Adult Gland Research Articles

Susceptibility and immune response of Catarina scallop (Argopecten ventricosus) against Vibrio parahaemolyticus, the causative agent of AHPND in shrimp

Susceptibility and immune response of Argopecten ventricosus challenged with Vibrio parahaemolyticus were determined. Mortality and median lethal concentration of V. parahaemolyticus were assessed in scallop seeds and adults challenged by immersion. Histopathological analysis was done in adults challenged by immersion. The immune response was analyzed in adults by injecting heat-inactivated bacteria in the adductor muscle. Hemolymph samples were taken at 0, 8, 24, 48, and 72h. Time zero corresponded to samples of scallop hemolymph before challenging with vibrio. In bioassays, scallops were fed with microalgae concentrate Shellfish Diet 1800®. Seeds and adults of A. ventricosus were susceptible to V. parahaemolyticus showing a LC50 of 623CFUmL−1 and 62,853CFUmL−1, respectively. V. parahaemolyticus toxins caused lesions in digestive glands of adults analyzed. Significant variations were observed in hemocyte number, phenoloxidase activity, and lysosomal hydrolytic enzymes, mainly at 8 and 24h, post infection. Results confirm that seeds and adults of A. ventricosus are susceptible to V. parahaemolyticus infection, but seeds are more susceptible than adults. In adults, the immune response of A. ventricosus was modulated by V. parahaemolyticus.

Abstract 5024: Unmasking heterogeneity within the adult mammary stem cell compartment

Abstract Breast cancer is a highly heterogeneous disease at both the molecular and pathological levels. To understand this heterogeneity and ‘cells of origin’ of breast cancer, it is important to dissect the normal mammary epithelial hierarchy. Despite accumulating evidence for a mammary differentiation hierarchy, the basal compartment comprising stem cells remains poorly characterized. Through gene expression profiling of Lgr5+ versus Lgr5– basal epithelial cells, we identify a novel marker that led to the fractionation of three distinct mammary stem cell (MaSC) subsets in the adult gland. These exist in a largely quiescent state but differ in their repopulating ability, spatial localisation, and their molecular signatures. Interestingly, the dormant MaSC subset localises to the proximal region of the gland throughout life. These cells appear to originate from the embryonic mammary primordia before switching to a quiescent state post-natally but can be recruited into the cell cycle in response to hormones. Single cell gene expression analyses have also revealed unexpected complexity within the basal and luminal compartments. Moreover, analyses at different stages of development have provided insights into the earliest ‘lineage priming’ events. Citation Format: Nai Yang Fu, Anne Rios, Bhupinder Pal, Charity Law, Paul Jamieson, Francois Vaillant, Gordon K. Smyth, Matthew E. Ritchie, Geoffrey J. Lindeman, Jane E. Visvader. Unmasking heterogeneity within the adult mammary stem cell compartment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5024. doi:10.1158/1538-7445.AM2017-5024

Cell type-specific localization of Ephs pairing with ephrin-B2 in the rat postnatal pituitary gland.

Sox2-expressing stem/progenitor cells in the anterior lobe of the pituitary gland form two types of micro-environments (niches): the marginal cell layer and dense cell clusters in the parenchyma. In relation to the mechanism of regulation of niches, juxtacrine signaling via ephrin and its receptor Eph is known to play important roles in various niches. The ephrin and Eph families are divided into two subclasses to create ephrin/Eph signaling in co-operation with confined partners. Recently, we reported that ephrin-B2 localizes specifically to both pituitary niches. However, the Ephs interacting with ephrin-B2 in these pituitary niches have not yet been identified. Therefore, the present study aims to identify the Ephs interacting with ephrin-B2 and the cells that produce them in the rat pituitary gland. In situ hybridization and immunohistochemistry demonstrated cell type-specific localization of candidate interacting partners for ephrin-B2, including EphA4 in cells located in the posterior lobe, EphB1 in gonadotropes, EphB2 in corticotropes, EphB3 in stem/progenitor cells and EphB4 in endothelial cells in the adult pituitary gland. In particular, double-immunohistochemistry showed cis-interactions between EphB3 and ephrin-B2 in the apical cell membranes of stem/progenitor cell niches throughout life and trans-interactions between EphB2 produced by corticotropes and ephrin-B2 located in the basolateral cell membranes of stem/progenitor cells in the early postnatal pituitary gland. These data indicate that ephrin-B2 plays a role in pituitary stem/progenitor cell niches by selective interaction with EphB3 in cis and EphB2 in trans.

