Fifteen adult Soay rams were employed in this study to investigate the effect of melatonin on the
scrotal skin using histological, histochemical, and morphometrical analysis. The results revealed
that the melatonin treated group showed a significant increase in the thickness of the epidermis, the
cross-sectional area of blood capillaries and nerve fibers compared with the control one. In addition,
obvious hypertrophy and hyperplasia were detected in the sebaceous glands in association with a
significant increase in the number and diameter of apocrine sweat glands with well-developed secretory
activity. S100 protein and cytokeratin-19 strongly stained the basal cells of sebaceous glands in the
melatonin treated group incomparable to the control group. Moreover, the nerve fibers were intensively
immunoreacted for S100 and cytokeratin proteins in the melatonin treated group in contrast to the
control one. A high number of telocytes (TCs) could be identified in the treated group around the
nerve fibers and blood vessels in the dermis. The number of Langerhans cells showed a significant
increase in the melatonin groups that were identified by MHC II and PGP 9.5 within the epidermal layer.
Furthermore, a significant increase in the number of dendritic cells was identified in the melatonin
group, which were distributed within the dermis, around hair follicles, sebaceous glands, and sweat
glands and were strongly expressed PGP-9.5, MHC-II, VAMP, SNAP, keratin-5, and cytokeratin-19
immunoreactivity. Notably, Merkel cells showed a significant increase in the number in the melatonin
group that could be stained against nestin, SNAP, and VAMP. On the other hand, the secretory
granules in sweat glands were exhibited a strong positive reactivity for synaptophysin in melatonin
group. The current study showed that the administration of melatonin induced a stimulatory effect on
keratinocytes, non-keratinocytes, sebaceous and sweat glands, hair follicles, as well as the vascular,
neuronal, and cellular constituents of the dermis.

This study investigated the histomorphological features of developing rabbit respiratory acini during the postnatal period. On the 1st day
of postnatal life, the epithelium of terminal bronchiole consisted of clear cells which intercalated between few ciliated and abundant nonciliated
(Clara) cells. At this age, the rabbit lung was in the alveolar stage. The terminal bronchioles branched into several alveolar ducts,
which opened into atria that communicated to alveolar sacs. All primary and secondary inter-alveolar septa were thick and showed a doublecapillary
network (immature septa). The primitive alveoli were lined largely by type-I pneumocytes and mature type-II pneumocytes. The type-
I pneumocytes displayed an intimate contact with the endothelial cells of the blood capillaries forming the blood–air barrier (0.90 ± 0.03 μm in
thickness). On the 3rd day, we observed intense septation and massive formation of new secondary septa giving the alveolar sac a crenate
appearance. The mean thickness of the air–blood barrier decreased to reach 0.78 ± 0.14 μm. On the 7th day, the terminal bronchiole epithelium
consisted of ciliated and non-ciliated cells. The non-ciliated cells could be identified as Clara cells and serous cells. New secondary septa were
formed, meanwhile the inter-alveolar septa become much thinner and the air–blood barrier thickness was 0.66 ± 0.03 μm. On the 14th day, the
terminal bronchiole expanded markedly and the pulmonary alveoli were thin-walled. Inter-alveolar septa become much thinner and single
capillary layers were observed. In the 1st month, the secondary septa increased in length forming mature cup-shaped alveoli. In the 2nd
month, the lung tissue grew massively to involve the terminal respiratory unit. In the 3rd month, the pulmonary parenchyma appeared morphologically
mature. All inter-alveolar septa showed a single-capillary layer, and primordia of new septa were also observed. The thickness of
the air–blood barrier was much thinner; 0.56 ± 0.16 μm. TUNEL assay after birth revealed that the apoptotic cells were abundant and distributed
in the epithelium lining of the pulmonary alveoli and the interstitium of the thick interalveolar septa. On the 7th day, and onward, the
incidence of apoptotic cells decreased markedly. This study concluded that the lung development included two phases: the first phase (from
birth to the 14th days) corresponds to the period of bulk alveolarization and microvascular maturation. The second phase (from the 14th days
to the full maturity) corresponds to the lung growth and late alveolarization.

