Ultimobranchial Research Articles

An ultimobranchial thyroid cyst in a horse

SummaryA one‐year‐old female trotter was examined for an enlarging mass on the proximoventral aspect on the right side of the proximal cervical area. On clinical and ultrasonographic examination the mass was found to be a fluid filled cavity of approximately 8 cm in diameter surrounded by a capsule. The right lobe of the thyroid gland was closely related to the mass. The mass and the right thyroid gland were surgically excised. Histological examination revealed an ultimobranchial cyst. This is the first description of the diagnosis and treatment of a thyroid cystic abnormality related to the fifth branchial pouch (ultimobranchial body) in a horse.

Thyroid ultrasound findings in children from three Japanese prefectures: Aomori, Yamanashi and Nagasaki.

Due to the likelihood of physical and mental health impacts following the unprecedented accident at the Fukushima Dai-ichi Nuclear Power Plant, the Fukushima prefectural government decided to conduct the Fukushima Health Management Survey to assist in the long-term health management of residents. This included thyroid ultrasound examination for all children in Fukushima. For appropriate evaluation of ultrasound screening of the thyroid, it is important to understand its reference data of thyroid findings in children in general. In order to analyze the frequencies of specific thyroid findings, we conducted ultrasound screening of the thyroid by the same procedures as used in Fukushima in 4,365 children, aged 3 to 18 years, from three Japanese prefectures. Overall, thyroid cysts were identified in 56.88% and thyroid nodules in 1.65% of the participants. Thyroid cysts and nodules with a maximum diameter of more than 5 mm were identified in 4.58% and 1.01%, respectively, and age-adjusted prevalences were 3.82% and 0.99%, respectively. Although the prevalence of cysts and nodules varied among the examination areas, no significant differences were observed among the three examination areas in the prevalence of cysts and nodules with a maximum diameter of more than 5 mm. Also, the prevalence of thyroid cysts and nodules, especially those with a maximum diameter of more than 5 mm, significantly increased with age, and showed a female predominance. We also identified ectopic thymus (1.95%), diffuse goiter (1.40%), ultimobranchial body (0.73%), lymph node swelling (0.21%) and thyroid agenesis (0.05%). This is the first ultrasound description of the age-adjusted prevalence of thyroid cysts and nodules, or of the prevalence of abnormalities other than cysts and nodules, such as ectopic thymus, in relation to age, in the general Japanese child population. We contend that this can provide relevant information for the Fukushima Health Management Survey and future population studies.

Influence of a botanical pesticide, azadirachtin, on ultimobranchial gland of the freshwater catfish Heteropneustes fossilis

Freshwater catfish, Heteropneustes fossilis, were subjected to 42 mg L−1 of azadirachtin for short-term exposure (96 h) and to 10.5 mg L−1 for long-term exposure (28 days). Six fishes were sacrificed on each time interval from control and experimental groups after 24, 48, 72, and 96 h in the short-term exposure and after 7, 14, 21, and 28 days in the long-term experiment. The calcium regulating endocrine gland, viz. the ultimobranchial gland, was fixed for histological studies. Up to 72 h of azadirachtin treatment, there was no histological alteration in the UBG (ultimobranchial gland) of H. fossilis. After 96 h exposure, the ultimobranchial cells stain feebly and the nuclear volume of these cells were slightly decreased. No histological alterations have been observed in the UBG cells up to 14 days following azadirachtin exposure. After 21 days, the cytoplasm of ultimobranchial cells was feebly stained and the nuclear volume exhibits a decrease. The nuclear volume of these cells was further decreased and the gland shows vacuolization and degeneration at certain places after 28 days azadirachtin treatment. Hence, it can be concluded that azadirachtin severely affects the physiology of calcium homeostasis in H. fossilis. Therefore, the botanical pesticides should be used carefully near aquatic reservoirs.

