The Cell Biology of Amelogenesis
Colin Robinson, Jennifer Kirkham, Roger Shore in Dental Enamel, 2017
The secretory ameloblast is typical of merocnne secretory cells. The supranuclear compartment has numerous strands of GER oriented parallel to the longitudinal cell axis and an extensive Golgi complex (Figure 9). The GER synthesizes the enamel matrix proteins, the amelogenins, and nonamelogenins,74 which are transported to the Golgi complexes by transitional vesicles.75 Proteinases are also present in secretory enamel matrix76-78 but the mode of synthesis and transport of these enzymes to the enamel matrix has not been determined. Posttranslational glycosylation79 and sulfation80 of the enamel proteins occurs in the Golgi complex where they are also packaged into membrane bound, electron-dense secretory granules approximately 0.25 μm in diameter (Figures 9B and 10),29,81 in the golgi these secretory granules have been shown to contain both the amelogenin and nonamelogenin proteins.27 Secretory granules are then transported to the forming enamel front along microtubules, a process that can be inhibited by antimicrotubule agents such as colchicine82 and vinblastine.83 Secretory granules are exocytosed by a modified merocrine-type secretory mechanism.84 Granules are preferentially released distal to the terminal web to form the interrod enamel and at the Tomes' process tip to form the rod enamel (Figures 9 and 10).61
Normal pubertal development and the menstrual cycle as a vital sign *
Joseph S. Sanfilippo, Eduardo Lara-Torre, Veronica Gomez-Lobo in Sanfilippo's Textbook of Pediatric and Adolescent GynecologySecond Edition, 2019
Pubarche is the physical findings of growth of pubic and axillary hair. Pubarche is caused by adrenarche, which is the increase in adrenal androgens, principally dehydroepiandrosterone (DHEA) and androstenedione.1 Mean onset of pubic hair in nonobese girls is 11.57 years and 11.39 years in obese girls. Pubarche begins at a mean age of 10.65 in non-Hispanic black, 11.6 years in non-Hispanic white, and 11.63 in Mexican American girls.29 As with breast development, SMR is used to describe pubic hair development (Figure 1.6).28 When examining pubic hair, it is important to make note of the distribution of the hair. For example, from the prepubertal stage 1 to stage 2, pubic hair begins to grow along the labia; as maturity continues, growth occurs over the mons pubis; and finally at stage 5, growth has occurred on the medial thigh. During the progression through the SMR, the hair becomes more pigmented, coarser, and curlier. There is no SMR for axillary hair. However, a gross scale of 1 (no hair) to 3 (adult pattern of hair) is sometimes used. There is an increase in the activity of glandular tissue, specifically sebaceous glands and merocrine sweat glands. During the initial appearance of pubic and axillary hair, the apocrine glands begin to function.14
Skin and Organs with Epidermoid Mucosae
George W. Casarett in 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.
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.