristics of the Dorsal Skin of Two Hynobiids and Their Adaptive Role in Aquatic and Terrestrial Habitats

The morphological characteristics of the dorsal skin of trunk in two species of hynobiid salamanders, Batrachuperus pinchonii and Hynobius chinensis were examined by light microscopy. The basic structures of the skin in the two species are similar and consist of two layers: epidermis and dermis. The epidermis consists of stratum corneum, stratum intermedium and stratum germinativum, while the dermis is composed of a stratum spongiosum and stratum compactum. However, some species-specific variation has been identified(e.g., the distribution of capillary vessels and gland cells, and the thickness of skin). H. chinensis is a terrestrial species and only lives in water during breeding period, but B. pinchonii is aquatic and remains aquatic throughout its lifetime. The differences in the distribution of capillary vessels and gland cells are related to their different habitats, and show a morphological adaptation.     

Changes in structure of ventral epidermis of Rana ridibunda during metamorphosis

Summary The organisation of the ventral epidermis organisation was followed throughout ontogenesis in Rana ridibunda. Epidermis of tadpoles with 2–3 limbs was organised into two layers: a stratum germinativum consisting of elongated columnar cells, and an outer stratum corneum consisting of two types of cuboid cells. Two types of cells can be distinguished; they are a light (clear) cell and a dark (dense) cell. In the 4-legged tadpoles the stratum corneum cells start to flatten and a replacement layer appeared underneath. A well-defined stratum germinativum is found and within it, epidermal glands. Moulting took place for the first time in tadpoles just before metamorphosis, and a well-organised stratum granulosum was formed still containing the two main types of epidermal glands. The flask cells appear in the juveniles for the first time, greatly increasing in numbers in the adult epidermis.     

Structure of the integument of a fresh-water teleost,Bagarius bagarius (Ham.) (Sisoridae,pisces)

The skin of Bagarius bagarius (Ham.) is devoid of scales but is rough due to the presence of numerous pentagonal epidermal elevations, which are separated by deep furrows at regular intervals. These elevated pentagonal regions of the epidermis are covered by dead cornified cells in the form of caps. As the old cap goes off a new one is formed by the death of the underlying epidermal cells. The middle layer of the epidermis is mainly composed of well defined polygonal cells. Their cytoplasm is granular in nature and give reactions for protein bound sulphydryl groups. The stratum germinativum is composed of two types of basal cells, the columnar cells and the spherical cells. The flask shaped mucous glands are restricted to the epidermal furrows and secrete either neutral or acidic mucopolysaccharides. Certain large specialysed granular cells are found in the epidermis which are grouped around the taste buds. These specialysed cells may be the photocytes. Two layers of the dermis can be distinguished—the relatively thin stratum laxum and the thick stratum compactum. Dermal papillae mainly support the taste buds. The pigment cells are arranged in two layers in the dermis. The subcutis is composed of loose connective tissues, richly infiltrated with the fat cells, nerves and blood capillaries.     

Localization of prolactin receptor in the dorsal and ventral skin of the frog (Rana ridibunda)

The dorsal and ventral skin in amphibians plays an important role in osmoregulation. Prolactin hormone is involved in regulation of amphibian skin functions, such as water and electrolyte balance. Therefore, amphibians may be useful as a model for determining the sites of the prolactin receptor. In this study, prolactin receptor was detected in frog dorsal and ventral skin using immunohistochemical staining method. Prolactin receptor immunoreactivity was localized in all epidermal layers except stratum corneum of dorsal skin epidermis, stratum germinativum layer of ventral skin epidermis, myoepithelial cells, secretory epithelium and secretory channel cells of granular glands in both skin regions. The mucous glands and secretory granules of granular glands did not show immunoreactivity for the prolactin receptor. According to our immunohistochemical results, the more widespread detection of prolactin receptor in dorsal skin epidermis indicates that prolactin is more effective in dorsal skin. Presence of prolactin receptors in epidermis points out its possible osmoregulatory effect. Moreover, detection of receptor immunoreactivity in various elements of poison glands in the dermis of both dorsal and ventral skin regions suggests that prolactin has a regulatory effect in gland functions.     

Structure and development of spines over the skin surface of the river puffer Takifugu obscurus (Tetraodontidae,Teleostei) during larval growth

The histological structure and development of spines on the skin surface of Takifugu obscurus were studied during larval development conducted artificially with an average 30‰ salinity and 18.0–20.3°C water temperature. The epidermis comprises an outermost layer, middle layer, and the stratum germinativum, and contains three types of gland cells: small spherical or flask‐shaped mucous cells, larger sacciform mucous cells, and large granular cells. The dermis and subcutis follow. The spines first appear over the ventral region at 10 days after hatching and consist of two parts: a central long tapering portion which projects into the epidermis and eventually outside of the body, and a short supporting basal portion that is embedded within the stratum compactum layer of the dermis. The central, long tapering portion has two very short processes on top until 25 days after hatching, but these two separate spines fuse into one 30 days after hatching. In contrast, the short supporting spines rooted at the base consist of three to six small spines (usually four to five spines) and are present even in the adult stage. Therefore, calcareous spines consisting of one central long spine and three to six smaller supporting spines form tetra‐ and septaradiate spines (mainly penta‐ and hexaradiate). The spines first appear over the ventral region.     