Histomorphological study of the parathyroid gland in female Kuttanad ducks (Anas platyrhynchos domesticus)

Aim: Materials and Methods: A Histomorphological study of the parathyroid gland was carried out in twelve adult female Kuttanad ducks (Anas platyrhynchos domesticus) of 20 weeks of age. Birds reared semintensively were procured from Kerala Veterinary and Animal Sciences University Poultry and Duck Farm and sacrificed humanely. Glands were collected and gross parameters were recorded. The glands were fixed in 10 percent neutral buffered formalin. The small sized glands were processed as such by routine histological methods, paraffin blocks were prepared and sectioned to a thickness of 5µ. The tissues were stained by Haematoxylin and Eosin (H&E) for routine histological studies and Gomori's rapid one step trichrome method for connective tissue fibres. Micrometric parameters were recorded using ocular micrometer. Results: Parathyroid glands in Kuttanad ducks lay just caudal to the division of the innominate artery into the subclavian and common carotid arteries. Parathyroids were oval to spherical in shape, yellow in colour and smaller than thyroid gland of the representative sides. The arterial blood supply was from common carotid artery and blood from gland was drained directly into jugular vein. Although it lied close to the thyroid, thymus and ultimobranchial gland, parathyroid tissue did not merge to any of the above mentioned three glands. Parenchyma was composed irregular anatomizing cords of cells supplied by connective tissue stroma penetrated by blood capillaries. Parenchyma was predominantly made of lightly stained cell, the chief cell. The nuclei were round and contain one or two nucleoli. Oxyphil cells present in parathyroid glands of other mammals were not seen in the present study. Conclusion: Histomorphological features or characteristics of Parathyroid gland in Kuttanad duck were studied. Cranial parathyroids were larger in size as compared to the caudal parathyroids. Parathyroid glands were enclosed by a welldeveloped connective tissue capsule made predominantly of collagen fibers. Parenchyma was composed of irregular anatomizing cords of cells supplied by connective tissue stroma and penetrated by blood capillaries. Oxyphil cells were absent similar to other aves. Parathyroid gland is very vital in maintaining the homeostasis of the plasma calciumReference?. Findings of this study will contribute to the anatomy literature as a valuable resource for future researchers focused on this subject and will also help other allied subjects on comparative basis.

Hypocalcemic Role Of Calcitonin In Female Mastacembelus Armatus (lacepede), During Reproductive Cycle

On the basis of various histological changes the ovarian cycle of Mastacembelus armatus can be divided in to five different phases i.e. resting, maturation, prespawning, spawning and postspawning phases. Seasonal cyclic changes in the plasma calcium and calcitonin level were found associated with this ovarian cycle. An increase in their level occurs during maturation phase with a corresponding increase in the gonadosomatic index reaching the peak during prespawning phase and spawning phase. On the other hand a significant decrease was noted during postspawning and resting phase. Histological changes in the ultimobranchial gland also revealed the seasonal variation in its activity. It exhibits various signs of hyperactivity like Maximum increase in the population of secretory cells, decrease in size of lumen and dilation of blood vessels during prespawning and spawning phase. Disruptive follicular organization was noted during resting and post spawning phase. 17-â estradiol administration resulted in hypercalcemia and increase in plasma calcitonin level in M. armatus fed with calcium deficient food. Therefore it can be concluded that UBG is mainly concerned with reproductive physiology of the fish M. Armatus by lowering down elevated plasma calcium level accompanied through extra intestinal routes during ovarian maturation.

