Francesca Testa Riva

Exocytosis in human salivary glands visualized by high-resolution scanning electron microscopy

Abstract The luminal membrane of salivary acinar cells creates a specialized cell surface area that accepts exocytosis and undergoes dynamic changes during secretion. These changes were visualized three-dimensionally from both the inside and outside of the cell in human parotid and submandibular glands, by application of in vitro secretory stimulation and then of OsO4 maceration to remove cytoplasmic organelles by varying degrees. In control glands treated without secretagogues, the luminal surface of serous acinar cells bore well-developed microvilli with only an occasional incidence of exocytotic profiles. Following treatment with the β-adrenergic agonist, isoproterenol, considerable shortening and loss of microvilli occurred along the luminal membrane where, on its cytoplasmic side, many protuberances of sizes similar to or smaller than those of single secretory granules (∼1 μm in diameter) appeared. The cytoplasmic surface of these protuberances exhibited small vesicles (∼100–150 nm in diameter) that, by transmission electron microscopy, were shown to be coated pits or vesicles present on or around the exocytosed granule membranes. Treatment of tissues with the muscarinic agonist carbachol also caused a decrease of microvilli and the appearance of protrusions at the luminal membrane. However, unlike isoproterenol treatment, many of these protrusions were devoid of small pits or vesicles and were much larger than a single secretory granule. These results indicate that (1) secretory stimulation causes the dynamic transformation of microvilli at the luminal membrane, where granule docking and membrane fusion take place, and (2) after fusion, the exocytosed membranes are processed differently, by coated pit/vesicle mediated or non-mediated mechanisms, according to the autonomic receptor control.

Normal human salivary glands

The human salivary glands comprise the major and minor salivary glands. The major salivary glands are encased by a fibrous capsule and are connected to the oral cavity by long excretory ducts. The minor salivary glands are abundant in the tongue and in the walls of the oral cavity; their excretory ducts are short. There are three paired sets of major glands: parotid, submandibular, and sublingual and several hundreds of minor salivary glands, which are named according to their location: buccal, labial, lingual, palatine, and glossopalatine.

Iulius Casserius (1552-1616): The self-made anatomist of Padua's golden age

Giulio Cesare Casseri (1552– 1616), whose name was Latinized into Iulius Casserius, was born in Piacenza; therefore, the nickname Piacentino (Placentinus) was often used. According to Sterzi (1910), who based his claim on a statement contained in Casserius’s will, his date of birth was around 1552. It should be noted, however, that although most modern authors accept this date (Roberts and Tomlinson, 1992; Premuda, 1993), some (Singer, 1957) still report 1561 as his birth date on the basis of the inscription (Fig. 1) appearing on the portrait published in Casserius’s work De Vocis Auditusque organis that ascribes to the author the age of 39 years. According to most of his early biographers (Tomasini, 1630; Ghilini, 1647; Papadopoli, 1726), Casserius’s family was very poor and the young Iulius, perhaps as the servant of some student (Sterzi, 1910), moved to Padua, the city that shared with Bologna the reputation of being the seat of Italy’s most illustrious university. He soon assumed the job of servant in the house of the famed Gerolamo Fabrici d’Acquapendente (Fabricius, 1533– 1619) (Fig. 2), Public Lecturer of Anatomy and Surgery (Tomasini, 1630; Ghilini, 1647). As Tomasini (1630) reports, “from a servant he became first Fabricius’s auditor, then instructor and brilliant disciple.” We do not know when Casserius matriculated in the School of Medicine of the Universita Artista. As mentioned several times in his works, Casserius, in addition to Fabricius, had the well-known physician Gerolamo Mercuriale (Mercurialis) as a teacher and mentor, who held the chair of Clinical Medicine of Padua in the years 1569–1587. The precise date he obtained his degree in medicine and philosophy is unknown, because the official records are missing from 1580 to 1587; a likely date is ca.1580 (Sterzi, 1910; De Ferrari, 1978; Premuda, 1993). After the award of his degree, Casserius, in addition to giving private lectures on anatomy to the students of the Universita Artista and working as Fabricius’s preparator, started a practice as physician and surgeon in Padua that was very successful (Tomasini, 1630). In 1584, Casserius’s reputation was already so great that he took Fabricius’s place as member of the board of examiners for the finals in surgery. These examinations, held in private houses in the presence of the Rector of the University, conferred the license to practice surgery. The profession of surgery was considered in those days as a minor branch of Medicine and the surgeon had to take an oath that he would not involve himself in the treatment of serious diseases, but would call a licensed physician whenever the patient was in real danger.