Use of retinoic acid for the analysis of dermal-epidermal interactions in the tarsometatarsal skin of the chick embryo

Feet of chicks are normally covered with scales. Injection of retinoic acid into the amniotic cavity of 10-day chick embryos causes the formation of feathers on the foot scales. To elucidate whether retinoic acid affects primarily the epidermis or the dermis, heterotypic dermal-epidermal recombinants of tarsometatarsal skin were tested as to their morphogenetic capacity, when grafted to the chick chorioallantoic membrane. Recombinants involving treated epidermis and untreated dermis formed feathered scales, while the reverse recombinants of untreated epidermis and treated dermis led to the formation of scales only. Likewise the association of treated tarsometatarsal dermis with untreated epidermis from a non-appendage-forming region (the midventral apterium) resulted in the formation of scales only. These results show that retinoic acid affects primarily the epidermis. Further insight into the mechanism of dermal-epidermal interaction was gained by heterotopic recombinations of early (8.5- and 10-day) untreated tarsometatarsal dermis with epidermis from the midventral apterium. These recombinants formed scales, proving that tarsometatarsal dermis is endowed with scale-forming properties as early as 8.5 days of incubation. Finally, it is concluded that retinoic acid acts on the chick foot epidermal cells by temporarily inhibiting their scale placode-forming properties, allowing their latent feather placode-forming properties to be expressed.     

Structure and Histochemistry of the Skin of a Torrent Catfish, Liobagrus mediadiposalis

The epidermis of the torrent catfish, Liobagrus mediadiposalis, consists of three layers: the outermost layer, middle layer and stratum germinativum. The epidermis consists of two types of skin glands, small mucus cell and voluminous club cell. The unicellular mucus cell contains acid sulfomucins (some sialomucins) and the club cell, sometimes binucleate, is proteinaceous. Well-developed vascularization is one of the characteristics of epidermis of L. mediadiposalis. Well-developed lymphatic spaces contain lymphocytes in the epidermis. The dermis lacks scales and consists mostly of a thick, dense connective tissue; its superficial region just below the basal membrane is supplied with fine blood capillaries. These histological features of the skin in L. mediadiposalis are consistent with that required for cutaneous respiration.     

Ventral vs. dorsal chick dermal progenitor specification

The dorsal and the ventral trunk integuments of the chick differ in their dermal cell lineage (originating from the somatic and somatopleural mesoderm respectively) and in the distribution of their feather fields. The dorsal macropattern has a large spinal pteryla surrounded by semi-apteria, whereas the ventral skin has a true medial apterium surrounded by the ventral pterylae. Comparison of the results of heterotopic transplantations of distal somatopleure in place of somatic mesoderm (Mauger 1972) or in place of proximal somatopleure (our data), leads to two conclusions. These are that the fate of the midventral apterium is not committed at day 2 of incubation and that the signals from the environment which specify the ventral and dorsal featherforming dermal progenitors are different. Effectively, Shh, but not Wnt -1 signalling can induce the formation of feather forming dermis from the embryonic somatopleure. Shh is not able, however, to trigger the formation of a feather forming dermis from the extra embryonic somatopleure. This brief report constitutes the first attempt, by comparing old and new preliminary results, to understand whether dermal progenitors at different sites are specified by different signalling pathways.     

Barnacle bonding: Morphology of attachment of Xenobalanus globicipitis to its host Tursiops truncatus

Xenobalanus globicipitis, a unique type of small pseudo‐stalked barnacle occurs on the appendages of cetaceans, including the common bottlenose dolphin Tursiops truncatus. In this study, we examined attachment structures of X. globicipitis and modifications to the skin of T. truncatus in areas of attachment compared to skin nearby an attachment site. Barnacles and their six calcareous footplates were measured for their length and width. There was a positive correlation of barnacle width and length to footplate width and length. The thickness of the stratum corneum increased significantly in areas of attachment compared to skin nearby a footplate. The mitotic stratum germinativum at the base of the dermal papillae did not change significantly in areas of attachment compared to skin nearby a footplate. The stratum germinativum lining the lateral walls of the dermal papillae was significantly thicker in areas of skin nearby a footplate compared to in areas of attachment. Skin of T. truncatus nearby a footplate, displayed dermal papillae extending from the dermis and pointing roughly perpendicular to the epidermal stratum corneum. At sites of X. globicipitis attachment, the dermal papillae were forced to extend laterally, parallel to the stratum corneum, and the dermal papillae length to width ratio at an attachment site was significantly higher than on skin near an attachment site. Our results show that attachment of X. globicipitis through production of footplates organized into calcareous rings, leads to a thickened stratum corneum of the epidermis, a thinner lateral mitotic stratum germinativum and displaced structures of the upper dermis. These resulting modifications to the epidermis and dermis of the host may add to securing barnacle attachment to its host. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.     