Hes1 is required for the development of pharyngeal organs and survival of neural crest-derived mesenchymal cells in pharyngeal arches

Hes genes are required to maintain diverse progenitor cell populations during embryonic development. Loss of Hes1 results in a spectrum of malformations of pharyngeal endoderm-derived organs, including the ultimobranchial body (progenitor of C cells), parathyroid, thymus and thyroid glands, together with highly penetrant C-cell aplasia (81%) and parathyroid aplasia (28%). The hypoplastic parathyroid and thymus are mostly located around the pharyngeal cavity, even at embryonic day (E) 15.5 to E18.5, indicating the failure of migration of the organs. To clarify the relationship between these phenotypes and neural crest cells, we examine fate mapping of neural crest cells colonized in pharyngeal arches in Hes1 null mutants by using the Wnt1-Cre/R26R reporter system. In null mutants, the number of neural crest cells labeled by X-gal staining is markedly decreased in the pharyngeal mesenchyme at E12.5 when the primordia of the thymus, parathyroid and ultimobranchial body migrate toward their destinations. Furthermore, phospho-Histone-H3-positive proliferating cells are reduced in number in the pharyngeal mesenchyme at this stage. Our data indicate that the development of pharyngeal organs and survival of neural-crest-derived mesenchyme in pharyngeal arches are critically dependent on Hes1. We propose that the defective survival of neural-crest-derived mesenchymal cells in pharyngeal arches directly or indirectly leads to deficiencies of pharyngeal organs.

INFLUENCE OF PROLACTIN ON THE ULTIMOBRANCHIAL BODIES OF BUFO VIRIDIS

ABSTRACT Prolactin effects on the behaviour and on the ultimobranchial body (UBB) of the toad Bufo viridis were investigated since prolactin (or a similar substance) occurs in the adenohypophysis of certain amphibians and induces a water-drive in certain salamanders, and because previous investigations point to the probable dependence of B. viridis' UBB on its ecological conditions. Toads (N=33; size, 26–60 mm; controls, N= 30) were injected with prolactin (courtesy U.S. National Inst, of Health). Whereas controls remained quiet, injected toads were active, restless, and appeared to strive to escape. This behaviour is attributed to the initiation of a water-drive. Histological examination revealed drastic changes in the UBB of injected toads, culminating in the formation of enormous cysts which contain undifferentiated clotted material. These are interpreted as a sign of extreme exhaustion of the UBB following its over-stimulation. These results suggest that the UBB is influenced by prolactin and is invol...

Postnatal fate of the ultimobranchial remnants in the rat thyroid gland

The ultimobranchial follicles (UBFs) are considered embryonic remnants from the ultimobranchial body (UBB). They are follicular structures that vary in size and appearance depending on the age of the rat. The main objective of this article was to study the progressive changes in shape, size, and frequency of the UBFs in the postnatal rat, from birth to old-age. To accomplish that objective, a systematic morphometric and incidental study of the UBF has been carried out in 110 Wistar rats of different ages and both sexes, divided into three groups: 1) young rats (5-90-day-old); 2) adult rats (6-15-month-old), and 3) old rats (18-24-month-old). The glands were serially sectioned and immunostained for calcitonin at five equidistant levels. According to our results, UBFs were observed in all thyroid glands but a more exhaustive sampling was occasionally necessary in male rats. In young rats, immature UBFs predominantly appeared whereas in adult rats, mature UBFs with cystic appearance and variable luminal content prevailed. We frequently found spontaneous anomalous UBFs in old rats, which we have termed as "ultimobranchial cystadenomata." Additionally, in young rats, UBF areas significantly increased with age and they were larger when compared to that of normal thyroid follicles. Likewise, in adult rats, UBFs were significantly larger than normal thyroid follicles but only in female rats. In general, UBFs in females were also significantly larger than those found in male rats. Finally, all these differences related to UBFs together with a higher incidence in females of UB cystadenomata suggest a sexual dimorphism in regard to the destiny of these embryonic remnants during postnatal thyroid development.