Unusual neoplasm on the hard palate of a child: a case report

BackgroundMyoepitheliomas account for less than 1% of salivary gland tumors. They mostly affect the parotid glands of adults during the third to fifth decades.Case presentationA 10-year-old Indian boy reported a small swelling in the roof of his mouth of 10 days’ duration. History revealed that the lesion was painless and not associated with bleeding or pus discharge. On examination, a purplish well-circumscribed growth was noted on his posterior hard palate. Magnetic resonance imaging was suggestive of a well-encapsulated hemangioma. An excisional biopsy was performed and histopathology along with immunohistochemistry analysis showed that the lesion was a spindle cell variant of benign myoepithelioma.ConclusionPalatal myoepitheliomas are rare and their occurrence in young individuals is rarer.

Prognostic implication of GATA3 gene mutation on survival in invasive ductal carcinoma of the breast.

e13114 Background: GATA3 encodes a transcription factor, which is involved in activation and suppression of genes involved in cell maturation. GATA3 is necessary in the adult mammary gland to maintain the integrity and function of the luminal epithelium. Methods: METABRIC project funded by cancer research UK, the British Columbia cancer foundation and the Canadian breast cancer foundation mapped 173 gene mutations and amplifications in 2,433 primary breast tumors. Retrospective analysis was done for patients with invasive ductal carcinoma of the breast in the age group 30-60; to study the effect of GATA3 mutation on survival. Median survival was obtained from Kaplan-Meier plot, and mortality between groups was compared by Odds ratio (OR). Results: A total of 1500 patients across all age groups had invasive ductal carcinoma. 650 were within the age group 30-60; of which 234 died due to the disease, 360 were alive and 55 died due to other causes. 398 patients (61.2%) tested positive for estrogen receptor (ER) and 521 patients (80.2%) were negative for HER2 (human epidermal growth factor receptor 2). TP53 (50%) and PIK3CA (36%) mutations were more prevalent. GATA3 mutation was found in 79 patients (12.34%); among which, all 79 patients tested positive for ER (100%) and 74 patients (94.9%) negative for HER2. 10 patients (12.7%) died due to the disease, 62 patients (78.5%) were alive and 7 patients (8.9%) died due to other causes. Hence, patients with GATA3 mutations were more likely to survive (OR 4.66; CI 2.33-9.29 p < 0.0001) than patients without the mutation. The median survival for patients with GATA3 mutation (300 months) was also greater than patients without the mutation (219 months). In addition, patients with GATA3 mutation were more likely to be ER positive and HER2 negative. Conclusions: In the mammary gland, GATA3 is required for luminal epithelial cell differentiation. Loss of GATA3 results in de-differentiation to stem cell phenotype. It is found that GATA3 mutation correlates with a better prognosis compared to more common TP53 and PIK3CA gene mutations.

Stage and tissue expression patterns of Schistosoma mansoni venom allergen-like proteins SmVAL 4, 13, 16 and 24