十一种无尾两栖类物种皮肤和肺显微结构

无尾两栖类动物的呼吸方式为肺呼吸和皮肤辅助呼吸,为探究两种呼吸器官的显微结构,本文采用解剖学和组织学的方法,对大蹼铃蟾(Bombina maxima)、腺角蟾(Megophrys glandulosa)、中华蟾蜍(Bufo gargarizans)、华西雨蛙(Hyla gongshanensis)、昭觉林蛙(Rana chaochiaoensis)、滇蛙(Dianrana pleuraden)、双团棘胸蛙(Gynandropaa yunnanensis)、贡山树蛙(Rhacophorus gongshanensis)、斑腿泛树蛙(Polypedates megacephalus)、饰纹姬蛙(Microhyla fissipes)、多疣狭口蛙(Kaloula verrucosa)的皮肤和肺的形态及显微结构进行观察。结果显示,背部和腹部皮下可见血管交错成网状,皮肤由表皮层和真皮层构成。除华西雨蛙外,其余10种均有分布于真皮疏松层与致密层间的钙化层;色素细胞位于疏松层上层,体背色素层较发达。肺囊状,中空密布血管,分为大小相当的左右肺叶,两肺叶相通并与心粘连,无气管和支气管。肺由肺囊壁、隔膜、毛细血管、肺泡细胞等结构组成。肺囊壁分为胸膜层、中间层和内层:胸膜层由扁平细胞构成,中间层由结缔组织构成,内层由肺细胞和毛细血管组成,隔膜由毛细血管和结缔组织构成,游离隔膜向中部靠拢可形成半封闭腔室,结合隔膜与肺囊壁形成封闭小腔室。在这11个物种中,肺较发达的个体,其皮肤结构中黏液腺的数量就会相对较少,组织形态学特征表现出与环境适应性关系较大,而受到系统发育关系影响较小。     

The permeability barrier in the epidermis of the grass snake during the resting stage of the sloughing cycle

Summary Tracer and freeze-fracture replication techniques show that there are two morphologically and topographically distinct permeability barriers in the epidermis of the grass snake. Tight junctions interconnect the apico-lateral plasma membranes of the uppermost living cells, establishing an ionic or osmotic gradient between the stratum germinativum and alpha layer. The second barrier is formed by intercellular lipid sheets in the overlying mesos layer, which are very similar to the barrier found in the stratum corneum of mammals.     

Fibronectin (FN) localizations in mitochondria-rich cells of frog epidermis

Indirect immunoperoxidase detection of fibronectin (FN) in the ventral frog epidermis showed that only one type of epidermal cell, the mitochondria-rich cells (MRC), was FN-detected. FN was found in MRC having rounded, flask-like and intermediate shapes, located at different levels of the epidermis between the stratum germinativum and the stratum corneum. These cells contained cytoplasmic FN particularly in the form of small granules. Our results support the view that MRC differ from other epidermal cells in their in vivo FN localizations.     

A comparative study on vascularization and the structure of the epidermis of an amphibious mudskipper fish,Scartelaos gigas (Gobiidae,Teleostei), on different parts of the body and the appendages

Epidermal structure of the amphibious mudskipper, Scartelaos gigas (Gobiidae), was investigated in relation to their terrestrial adaptation whereby a histological study on the epidermis of 15 regions including nine body regions, five fins and the sucking disc was carried out. The structure of the epidermis consists of three layers: an outermost layer with polygonal cells or rather flattened cells, small cells and mucous cells; a thick middle layer with voluminous cells swollen by epidermal cells; and the stratum germinativum. A dermal bulge was located at each apical area of the epidermis of almost all body regions, but was not existent in the operculum and the appendages, including none of the fins or the sucking disc. In the epidermis of the body regions, the dermal bulges had numerous dermal capillaries just beneath the stratum germinativum. By contrast, the appendages never had dermal capillaries due to the absence of the dermal bulge. Based on these results, the cutaneous air uptake in S. gigas would seem to be more effective in the upper body regions that are most often exposed to air than in the lower body regions, however, cutaneous air uptake is not likely to occur in the appendages.     