Misguided Migration of C Cell Precursors to Extra-Thyroidal Locations Related to Defective Pharyngeal Pouch Development in Shh Deficient Mice

A possible role of sonic hedgehog (Shh) in recruitment of C cell precursors to the Ultimobranchial Body (UB) and embryonic thyroid was investigated in Shh-/- mice. Nkx2.1 and Foxa2 co-expression distinguished UB originating in the fourth pharyngeal pouch from other derivatives of pharyngeal endoderm. In mutants UB formed a single structure that failed to bud and instead of fusing with the midline thyroid primordium adhered to the thymic rudiments. Mature C cells appeared in the UB remnant and ectopically in the thymic parenchyma, foregut endoderm and trachea. Thyroid did not contain C cells except minute numbers close to the tracheal interface. Tracing progeny in Shh-CRE/Rosa26R mice showed the vast majority of both UB and thyroid progenitors derived from Shh negative endoderm, but Shh expressing cells appeared in both thyroid primordia before fusion of the two. The findings indicate that Shh determines the endoderm territory for C cell differentiation and guides the migration of C cell precursors into the thyroid, presumably by regulating the separation of glandular domains in the pharyngeal pouch endoderm. A cell-autonomous role of Shh in thyroid morphogenesis is suggested.

Ultrastructural Studies on the Ultimobranchial Bodies of Freshwater Turtle Lissemys punctata Granulosa

In the background that there is scanty literature on the ultrastructure of ultimobranchial bodies of the fresh-water turtles, this paper describes the ultrastructure of the gland of freshwater turtle Lissemys punctata granulosa . The gland was dissected out and subjected to transmission electron microscopic analysis to examine the structure of the gland. The gland is composed of a single type of cells with a few secretory granules of similar size, large cytoplasmic bodies, Golgi region, and fewer mitochondria.

Follicular Variant of Papillary Carcinoma Arising From Lingual Thyroid With Orthotopic Hypoplasia of Thyroid Lobes

The human thyroid gland derives from a median anlage and 2 lateral anlagen. The development of the thyroid occurs during weeks 3 to 7 of embryologic development when the median anlage descends from the foramen cecum to its usual pretracheal location. Toward the end of the migration, the lateral anlagen dissociate from the caudal base of the fourth and fifth pharyngeal pouches to migrate medially and join the thyroid gland. This structure is called the ultimobranchial body, and it contributes the parafollicular cells (or C cells) and 1% to 30% of the thyroid weight. Failure of median anlage descent can result in ectopic deposition of thyroid tissue anywhere along the path of descent. The most common location for ectopia of the thyroid is the tongue base, known as lingual

Documented and potential research impacts of subclinical diseases in zebrafish.

The zebrafish (Danio rerio) has become a very important animal model in biomedical research. In contrast with other models, such as mice, there has been relatively little documentation or control of subclinical disease in zebrafish research facilities. Several infectious and noninfectious conditions are consistently detected by histopathology in apparently healthy D. rerio. The most commonly observed infectious agent in zebrafish is Pseudoloma neurophilia, which is a microsporidian organism that targets the central nervous system, peripheral nerves, and occasionally other tissues. Mycobacteriosis, caused by Mycobacterium chelonae and other species, is also a frequent finding. Less commonly encountered agents include Pseudocapillaria tomentosa, which can cause extensive proliferative enteritis, and a myxozoan (Myxidium sp.) that inhabits the urinary tract but appears to cause few if any pathological changes. Noninfectious diseases that are often clinically unapparent in zebrafish include hepatic megalocytosis, bile and pancreatic ductal proliferation, and neoplasms of the ultimobranchial gland, gastrointestinal tract, and testis. To date, there is little information on the degree to which these conditions may impact research in subclinically affected fish, but there is reason to believe that they should be considered as potentially significant causes of nonprotocol variation in experiments. Therefore, it is imperative that research facilities monitor their stocks for the presence of these occult diseases and be aware of their existence when interpreting study results. Furthermore, for underlying disease conditions that cannot be readily eradicated, it is essential to determine the physiological and immunological changes that they elicit in zebrafish. Understanding the cause, modes of transmission, and distribution of the pathogens would provide useful information for the development of control and prevention strategies.