The present study aims to investigate the histological, histochemical and electron microscopic changes
of the caecal proximal part of Japanese quail during both pre- and post-hatching periods starting from
the 2nd embryonic day (ED) until four weeks post-hatching. On the 2nd and 3rd ED, the primordia of caeca
appeared as bilateral swelling on the wall of the hindgut. On the 7th ED, the lamina propria/submucosa
contained the primordia of glands. On the 8th ED, rodlet cells could be observed amongst the epithelial
cells. On the 9th ED, the caeca began to divide into three parts with more developed layers. With age,
the height and number of villi increased. On the 13th ED, immature microfold cells (M-cells) could be
identified between the surface epithelium of the villi. The caecal tonsils (CTs) appeared in the form of
aggregations of lymphocytes, macrophages, dendritic cells and different types of leukocytes. Telocytes
and crypts of Lieberkuhn were observed at this age. On hatching day, the crypts of Lieberkuhn were
well-defined and formed of low columnar epithelium, goblet cells, and enteroendocrine cells. Posthatching,
the lumen was filled with villi that exhibited two forms: (1) tongue-shaped villi with tonsils
and (2) finger-shaped ones without tonsils. The villi lining epithelium contained simple columnar
cells with microvilli that were dispersed with many goblet cells, in addition to the presence of a high
number of intra-epithelial lymphocytes and basophils. Moreover, the submucosa was infiltrated by
numerous immune cells. CD3 immunomarker was expressed in intraepithelial lymphocytes, while CD20
immunomarker showed focal positivity in CTs. In conclusion, the caecal immune structures of quails at
post-hatching were more developed than those in pre-hatching life. The high frequency of immune cells
suggests that this proximal part may be a site for immunological surveillance in the quail caecum. The
cellular organisation of the caecum and its relation to the immunity was discussed.

The current investigation was carried out to record the final stages of the development of both middle and distal parts of quail ceca,
Coturnix coturnix japonica to understand the role of ceca in digestion, immune system, and absorption. The cellular and subcellular structures,
including epithelial cell height, microvillus surface area, the proportion of goblet cells, the thickness of muscle layer, and cecum diameter
showed great variations during the development. An undeveloped smooth muscularis mucosa was observed for the first time on the
ED5. Primordia of glands were observed on the ED7. On the ED15, the middle part exhibited two shapes of mucosal villi: tongue-shaped
villi and U-shaped. The plicae and crypts of Lieberkühn were demonstrated on the hatching day. The lymphatic tissues appeared in the wall
of both parts of the ceca at the 4 weeks of age. Scanning electron microscopy revealed a great difference in the mucosal surface between
different regions. Telocytes were observed in-between the muscle fibers and formed a network during the post-hatching period. Because
of fermentation and other bacterial or chemical processes that have been shown to occur in the ceca, this study supports two hypotheses:
the cecal development is related to diet and the cecal epithelium act as a site for primary absorption of nutrients or for re-absorption of
electrolytes or amino acids derived from the urine.

Many studies have been carried out to investigate the histological structure of the trachea in many species of birds. However, the
cellular organization of the trachea in the mallard duck is still unclear. This study was performed on 12 sexually mature maleMallard
duck to demonstrate the cellular organization of the trachea using light and electronmicroscopy. The tracheal epithelium is considered
the first line of defense against airborne pathogens. The mallard trachea was lined by a pseudostratified ciliated columnar epithelium
that contained many morphologically distinct cell types: ciliated, non-ciliated, basal cells that encircled by a population of subepithelial
immune cells, fibroblasts, and telocytes (TCs). Telocytes were first recorded in duck trachea in this study and showed a
wide variety of staining affinity. They presented two long telopodes that made up frequent close contacts with epithelium, tracheal
cartilages, and other neighboring TCs, immune cells, blood capillaries, and nerve fibers. TCs express VEGF and S-100 protein. The
immune cells include mast cells, eosinophils, basophils, lymphocytes, plasma cells, and dendritic reticular cells. The ciliated tracheal
epithelium was interrupted by numerous intraepithelialmucous glands and solitary goblet cells. Thismucociliary apparatus constitutes
the major defense mechanism against inhaled foreign materials. The cellular organization of the duck trachea and its relation to the
immunity was discussed.