Characterization of metamorphic changes in anuran larval epidermis using lectins as probes

The skin of an adult frog of Xenopus laevis was characterized by the reactivity of 20 lectins. The lectins were classified into six groups in their binding to the epidermal cells: Lycopersicon esculentum lectin (LEL)-type which was positive for all epidermal cells; Pisum sativum agglutinin (PSA)-type for stratum germinativum; succinylated wheat germ agglutinin (sWGA)-type for strata spinosum, granulosum and corneum; Dolichos biflorus agglutinin (DBA)-type for strata germinativum and spinosum; peanut agglutinin (PNA)-type for stratum spinosum; and Ulex europaeus agglutinin (UEA-I)-type for strata granulosum and corneum. PSA and sWGA were utilized as markers of mitotically active germinative cells and the differentiated cells of the epidermis, respectively, to describe the metamorphic conversion of larval epidermal cells to adult type. PSA stained all epidermal cells of tadpoles before metamorphic climax. At the end of metamorphosis, PSA-positive cells were restricted to cells in the basal layer of body epidermis while all the tail epidermis remained PSA-positive. The other cell marker, sWGA, only stained apical cells in tadpole epidermis. During the metamorphic climax, sWGA-positive cells appeared in the cells beneath the stratum corneum of the body region, but not in the tail region. The present study demonstrates that PSA and sWGA are useful to investigate metamorphic changes in tadpole epidermal cells.     

Morphological,immunohistochemical and ultrastructural characterization of the skin of turbot (Psetta maxima L.)

This study was undertaken to identify the normal morphologic, immunohistochemical and ultrastructural features of skin of the turbot (Psetta maxima L.). In the turbot skin, three morphologically distinct layers were identified: epidermis, dermis and hypodermis. The epidermis was non-keratinizing, stratified squamous epithelium that varies in thickness from 5 to 14 cells and 60 to 100 μm in size. Goblet cells were seen randomly distributed between malpighian cells in the epidermal layer. These mucous cells were mainly located in the upper third of the epidermis and displayed a spherical to elongated morphology. Dermis was divided in two well-differentiated layers, the superficial stratum laxum and the deeper stratum compactum. Hypodermis was a loose layer mainly composed by adipocytes but we could observe variable amounts of fibroblast, collagen and blood vessels. In turbot two pigmentary layers could be identified: the pigmentary layer of dermis was located between basement membrane and dermis and the pigmentary layer of hypodermis immediately above the muscular layer. Three different types of chromatophores were present: melanophores, iridophores and xanthophores. The main differences observed between groups of fish with different colouration were in the amount of melanophores and xanthophores. The purpose of this article is to provide an overview of normal cutaneous biology prior to consideration of specific cutaneous alterations and diseases in turbot.     

Light and scanning microscopic studies of integument differentiation in the grass snake Natrix natrix L. (Lepidosauria,Serpentes) during embryogenesis

We analysed the differentiation of body cover in the grass snake (Natrix natrix L.) over the full length of the embryo's body at each developmental stage. Based on investigations using both light and scanning electron microscopes, we divided the embryonic development of the grass snake integument into four phases. The shape of the epidermal cells changes first on the caudal and ventral parts of the embryo, then gradually towards the rostral and dorsal areas. In stage V on the ventral side of the embryo the gastrosteges are formed from single primordia, but on the dorsal side the epidermis forms the scale primordia in stage VII. This indicates that scalation begins on the ventral body surface, and spreads dorsally. The appearance of melanocytes between the cells of the stratum germinativum in stage VII coincides with changes in embryo colouration. The first dermal melanocytes were detected in stage XI so in this stage the definitive skin pattern is formed. In the same stage the epidermis forms the first embryonic shedding complex and the periderm layer begins to detach in small, individual flakes. This process coincides with rapid growth of the embryos.     

似鲇高原鳅皮肤与鳍的组织学观察

采用石蜡切片技术及H.E和AB-PAS染色方法,对似鲇高原鳅(Triplophysa siluroides)头部、腹部、背部、侧线部和尾部皮肤结构及胸鳍、腹鳍、背鳍、臀鳍和尾鳍的组织结构进行观察。各部位皮肤均由表皮和真皮构成,真皮包括疏松层和致密层,不同部位皮肤厚度不同。表皮层腹部最厚,为(84.62±10.82)μm,侧线部最薄,为(14.97±3.95)μm,各部位表皮厚度差异显著。表皮层分布着黏液细胞、棒状细胞及味蕾。疏松层头部最厚,为(282.71±70.56)μm,尾部最薄,为(29.07±4.88)μm,该层分布有黑色素细胞、空泡状细胞和颗粒腺,而黏液腺分布于致密层。各部位的鳍均由表皮层、胶原纤维层、胶原下层及鳍条构成,表皮层与皮肤表皮层组成相似,鳍条是矿化的结缔组织。