Ultimobranchial Body Remnants (Solid Cell Nests) as a Pitfall in Thyroid Pathology

We report the history of a pitfall in thyroid histopathology of a 47-yr-old man with a euthyroid nodular goiter involving the right lobe. The ultrasound-guided fineneedle aspiration of the dominant (3 cm) nodule, showing benign-appearing follicular cells, colloid, and scattered Hurthle cells, was consistent with a benign hyperplastic nodule (1). Because the left lobe had not shown evidence of nodular disease, the patient was submitted to a right lobectomy. The pathologist described a heavy lymphoplasmacyticbackgroundwithoccasionalgerminalcenter formation, as observed in Hashimoto thyroiditis, and a microscopic ( 1cm) follicularproliferationofepithelial thyroidcellswhose nucleidisplayedmembrane irregularityandchromatinclearing with occasional grooves. Thus, a histological report of a follicular variant of papillary microcarcinoma was issued. The patient underwent a completion thyroidectomy at the Federico II UniversityofNaples.At thatoccasion, thecompletesetofslides from both surgeries was reviewed by expert pathologists in the field of thyroid disease.

Evidence for Calcitonin-Producing Cells in Human Lingual Thyroids

The thyroid contains two types of cells, the thyroid follicular cells and the calcitonin-producing cells. The site of origin of the thyroid follicular cells is the median thyroid anlage, an endothelial diverticulum in the midline of the ventral pharynx between the first and the second pharyngeal pouches. The ultimobranchial bodies (UBB), a pair of transient embryonic structures evaginated from the fourth pharyngeal pouch and located symmetrically on the sides of the developing neck, are the source of calcitonin-producing cells. In human embryos, the thyroid bud starts its migration at embryonic day 24 and reaches its final location in front of the trachea at embryonic day 45-50. The UBB fuse with the primitive thyroid when thyroid migration is completed. Lingual thyroids result from the failure of the thyroid precursor cells to migrate from the primordial pharynx to the anterior part of the neck. Therefore, calcitonin-producing cells are not expected to be present in lingual thyroids. Our objective was to determine whether calcitonin-producing C cells are present in ectopic lingual thyroids. We performed calcitonin immunolabeling and transcript detection on four flash-frozen ectopic lingual thyroids. Additional calcitonin immunolabeling was performed on two other paraffin-embedded ectopic lingual thyroids. We report evidence of calcitonin-producing cells in six independent cases of ectopic lingual thyroids. The UBB are not the only source of calcitonin-producing cells in humans. Interactions between calcitonin-producing and thyroid follicular cells occur earlier than previously accepted.

<i>Euphorbia royleana</i>, a botanical pesticide affects ultimobranchial gland of the catfish <i>Heteropneustes fossilis</i>

Heteropneustes fossilis were subjected to high and low doses of the latex of Euphorbia royleana for short-term and long-term exposures, respectively. The blood was analyzed for plasma calcium levels, and the ultimobranchial glands fixed and examined. Serum calcium levels declined after 48 h following short-term exposure, and this decrease continued until the end of the experiment. The ultimobranchial cells exhibited a decrease in the cytoplasmic staining response after 96 h following treatment, and the nuclear volumes slightly decreased. Chronically exposed fish also exhibited a decline in serum calcium levels, but much later, on day 7, again progressively declining until the close of the experiment. Up to day 14 following treatment there was no change in histological structure of the ultimobranchial glands, but then there was a decrease in nuclear volume and the cytoplasm displayed a weak staining response. There was some vacuolization and degeneration. Keywords: Botanicals, calcitonin, calcium, teleost

Nerium indicum, a botanical pesticide affects ultimobranchial gland of the catfish Heteropneustes fossilis