Ciliated Cells in the Main Excretory Duct of the Submandibular Gland in Obstructive Sialadenitis: A SEM and TEM Study

The epithelium of the main excretory duct of the submandibular gland in five cases of obstructive sialadenitis was studied by TEM and SEM. In three cases we found a considerable increase in goblet and ciliated cells. As well as normal cilia, different kinds of ciliary anomalies, especially compound cilia, were noticed. Images of centriole formation and of ciliogenesis, both normal and abnormal, were also observed. Several hypotheses concerning the mode of formation of the compound cilia are discussed.

Cytomorphological study on human submandibular gland following treatment with secretagogue drugs

Using specimens of human submandibular glands, we have investigated in vitro the morphological modifications induced by clozapine, a dibenzodiazepine derivative that is used in psychotic patients and that provokes hypersalivation, a side-effect of therapy. The effects of the drug, used alone or in combination with carbachol, have been compared with those observed after treatment with drugs acting on specific receptors. To quantify the response to stimulation, we have calculated (with statistical methods) the number of microvilli and microbuds (corresponding to pits seen in images obtained by transmission electron microscopy) per square micrometre of the cytoplasmic surface of the intercellular canaliculi luminal membrane in images obtained by high-resolution scanning electron microscopy. Clozapine, when directly acting on human submandibular specimens, induces a small secretory response in serous cells; this is partially decreased by muscarinic and adrenergic antagonists and by combined incubation with carbachol, thus confirming its behaviour as a partial agonist to muscarinic receptors. We also suggests that the drug acts on the nerve terminals contained within the glandular specimens.

Giuseppe Sterzi (1876 -1919) of the University of Cagliari: A Brilliant Neuroanatomist and Medical Historian

irst of all, let me explain why weare now writing about Sterzi.Approximately two years ago I(A.R.) received a message from Prof.Colin Wendell Smith, the secretary ofthe FCAT, who happens to live in theantipodal (for me) island of Tasma-nia, asking me if I could find him thearticle on subcutaneous tissue writtenby an Italian professor named Sterzi.This article had been mentioned byProf. DiDio during one FCAT meetingand Prof. Wendell Smith had alreadyunsuccessfully tried to obtain it viathe usual library system. Since I wasaware that Sterzi had been one of mypredecessors in the Anatomy Chair inCagliari, it was easy for me to send acopy of the article to Prof. WendellSmith, who was surprised to hear thatSterzi had been working in the antip-odal (for him) island of Sardinia andso was indirectly associated with me.In order to provide him with an En-glish summary, I had to read the 172-page article myself. I was greatly im-pressed by the rigorous discussion ofprevious reports and by the amount ofnew findings obtained also through acomparative anatomical/embryologi-cal approach. Prompted by this, webecame interested in Sterzi’s life andscientific achievements, being mani-fest that the studies on the subcutane-ous tissue and some others such asthat on the endolymphatic sac,though important and superbly car-ried out, had been just a parenthesisin his production devoted almost ex-clusively to neuroanatomy and thehistory of anatomy. Favaro (1921)maintains, in fact, that Sterzi madethem mainly to show his critics thathis production was not monothe-matic.

Ultrastructural study of the mental body of Hydromantes genei (Amphibia: Plethodontidae)

The mental glands of Hydromantes genei are considered a specialized form of the urodele serous cutaneous glands. Use of a variety of techniques of maceration and digestion as well as transmission electron microscopy (TEM) and scanning electron microscopy (SEM) has shown the three‐dimensional morphology of secretory and myoepithelial cells. Secretory cells are pyramidal and rest on an almost continuous layer of myoepithelial cells. The latter have a long ribbon‐like body from which branch off transversal and longitudinal processes with swallow‐tailed ends. Cytoplasmic processes of secretory cells, containing irregular dense vesicles, squeeze through clefts between myoepithelial cells and may reach, at some points, the basal lamina. The interstices between myoepithelium and secretory cells are extraordinarily rich in nerve endings with clear vesicles. The glandular outlets appear as elliptical stomata in the superficial layer of the epidermis and are lined by horny cells, which invaginate to circumscribe the excretory duct. The morphological results indicate that the myoepithelium of Plethodontidae mental glands differ in some respects from that of amphibian serous cutaneous glands. A double polarity for the secretory cells is also suggested.