BackgroundSchistosoma mansoni venom allergen-like protein (SmVAL) is a gene family composed of 29 members divided into group 1 encoding proteins potentially secreted, and group 2 encoding intracellular components. Some members were found to be upregulated in the transition of germ ball - cercariae - day 3 schistosomula, suggesting that group 1 SmVAL proteins are associated with the invasion of the human host, although their functions are not completely established. Recently, we have described the localization of SmVAL7 (group 1) and SmVAL6 (group 2) transcripts in the oesophageal gland and in the oral and ventral suckers of adult parasites, respectively. The expression patterns of the two genes suggest that SmVAL7 protein plays a role in the blood-feeding process while SmVAL6 is associated with the parasite attachment and movement in the vasculature. In this way, searching for additional secreted SmVAL proteins that could be involved in key processes from skin penetration to the beginning of blood-feeding, we investigated the tissue localization of SmVAL4, 13, 16 and 24 by whole-mount in situ hybridization (WISH).ResultsWe report here the localization of group 1 SmVAL4 and 24 transcripts in the pre-acetabular glands of developing germ balls. Time course experiments of in vitro cultured schistosomula after cercariae transformation demonstrated that SmVAL4 protein is secreted during the first 3 h of in vitro culture, correlating with the emptying of acetabular glands as documented by confocal microscopy. In addition, the localization of SmVAL13 transcripts in adult male anterior oesophageal gland suggests that the respective protein may be involved in the first steps of the blood-feeding process. SmVAL16 was localized close to the neural ganglia and requires further investigation.ConclusionsOur findings demonstrate that SmVAL proteins have localizations that place them in strategic positions to be considered as potential vaccine candidates as some members are exposed to interaction with the immune system and may participate in key processes of mammalian invasion and parasitism establishment.

Morphogenesis of honeybee hypopharyngeal gland during pupal development

BackgroundThe hypopharyngeal gland of worker bees contributes to the production of the royal jelly fed to queens and larvae. The gland consists of thousands of two-cell units that are composed of a secretory cell and a duct cell and that are arranged in sets of about 12 around a long collecting duct.ResultsBy fluorescent staining, we have examined the morphogenesis of the hypopharyngeal gland during pupal life, from a saccule lined by a pseudostratified epithelium to the elaborate organ of adult worker bees. The hypopharyngeal gland develops as follows. (1) Cell proliferation occurs during the first day of pupal life in the hypopharyngeal gland primordium. (2) Subsequently, the epithelium becomes organized into rosette-like units of three cells. Two of these will become the secretory cell and the duct cell of the adult secretory units; the third cell contributes only temporarily to the development of the secretory units and is eliminated by apoptosis in the second half of pupal life. (3) The three-cell units of flask-shaped cells undergo complex changes in cell morphology. Thus, by mid-pupal stage, the gland is structurally similar to the adult hypopharyngeal gland. (4) Concomitantly, the prospective secretory cell attains its characteristic subcellular organization by the invagination of a small patch of apical membrane domain, its extension to a tube of about 100 μm in length (termed a canaliculus), and the expansion of the tube to a diameter of about 3 μm. (6) Finally, the canaliculus-associated F-actin system becomes reorganized into rings of bundled actin filaments that are positioned at regular distances along the membrane tube.ConclusionsThe morphogenesis of the secretory units in the hypopharyngeal gland of the worker bee seems to be based on a developmental program that is conserved, with slight modification, among insects for the production of dermal glands. Elaboration of the secretory cell as a unicellular seamless epithelial tube occurs by invagination of the apical membrane, its extension likely by targeted exocytosis and its expansion, and finally the reorganisation of the membrane-associated F-actin system. Our work is fundamental for future studies of environmental effects on hypopharyngeal gland morphology and development.

Regeneration of thyroid follicles from primordial cells in a murine thyroidectomized model

The functional unit of the thyroid gland, the thyroid follicle, dynamically responds to various stimuli to maintain thyroid hormone homeostasis. However, thyroid follicles in the adult human thyroid gland have a very limited regenerative capacity following partial resection of the thyroid gland. To gain insight into follicle regeneration in the adult thyroid gland, we observed the regeneration processes of murine thyroid follicles after partial resection of the lower third of the thyroid gland in 10-week-old male C57BL/6 mice. Based on sequential observation of the partially resected thyroid lobe, we found primitive follicles forming in the area corresponding to the central zone of the intact lateral thyroid lobe. The primitive thyroid follicles were multiciliated and had coarsely vacuolated cytoplasm and large vesicular nuclei. Consistently, these primitive follicular cells did not express the differentiation markers paired box gene-8 and thyroid transcription factor-1 (clone SPT24), but were positive for forkhead box protein A2 and leucine-rich repeat-containing G-protein-coupled receptor 4/GPR48. Follicles newly generated from the primitive follicles had clear or vacuolar cytoplasm with dense, darkly stained nuclei. At day 21 after partial thyroidectomy, the tall cuboidal follicular epithelial cells had clear or vacuolar cytoplasm, and the intraluminal colloid displayed pale staining. Smaller activated follicles were found in the central zone of the lateral lobe, whereas larger mature follicles were located in the peripheral zone. Based on these observations, we propose that the follicle regeneration process in the partially resected adult murine thyroid gland associated with the appearance of primitive follicular cells may be a platform for the budding of differentiated follicles in mice.