Heteropneustes fossilis were subjected to 11.27 mg L(-1) (80% of 96 h LC50 ) and 2.81 mg L(-1) (20% of 96 h LC50 ) of Nerium indicum leaf extract for short-term and long-term, respectively. After sacrificing the fish, blood was collected on 24, 48, 72, and 96 h in short-term and after 7, 14, 21, and 28 days in long-term experiment and analyzed for plasma calcium levels. Also, ultimobranchial glands (UBG) were fixed on these intervals. Serum calcium levels of H. fossilis exhibited a decline after 48 h following exposure to Nerium indicum leaf extract. This decrease continued till the end of the experiment (96 h). Ultimobranchial cells exhibited a decrease in the cytoplasmic staining response after 72 h following the treatment. The nuclear volumes of these cells were slightly decreased. These changes were exaggerated after 96 h following the treatment. Chronically exposed fish exhibited a decline in serum calcium levels of H. fossilis on day 14. The level progressively declined till the end of the experiment. Up to day 14 following the treatment there was no change in the histological structure of UBG. A decrease in the nuclear volume of ultimobranchial cells was noticed on day 21. Moreover, the cytoplasm of these cells displayed weakstaining response. The nuclear volume of these cells recorded a further decrease following 28-day treatment. Also there was noticed vacuolization and degeneration at certain places. To the best of our knowledge, the effects of any botanical pesticides on fish UBG have not been reported yet.

Histological alterations in the ultimobranchial gland of teleost Heteropneustes fossilis in response to chlorpyrifos treatment

In this study, an experiment was performed on Heteropneustes fossilis for short-term (1.76 mg/L chlorpyrifos, i.e., 0.8 of 96-h LC50) and long-term (0.44 mg/L chlorpyrifos, i.e., 0.2 of 96-h LC50) exposure. The fish were sacrificed after 24, 48, 72 and 96 h in the short-term experiment and after 7, 14, 21 and 28 days in the long-term experiment. On these intervals, blood was collected and analysis of serum calcium was done. Ultimobranchial glands were also fixed for histological study. The serum calcium levels of H. fossilis exhibit a decline after 24 h following exposure to chlorpyrifos. This decrease continues until the end of the experiment (96 h). The serum calcium levels of chronically exposed fish exhibit a decrease on day 7. Thereafter, the levels continue to fall progressively until the end of the experiment (28 days). The ultimobranchial gland of chlorpyrifos treated fish exhibits no histological change up to 48 h. After 72 h, there is a decrease in the staining response of cytoplasm of the ultimobranchial cells. The nuclear volume of these cells is slightly decreased. After 96 h following chlorpyrifos exposure, these changes become exaggerated. In chlorpyrifos-treated fish there is no change in the histological structure of the ultimobranchial gland up to 14 days. After 21 days, the cytoplasm of ultimobranchial cells stain feebly and the nuclear volume of these cells exhibits a decrease. Following 28 days treatment, the nuclear volume of these cells records a further decrease and the gland depicts vacuolization and degeneration at certain areas.

Role of EphA4 Receptor Signaling in Thyroid Development: Regulation of Folliculogenesis and Propagation of the C-Cell Lineage

Transcriptome analysis revealed that the tyrosine kinase receptor EphA4 is enriched in the thyroid bud in mouse embryos. We used heterozygous EphA4-EGFP knock-in mice in which enhanced green fluorescent protein (EGFP) replaced the intracellular receptor domain (EphA4(+/EGFP)) to localize EphA4 protein in thyroid primordial tissues. This showed that thyroid progenitors originating in the pharyngeal floor express EphA4 at all embryonic stages and when follicles are formed in late development. Also, the ultimobranchial bodies developed from the pharyngeal pouch endoderm express EphA4, but the ultimobranchial epithelium loses the EGFP signal before it merges with the median thyroid primordium. Embryonic C cells invading the thyroid are exclusively EphA4-negative. EphA4 expression continues in the adult thyroid. EphA4 knock-out mice and EphA4-EGFP homozygous mutants are euthyroid and have a normal thyroid anatomy but display subtle histological alterations regarding number, size, and shape of follicles. Of particular interest, the pattern of follicular abnormality differs between EphA4(-/-) and EphA4(EGFP/EGFP) thyroids. In addition, the number of C cells is reduced by >50% exclusively in animals lacking EphA4 forward signaling (EphA4(EGFP/EGFP)). Heterozygous EphA4 mutants have no apparent thyroid phenotype. We conclude that EphA4 is a novel regulator of thyroid morphogenesis that impacts on postnatal development of the two endocrine cell lineages of the differentiating gland. In this process both EphA4 forward signaling (in the follicular epithelium) and reverse signaling mediated by its cognate ligand(s) (A- and/or B-ephrins expressed in follicular cells and C cells, respectively) are probably functionally important.

