Tumors of the Urinary Bladder in Domesticated Animals
George T. Bryan, Samuel M. Cohen in The Pathology of Bladder Cancer, 2017
Adenomas are composed of a large number of glandular structures separated from one another by a variable amount of connective tissue. The epithelium forming the glands consists of a single layer of columnar cells. The amount of mucin in the epithelial cells varies. In some there is only a small amount situated in the cell substance nearest the lumen, whereas in others there is an amount large enough to produce goblet-type cells. Frequently the glands are distended into thin-walled cystic spaces filled with mucin and desquamated cells. The arrangement of the cells lining the glands is orderly and mitotic figures are exceedingly rare. Adenomas do not invade the muscular layers of the bladder wall. They develop either from the preexisting glands in the mucosa or from the transitional cell epithelium through metaplastic changes. The most common adenomas in cattle and dogs are those of metaplastic origin. Endometrial or nephrogenic adenomas have not been reported in animals.
Histogenesis of Irreversible Changes in the Female Genital Tract After Perinatal Exposure to Hormones and Related Substances
Takao Mori, Hiroshi Nagasawa in Toxicity of Hormones in Perinatal Life, 2020
Based on results from several different types of studies, researchers concluded that the pseudostratified columnar epithelium in the mouse Mullerian vagina undergoes a transformation into a squamous epithelium.2 Parallel with this transformation is a high mitotic activity. Cells arising in the columnar epithelium migrate basally, forming a basal epithelial zone of small cuboidal cells which are the origin of the adult squamous epithelium. Superficially in the epithelium, there is a zone of remaining columnar cells. Under estrogen stimulation, the cells in the basal zone proliferate and cornify with shedding of the superficial columnar cells. The transformation progresses into the CCC until it reaches the level of the squamo-columnar junction, situated in the uppermost part of the CCC of the NMRI mouse strain used in our laboratory. Vaginal morphogenesis is similar in the mouse and the rat but initial stages occurring in the mouse after birth appear in the rat shortly before birth.
The Many Faces of Neoplasia
Jeremy R. Jass in Understanding Pathology, 2020
Columnar epithelium lines the gastrointestinal tract (stomach, small intestine and large intestine) as well as the lung. The gut serves to absorb nutrients but also secretes mucus and digestive enzymes. Tissues that secrete are described as glandular and a simple gland is shaped like a microscopic flask or test tube and is lined by columnar or cuboidal epithelium. The secretions pass into the central space or lumen of the gland and then pour into the gut cavity. Carcinomas arising in such glandular tissues are called adenocarcinomas, and are recognised by the presence of gland-like structures which secrete mucus. Cystic spaces with mucoid contents may be apparent on gross inspection of the cut surface. Adenocarcinomas also arise from solid (as opposed to tube-like) organs that are essentially glandular in structure. Examples are the prostate, pancreas, breast and endocrine glands. Adenocarcinomas are graded as well, moderately and poorly differentiated on the basis of gland formation (Fig. 28).
Gingival epithelial barrier: regulation by beneficial and harmful microbes
Published in Tissue Barriers, 2019
Naoki Takahashi, Benso Sulijaya, Miki Yamada-Hara, Takahiro Tsuzuno, Koichi Tabeta, Kazuhisa Yamazaki
Distinct from the oral epithelium, the gastrointestinal epithelium is composed of a simple layer of columnar epithelial cells. Goblet cells are a major secretory cellular lineage in the intestinal epithelium, synthesizing and secreting mucin into the intestinal lumen. Among other lineages of intestinal epithelial cells, enterocytes are involved in nutrient absorption and immunoglobulin secretion, and Paneth cells can synthesize and produce antimicrobial peptides.23 These specialized epithelial cells are efficient physical and chemical barriers against invading microbes. Unlike the gut, the oral epithelium consists of a stratified squamous epithelium which can be subdivided into three components based on cell morphology: oral epithelium (OE), sulcular epithelium (SE), and junctional epithelium (JE).24 The OE is a keratinizing form of epithelium, providing an effective physical barrier against microbial invasion of the underlying gingival connective tissue. In contrast, SE and JE are dominated by a non-keratinized epithelium,25 which suggests that those epithelia are semipermeable and, thus, allow the transport of macro substances from the gingival sulcus into the underlying connective tissue.
Histological study of the effect of granulocyte colony-stimulating factor on experimentally induced corneal burn in adult male albino rats
Published in Ultrastructural Pathology, 2020
Shereen Shawky Elabd, Suzan E. Abo-Elnasr, Gehan M. Soliman, Naglaa I. Sarhaan, Sadika M. Tawfik
Examination of ultrathin sections obtained from corneal specimens of control rats showed a normal histological structure of the cornea. The epithelium appeared to be formed of basal columnar cells, intermediate layers of polygonal cells, and superficial layers of squamous cells. Hemidesmosomes were observed between the basal surfaces of the basal cells and the basement membrane and beneath the corneal epithelium was Bowman’s Layer. It was a noncellular layer consisting of collagen fibers arranged in an apparently random manner (Figure 6a). The avascular corneal stroma appeared below Bowman’s Layer. It was formed of well-organized collagen fibrils in the form of lamellae oriented at right angles to each other. The attenuated keratocytes appeared spindle shaped with oval nuclei and long process (Figure 6b). Descemet’s membrane was seen as a homogenous noncellular layer interposed between the stroma and the underlying endothelium. The endothelium was seen as a continuous single layer of flat endothelial cells with flat oval euchromatic nuclei representing the posterior surface of the cornea (Figure 6c).
Eye Make-up Products and Dry Eye Disease: A Mini Review
Published in Current Eye Research, 2022
Mazyar Yazdani, Katja Benedikte Prestø Elgstøen, Tor Paaske Utheim
Tear fluid and particles attached to the ocular surface are drained by the nasolacrimal duct into the inferior meatus of the nose. Anatomically, the lacrimal passages are divided into bony and membranous lacrimal sections. The latter include the lacrimal canaliculi, lacrimal sac, and the nasolacrimal duct. The last two parts are lined by a double-layered epithelium containing superficial columnar cells and basal flattened cells. Goblet cells may also be present in the epithelial layer. During blinking, tears are wiped and pushed into the lacrimal puncta, small openings located in the nasal upper and lower eyelids. The punctum ends in the canaliculus, where the fluid drains into the lacrimal sac followed by the nasolacrimal duct canal before reaching the nasal cavity.31