Identification of quiescent and spatially restricted mammary stem cells that are hormone responsive.

Despite accumulating evidence for a mammary differentiation hierarchy, the basal compartment comprising stem cells remains poorly characterized. Through gene expression profiling of Lgr5+ basal epithelial cells, we identify a new marker, Tetraspanin8 (Tspan8). Fractionation based on Tspan8 and Lgr5 expression uncovered three distinct mammary stem cell (MaSC) subsets in the adult mammary gland. These exist in a largely quiescent state but differ in their reconstituting ability, spatial localization, and their molecular and epigenetic signatures. Interestingly, the deeply quiescent MaSC subset (Lgr5+Tspan8hi) resides within the proximal region throughout life, and has a transcriptome strikingly similar to that of claudin-low tumours. Lgr5+Tspan8hi cells appear to originate from the embryonic mammary primordia before switching to a quiescent state postnatally but can be activated by ovarian hormones. Our findings reveal an unexpected degree of complexity within the adult MaSC compartment and identify a dormant subset poised for activation in response to physiological stimuli.

Molecular Profiling of the Developing Lacrimal Gland Reveals Putative Role of Notch Signaling in Branching Morphogenesis.

PurposeAlthough normal function of the lacrimal gland is essential for vision (and thus for human well-being), the lacrimal gland remains rather poorly understood at a molecular level. The purpose of this study was to identify new genes and signaling cascades involved in lacrimal gland development.MethodsTo identify these genes, we used microarray analysis to compare the gene expression profiles of developing (embryonic) and adult lacrimal glands. Differential data were validated by quantitative RT-PCR, and several corresponding proteins were confirmed by immunohistochemistry and Western blot analysis. To evaluate the role of NOTCH signaling in lacrimal gland (LG) development, we used the NOTCH inhibitor DAPT and conditional Notch1 knockouts.ResultsOur microarray data and an in silico reconstruction of cellular networks revealed significant changes in the expression patterns of genes from the NOTCH, WNT, TGFβ, and Hedgehog pathways, all of which are involved in the regulation of epithelial-to-mesenchymal transition (EMT). Our study also revealed new putative lacrimal gland stem cell/progenitor markers. We found that inhibiting Notch signaling both increases the average number of lacrimal gland lobules and reduces the size of each lobule.ConclusionsOur findings suggest that NOTCH-, WNT-, TGFβ-, and Hedgehog-regulated EMT transition are critical mechanisms in lacrimal gland development and morphogenesis. Our data also supports the hypothesis that NOTCH signaling regulates branching morphogenesis in the developing lacrimal gland by suppressing cleft formation.

Defining epithelial cell dynamics and lineage relationships in the developing lacrimal gland.

The tear-producing lacrimal gland is a tubular organ that protects and lubricates the ocular surface. The lacrimal gland possesses many features that make it an excellent model in which to investigate tubulogenesis, but the cell types and lineage relationships that drive lacrimal gland formation are unclear. Using single-cell sequencing and other molecular tools, we reveal novel cell identities and epithelial lineage dynamics that underlie lacrimal gland development. We show that the lacrimal gland from its earliest developmental stages is composed of multiple subpopulations of immune, epithelial and mesenchymal cell lineages. The epithelial lineage exhibits the most substantial cellular changes, transitioning through a series of unique transcriptional states to become terminally differentiated acinar, ductal and myoepithelial cells. Furthermore, lineage tracing in postnatal and adult glands provides the first direct evidence of unipotent KRT5+ epithelial cells in the lacrimal gland. Finally, we show conservation of developmental markers between the developing mouse and human lacrimal gland, supporting the use of mice to understand human development. Together, our data reveal crucial features of lacrimal gland development that have broad implications for understanding epithelial organogenesis.