Hes1 Is Required for Appropriate Morphogenesis and Differentiation during Mouse Thyroid Gland Development

Notch signalling plays an important role in endocrine development, through its target gene Hes1. Hes1, a bHLH transcriptional repressor, influences progenitor cell proliferation and differentiation. Recently, Hes1 was shown to be expressed in the thyroid and regulate expression of the sodium iodide symporter (Nis). To investigate the role of Hes1 for thyroid development, we studied thyroid morphology and function in mice lacking Hes1. During normal mouse thyroid development, Hes1 was detected from E9.5 onwards in the median anlage, and at E11.5 in the ultimobranchial bodies. Hes1 −/− mouse embryos had a significantly lower number of Nkx2-1-positive progenitor cells (p<0.05) at E9.5 and at E11.5. Moreover, Hes1 −/− mouse embryos showed a significantly smaller total thyroid surface area (−40 to −60%) compared to wild type mice at all study time points (E9.5−E16.5). In both Hes1 −/− and wild type mouse embryos, most Nkx2-1-positive thyroid cells expressed the cell cycle inhibitor p57 at E9.5 in correlation with low proliferation index. In Hes1 −/− mouse embryos, fusion of the median anlage with the ultimobranchial bodies was delayed by 3 days (E16.5 vs. E13.5 in wild type mice). After fusion of thyroid anlages, hypoplastic Hes1 −/− thyroids revealed a significantly decreased labelling area for T4 (−78%) and calcitonin (−65%) normalized to Nkx2-1 positive cells. Decreased T4-synthesis might be due to reduced Nis labelling area (−69%). These findings suggest a dual role of Hes1 during thyroid development: first, control of the number of both thyrocyte and C-cell progenitors, via a p57-independent mechanism; second, adequate differentiation and endocrine function of thyrocytes and C-cells.

Inmunohistochemical Profile of Solid Cell Nest of Thyroid Gland

It is widely held that solid cell nests (SCN) of the thyroid are ultimobranchial body remnants. SCNs are composed of main cells and C cells. It has been suggested that main cells might be pluripotent cells contributing to the histogenesis of C cells and follicular cells, as well as to the formation of certain thyroid tumors. The present study sought to analyze the immunohistochemical profile of SCN and to investigate the potential stem cell role of SCN main cells. Tissue sections from ten cases of nodular hyperplasia (non-tumor goiter) with SCNs were retrieved from the files of the Hospital Infanta Luisa (Seville, Spain). Parathormone (PTH), calcitonin (CT), thyroglobulin (TG), thyroid transcription factor (TTF-1), galectin 3 (GAL3), cytokeratin 19 (CK 19), p63, bcl-2, OCT4, and SALL4 expression were evaluated by immunohistochemistry. Patient clinical data were collected, and tissue sections were stained with hematoxylin–eosin for histological examination. Most cells stained negative for PTH, CT, TG, and TTF-1. Some cells staining positive for TTF-1 and CT required discussion. However, bcl-2, p63, GAL3, and CK 19 protein expression was detected in main cells. OCT4 protein expression was detected in only two cases, and SALL4 expression in none. Positive staining for bcl-2 and p63, and negative staining for PTH, CT, and TG in SCN main cells are both consistent with the widely accepted minimalist definition of stem cells, thus supporting the hypothesis that they may play a stem cell role in the thyroid gland, although further research will be required into stem cell markers. Furthermore, p63 and GAL-3 staining provides a much more sensitive means of detecting SCNs than staining for carcinoembryonic antigen, calcitonin, or other markers; this may help to distinguish SCNs from their mimics.