The immune system of fish consists of two
main components, innate and adaptive immunities.
Innate immunity is non-specific and acts as the primary
line of protection against pathogen invasion, while
adaptive immunity is more specific to a certain
pathogen/following adaptation. The adaptive immune
system consists of the humoral and cellular components.
Cytotoxic T-lymphocyte cells are the major component
of the cellular immunity that frequently kills viral-,
bacterial- or parasitic-infected cells. According to the
anatomical location, the mucosal-associated lymphoid
tissue (MALT) in teleost fish subdivides into gutassociated
lymphoid tissue (GALT), gill-associated
lymphoid tissue (GIALT), and skin-associated lymphoid
tissue (SALT). The MALTs contain various leukocytes;
including, but not limited to, lymphocytes (T and B
cells), plasma cells, macrophages, and granulocytes.
Macrophages are multifunctional cells that are mainly
involved in the immune response, including;
phagocytosis and degradation of foreign antigens, tissue
remodeling, and production of cytokines, chemokines
and growth factors. An interesting feature of teleost
macrophages is their ability to form melanomacrophage
centers (MMC) in the hemopoietic tissues. Dendritic
cells, rodlet cells, mast cells, eosinophilic granular cells
(ECGs), telocytes, osteoclasts, club cells, as well as,
barrier cells have been recorded in many fish species and
have many immunological roles. This paper aims to
summarize the current knowledge of the immune cells
present in fish tissues serving as anatomical and
physiological barriers against external hazards. Increased
knowledge of fish immune systems will facilitate the
development of novel vaccination strategies in fish.

This book will provide the readers with the most contemporary and
useful text possible. The book describes the most important recent developments
in sciences of fish histology. I am also recognizing that the readers
are faced with the tasks of learning an ever-increasing number of facts in
an ever-decreasing period of time. Because of this, every attempt has been
made to shorten the text wherever possible and to organize information in
a way that will facilitate learning.
Fish constitute nearly 60% of all vertebrate species and are economically
of major importance. The reporting of normal histology of fish
tissues and organs serves as a foundation upon which to gather and build
our ichthyopathology knowledge base.
The aim has been to present a general reference guide providing an
extensive set of histological images of fishes. Although several studies
treat histological aspects in relation to pathology, no recent synthesis on
the normal histology of fish is available. Therefore, I believe that this
textbook will be a main contribution to this field. The book is designed
to provide students with a foundation in understanding and interpreting
histologic and cytologic preparations and normal tissue components.
A text and colored atlas of histology of fish is designed for use by
students and researchers, biologists, ichthyologists, fish farmers, veterinarians
working in fisheries and, of course, by comparative histologists
who want to learn more about the fish world. As a further aid to learning,
numerous photomicrographs and electron micrographs amplify the text
in addition to particular emphasis on diagrams and tables to summarize
morphologic and functional features of cells, tissues, and organs.
All photomicrographs are original. Light microscopy has been illustrated
with color photomicrographs. Tissue and organ samples chosen to
illustrate this work have been selected from reared food fish, as well as
from species in the aquarium and in the wild.
 