Notch Signaling and Maintenance of SOX2 Expression in Rat Anterior Pituitary Cells.

After publication of reports describing the presence of stem/progenitor cells among non-hormone-producing cells in the pituitary, the mechanism responsible for proliferation and differentiation generated considerable interest. Several studies have suggested that Notch signaling is involved. In the present study, we examined the histochemical relationship between Notch signaling molecules and the transcription factor SOX2 in rat pituitary. Combined in situ hybridization and immunohistochemistry showed that Notch2 mRNA and SOX2 were co-expressed at embryonic day 14.5 in most cells in the adenohypophyseal primordium. In adult rat pituitary, double immunohistochemistry showed that SOX2 and either Notch2 or the Notch signaling target HES1 were co-localized within cells with large oval nuclei in both the marginal cell layer and cell aggregates in the main part of the anterior lobe, which are believed to be stem cell niches. Furthermore, when the Notch signaling inhibitor DAPT was added to a primary culture of adult rat anterior pituitary cells, the proportion of SOX2-expressing cells within Notch2-positive cells was approximately 30% lower. These findings suggest that Notch signaling has a role in maintaining the stemness of precursor cells in the adult rat pituitary gland.

Crying a river: how much salt-laden jelly can a leatherback turtle really eat?

Leatherback turtles (Dermochelys coriacea) are capital breeders that accumulate blubber (33 kJ g-1 wet mass) by hyperphagia on a gelatinous diet at high latitudes; they breed in the tropics. A jellyfish diet is energy poor (0.1-0.2 kJ g-1 wet mass) so leatherbacks must ingest large quantities. Two published estimates of feeding rate [50% body massday-1 (on Rhizostoma pulmo) and 73% body massday-1 (on Cyanea capillata)] have been criticised as too high. Jellyfish have high salt and water contents that must be removed to access organic material and energy. Most salt is removed (as NaCl) by paired lachrymal salt glands. Divalent ions are lost via the gut. In this study, the size of adult salt glands (0.622 kg for a 450 kg turtle; relatively three times the size of salt glands in cheloniid turtles) was measured for the first time by computed tomography scanning. Various published values for leatherback field metabolic rate, body fluid composition and likely blubber accumulation rates are combined with known jellyfish salt, water and organic compositions to calculate feasible salt gland secretion rates and feeding rates. The results indicate that leatherbacks can produce about 10-15 ml secretion g-1 salt gland massh-1 (tear osmolality 1800 mOsm kg-1). This will permit consumption of 80% body massday-1 of Ccapillata Calculations suggest that leatherbacks will find it difficult/impossible to accumulate sufficient blubber for reproduction in a single feeding season. Rapid jellyfish digestion and short gut transit times are essential.

BPI-fold (BPIF) containing/plunc protein expression in human fetal major and minor salivary glands.

The aim of this study was to determine expression, not previously described, of PLUNC (palate, lung, and nasal epithelium clone) (BPI-fold containing) proteins in major and minor salivary glands from very early fetal tissue to the end of the second trimester and thus gain further insight into the function of these proteins. Early fetal heads, and major and minor salivary glands were collected retrospectively and glands were classified according to morphodifferentiation stage. Expression of BPI-fold containing proteins was localized through immunohistochemistry. BPIFA2, the major BPI-fold containing protein in adult salivary glands, was detected only in the laryngeal pharynx; the lack of staining in salivary glands suggested salivary expression is either very late in development or is only in adult tissues. Early expression of BPIFA1 was seen in the trachea and nasal cavity with salivary gland expression only seen in late morphodifferentiation stages. BPIFB1 was seen in early neural tissue and at later stages in submandibular and sublingual glands. BPIFA1 is significantly expressed in early fetal oral tissue but BPIFB1 has extremely limited expression and the major salivary BPIF protein (BPIFA2) is not produced in fetal development. Further studies, with more sensitive techniques, will confirm the expression pattern and enable a better understanding of embryonic BPIF protein function.

