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Ultrastructure of the Uterine Cervix
Published in Gabor Huszar, The Physiology and Biochemistry of the Uterus in Pregnancy and Labor, 2020
Ultrastructural studies3,4,21,22 indicate that the expulsion of endocervical secretory products occurs by both the apocrine and the merocrine type of secretory activity (Figures 5 and 6). In apocrine secretions, portions of the apical cytoplasm filled with secretory granules are detached, whereas in the merocrine secretions, the content of apical secretory granules is released through porelike openings of the surface cytoplasmic membrane. Endocervical mucins are synthesized in the Golgi cisternae and in the per-igolgian vesicles3,4,21,22 (Figure 7). The fusion of perigolgian vesicles leads to the formation of larger membrane-bound structures. These, in turn, form by further inter-coalescence large granules with granulo-filamentous mucin content. The Golgi apparatus is associated with free and bound ribosomes and mitochondria, providing the essential protein matrix and energy for the synthesis of mucoproteins. Despite the continuous desquamation of endocervical cells, mitosis in the columnar epithelium is not seen under normal conditions. The mechanism of epithelial mucinous cell renewal is not understood. It is conceivable that new cells are generated from the underlying subcolumnar reserve cells,23 although these are chiefly seen when the endocervical epithelium is exposed to acid pH. Another possible source may be the mature endocervical cells themselves.
Skin and Organs with Epidermoid Mucosae
Published in George W. Casarett, Radiation Histopathology, 2019
The ordinary sweat glands, merocrine in character, are simple, coiled, tubular glands, with the mass of the secretory portion located in the dermis and with narrow, unbranched excretory ducts passing through the epidermis. Resting on the thick basement membrane of the secretory portion are spindle-shaped myoepithelial cells which are thought to aid in the discharge of secretion by contracting. Forming a single layer on the myoepithelial cells are truncated pyramidal cells which excrete the sweat. The epithelial cells of the secretory and duct portions of the sweat glands are relatively specialized cells with numerous mitochondria; these are reverting postmitotic cells and are relatively radioresistant, more resistant that the germinal cells of the sebaceous glands.
Skin and soft tissue
Published in Tor Wo Chiu, Stone’s Plastic Surgery Facts, 2018
Eccrine glands release secretions by exocytosis into ducts; this is also called merocrine secretion. Eccrine sweat glands are smaller than apocrine glands, and the ducts open directly onto the skin surface (unlike apocrine). They are found in highest density in the palms, soles and axilla. The initially isotonic secretions are modified by active NaCl and HCO3 reabsorption in the ducts (which patients with cystic fibrosis are unable to do) to become hypotonic. Their primary function is thermoregulation with sympathetic cholinergic innervation; emotional stressors tend to induce sweating in the palms/soles.
Lacrimal Gland and Orbital Lesions in LatY136F Knock-in Mice, a Model for Human IgG4-Related Ophthalmic Disease
Published in Current Eye Research, 2022
Shoko Hamaoka, Masayuki Takahira, Mitsuhiro Kawano, Kazunori Yamada, Kiyoaki Ito, Tetsuhiko Okuda, Sachiyo Hatake, Marie Malissen, Bernard Malissen, Kazuhisa Sugiyama
Interestingly, we found that IgG1-positive cells also infiltrate the Harderian glands, a merocrine sebaceous gland in mice. The sebaceous glands in the human eyelid are the Meibomian and Zeis glands, and both are holocrine sebaceous gland. There is no human counterpart for the Harderian glands in mice. To date, there is little known about IgG4-related lesions in the sebaceous glands of the human eyelid. However, previous studies have reported cases of swollen eyelid tarsi with IgG4-positive plasma cell infiltration,15–17 indicating that human sebaceous glands could also be affected in IgG4-related disease. Based on the infiltration of IgG1-positive cells in the Harderian glands of LatY136F knock-in mice, we propose that more attention should be placed on the involvement of the Meibomian gland in human IgG4-related ophthalmic disease.