This study was carried out to analyze the architecture of the skin of the upper lip
region in silver carp fishes using light, scanning, and transmission electron microscopies.
The skin was composed of epidermis, dermis, and hypodermis. The epidermis of the
upper lip was characterized by the presence of large number of metachromatic mucous
goblet cells, which showed positive reaction with Periodic Acid–Schiff (PAS), Alcian
blue (AB), and toluidine blue. The electroreceptive lateral line system was organized
into ampullary and tuberous organs. The scanning electron microscopy showed that
the surface of the skin of upper lip was covered by microridges and characterized by
the presence of taste buds and openings of lateral line system. As observed by transmission
electron microscopy, the cytoplasm of the epidermal layers appeared electrondense
except for the superficial layer, where the cytoplasm was electron-lucent and
contained many vacuoles and few profiles of rER. Moreover, the epidermis contained
rodlet cells and stem cells. Few organelles were found within the cytoplasm of club
cells. Neutrophils and eosinophilic granular cells were also demonstrated as important
immune cells in the epidermis of the upper lip. Furthermore, lymphocytes and basophils
could be identified with macrophage in the epidermal layer of the upper lip. Numerous
telocytes were demonstrated between the collagen fibers of the dermis and bundles of
myelinated nerve fibers. In conclusion, the skin of the upper lip region of silver carp displayed
many sensory and immunological characteristic features.

The present study aims to investigate the efficacy of intravenously injected mesenchymal stem cells (MSCs) in treating neuropathic pain
either before or after its induction by a chronic constriction injury (CCI) model. Rats were divided into four groups: control group, neuropathic
group, and treated groups (pre and postinduction) with i.v. mononuclear cells (106 cell/mL). For these rats, experimental testing for
both thermal and mechanical hyperalgesia was evaluated. The cerebral cortex of the rats was dissected, and immunohistochemical analysis
using anti-proliferating cell nuclear antigen (PCNA), CD117, nestin, and glial fibrillary acidic protein was performed. Our results showed
that a single injection of MSCs (either preemptive/or post-CCI) produced equipotent effects on allodynia, mechanical hyperalgesia, and
thermal response. Immunohistochemical analysis showed that the stem cells have reached the cerebral cortex. The injected group with
MSCs before CCI showing few stem cells expressed PCNA, CD117, and nestin in the cerebral cortex. The group injected with MSCs
after CCI, showing numerous recently proliferated CD117-, nestin-, PCNA-positive stem cells in the cerebral cortex. In conclusion, our
findings demonstrate that the most probable effect of i.v. stem cells is the central anti-inflammatory effect, which opens concerns about
how stem cells circulating in systemic administration to reach the site of injury.

Abstract

To understand the development of the mucous preglottal salivary gland in Coturnix japonica (Japanese quail), morphological and histochemical studies were performed on 20 healthy Japanese quail embryos (aging from 10th to 17th incubation days) and 25 healthy quail chicks (aging from 0th to 60th days). The primordia of preglottal salivary gland were observed as an epithelial bud at the early embryonic stage, which then elongated and differentiated into secretory units by the end of this stage. In Japanese quails, the preglottal salivary gland was a mucous polystomatic tubuloalveolar unpaired gland composed of two lateral portions and a middle one embedded into the submucosa of the lingual root. The gland openings accompanied taste pore (8.17 μm) of taste buds associated salivary glands type; some skeletal muscle fibers embedded among secretory lobules extended from muscle cricohyoideus at 14th day-old quail chick. Also, both herbts corpuscles and secretory motor plexus could be detected among secretory lobules. Based on our investigations, the development of the preglottal salivary gland could clearly be distinguished in the embryonic stage into pre bud and bud stages at 10th day old, cord and branching stages ended by cavitation at 11th day old, canalization stage at 13th day old, lobulation and secretory stages by the 17th day old. The secretory materials showed different histochemical reactions ended with highly alcinophilic mucous indicated highly sialomucin (acidic) content. Myoepithelial cells could be demonstrated at a 17-day old quail embryo and thereafter surrounded the secretory endpieces of the preglottal salivary gland.

Keywords: myoepithelial cells; preglottal salivary gland; quails; sialomucin; tubuloalveolar.