A histological autopsy study of the thyroid gland in HIV infected adults at the University Teaching Hospital in Lusaka, Zambia

Background: Despite the high prevalence of Human Immunodeficiency Virus (HIV) in Zambia, not much is known about the spectrum of thyroid lesions in patients with Acquired Immune Deficiency Virus, (AIDS). Patients with AIDS have increased prevalence of thyroid function abnormalities. It is therefore postulated the thyroid gland would be involved in AIDS patients. This study focused on the histologic appearances of the thyroid gland in HIV and AIDS patients on post mortem. The findings will provide evidence based recommendations on the management of thyroid diseases in the HIV infected in Zambia.
 Objective: The aim of the study was to determine the histological appearances of adult thyroid glands in patients who died of HIV related diseases at UTH in the period 2010 to 2012.
 Materials and Methods: This research was a descriptive retrospective study of adult thyroid glands collected at autopsy during the period 2010 to 2012. The study took place at the University Teaching Hospital (UTH) in the Department of Pathology and Microbiology in Lusaka, Zambia. A total of 200 thyroid gland paraffin blocked samples were obtained from the parent study tissue bank by convenient sampling. The inclusion criteria included samples from adult HIV patients who were admitted to UTH and died in hospital. The Paraffin blocked thyroid tissue samples were processed according to standard histopathology laboratory protocols at UTH which included sectioning and staining with hematoxylin and eosin. The slides were examined at light microscopic level. Clinical data was obtained from the available case notes.
 Results: The sample size was 200 thyroid glands of which 123(62%) were males. Thyroid histopathological lesions were seen in 111 (56%) of the cases, of which 60 (54%) were male. The lesions included: Interstitial fibrosis 104 (52%), nonspecific chronic thyroiditis 42 (21%). Infectious diseases included Mycobacterium tuberculosis 2 (1%) and Cryptococcus neoformans 1(0.5%).
 Conclusion: These findings outline the importance of thyroid function testing in HIV infected patients who may have subclinical thyroid dysfunction and infection.

Submandibular gland biometry by high frequency ultrasound

IntroductionSubmandibular glands are involved in many disease processes. Acute viral and bacterial inflammatory diseases are the most common causes of submandibular gland enlargement. Reduction in their size is observed in chronic inflammation and after radiation therapy. Various benign and malignant neoplasms also affect them. Therefore it is important to know the normal range of measurements as a reference. High frequency ultrasound is an easily available and reliable radiological investigation used for primary evaluation of the submandibular glands. The study was conducted to determine biometry of submandibular gland in healthy adults by high frequency ultrasound. MethodsTotal 100 subjects from third to seventh decade underwent high frequency ultrasound of submandibular gland. There were equal numbers of both genders in each decade. Length, depth, width and volume of both glands were recorded. ResultThe mean antero-posterior length was 3.26±0.34cm, paramandibular depth was 1.74±0.27cm and lateral-medial width (transverse) was 2.23±0.37cm. Volume measurement by ultrasound was 7.06±2.51ml. DiscussionMeasurement of size and volume of submandibular gland is now easily possible with the help of high frequency ultrasound. These can be used as reference value in determining increase or reduction in size of the gland in various disorders.

Bilateral adrenal histoplasmosis in an immunocompetent man from Texas

Disseminated histoplasmosis affecting the adrenal gland(s) of immunocompetent adults is a very rare infection. Here, we present a case of bilateral adrenal histoplasmosis in an immunocompetent, 62-year-old gentleman from Texas along with a brief review of the published literature. Given the risk of patient decompensation secondary to adrenal insufficiency and the wide availability of effective treatments, adrenal histoplasmosis must be considered even in immunocompetent adults who acquire adrenal masses.

Genetically Blocking the Zebrafish Pineal Clock Affects Circadian Behavior.

The master circadian clock in fish has been considered to reside in the pineal gland. This dogma is challenged, however, by the finding that most zebrafish tissues contain molecular clocks that are directly reset by light. To further examine the role of the pineal gland oscillator in the zebrafish circadian system, we generated a transgenic line in which the molecular clock is selectively blocked in the melatonin-producing cells of the pineal gland by a dominant-negative strategy. As a result, clock-controlled rhythms of melatonin production in the adult pineal gland were disrupted. Moreover, transcriptome analysis revealed that the circadian expression pattern of the majority of clock-controlled genes in the adult pineal gland is abolished. Importantly, circadian rhythms of behavior in zebrafish larvae were affected: rhythms of place preference under constant darkness were eliminated, and rhythms of locomotor activity under constant dark and constant dim light conditions were markedly attenuated. On the other hand, global peripheral molecular oscillators, as measured in whole larvae, were unaffected in this model. In conclusion, characterization of this novel transgenic model provides evidence that the molecular clock in the melatonin-producing cells of the pineal gland plays a key role, possibly as part of a multiple pacemaker system, in modulating circadian rhythms of behavior.

Cellular Basis of Pineal Gland Development: Emerging Role of Microglia as Phenotype Regulator.

The adult pineal gland is composed of pinealocytes, astrocytes, microglia, and other interstitial cells that have been described in detail. However, factors that contribute to pineal development have not been fully elucidated, nor have pineal cell lineages been well characterized. We applied systematic double, triple and quadruple labeling of cell-specific markers on prenatal, postnatal and mature rat pineal gland tissue combined with confocal microscopy to provide a comprehensive view of the cellular dynamics and cell lineages that contribute to pineal gland development. The pineal gland begins as an evagination of neuroepithelium in the roof of the third ventricle. The pineal primordium initially consists of radially aligned Pax6+ precursor cells that express vimentin and divide at the ventricular lumen. After the tubular neuroepithelium fuses, the distribution of Pax6+ cells transitions to include rosette-like structures and later, dispersed cells. In the developing gland all dividing cells express Pax6, indicating that Pax6+ precursor cells generate pinealocytes and some interstitial cells. The density of Pax6+ cells decreases across pineal development as a result of cellular differentiation and microglial phagocytosis, but Pax6+ cells remain in the adult gland as a distinct population. Microglial colonization begins after pineal recess formation. Microglial phagocytosis of Pax6+ cells is not common at early stages but increases as microglia colonize the gland. In the postnatal gland microglia affiliate with Tuj1+ nerve fibers, IB4+ blood vessels, and Pax6+ cells. We demonstrate that microglia engulf Pax6+ cells, nerve fibers, and blood vessel-related elements, but not pinealocytes. We conclude that microglia play a role in pineal gland formation and homeostasis by regulating the precursor cell population, remodeling blood vessels and pruning sympathetic nerve fibers.

Fetal Exposure to Low Levels of the Plasticizer DEHP Predisposes the Adult Male Adrenal Gland to Endocrine Disruption.

In utero exposure to endocrine disrupting chemicals (EDCs) may affect adult health. Di-(2-ethylhexyl) phthalate (DEHP) is an EDC widely used in the production of polyvinyl chloride products and an ubiquitous environmental contaminant. We used a rat model system to show that fetal exposure to DEHP decreased levels of major steroid hormones in adulthood and that environmentally-relevant levels of DEHP affected both gene expression and epigenomic loci that were affected by exposure to high levels. In the adrenal gland, we reported that the peroxisome proliferator-activated receptor (PPAR) and cholesterol biosynthesis pathways were sensitive targets of DEHP. We hypothesized that low levels of DEHP exposure insult the endocrine system (a "first hit") and increase its susceptibility to later exposure ("second hit") and subsequent disease. Here, we demonstrate that a second hit in the adult offspring exposed in utero to low levels of DEHP affected serum aldosterone levels. To unveil the first hit influence of early DEHP exposure, we treated in utero DEHP-exposed adult offspring with stressors that targeted the PPAR or cholesterol biosynthesis pathways. Treatment with the PPAR-gamma antagonist T0070907 reduced serum aldosterone compared to animals not exposed to DEHP in utero. Analysis of gene expression in animals that were subjected to both early and late exposure revealed deregulation of genes for the potassium channel Kcnk5 and the retinoid-X receptors (RXR) Rxra and Rxrb, indicating that these entities are linked to endocrine disruption. We propose that early exposure to environmental doses of DEHP predisposes the animal for disease later in life.